This PDF file contains the front matter associated with SPIE Proceedings Volume 8442, including the Title Page, Copyright information, Table of Contents, Introduction, and Conference Committee listing.

The Cosmic Microwave Background (CMB) is a relict of the early universe. Its perfect 2.725K blackbody spectrum demonstrates that the universe underwent a hot, ionized early phase; its anisotropy (about 80 µK rms) provides strong evidence for the presence of photon-matter oscillations in the primeval plasma, shaping the initial phase of the formation of structures; its polarization state (about 3 µK rms), and in particular its rotational component (less than 0.1 µK rms) might allow to study the inflation process in the very early universe, and the physics of extremely high energies, impossible to reach with accelerators. The CMB is observed by means of microwave and mm-wave telescopes, and its measurements drove the development of ultra-sensitive bolometric detectors, sophisticated modulators, and advanced cryogenic and space technologies. Here we focus on the new frontiers of CMB research: the precision measurements of its linear polarization state, at large and intermediate angular scales, and the measurement of the inverse-Compton effect of CMB photons crossing clusters of Galaxies. In this framework, we will describe the formidable experimental challenges faced by ground-based, near-space and space experiments, using large arrays of detectors. We will show that sensitivity and mapping speed improvement obtained with these arrays must be accompanied by a corresponding reduction of systematic effects (especially for CMB polarimeters), and by improved knowledge of foreground emission, to fully exploit the huge scientific potential of these missions.

Small-angle coronagraphy is technically and scientifically appealing because it enables the use of smaller telescopes, allows covering wider wavelength ranges, and potentially increases the yield and completeness of circumstellar environment – exoplanets and disks – detection and characterization campaigns. However, opening up this new parameter space is challenging. Here we will review the four posts of high contrast imaging and their intricate interactions at very small angles (within the first 4 resolution elements from the star). The four posts are: choice of coronagraph, optimized wavefront control, observing strategy, and post-processing methods. After detailing each of the four foundations, we will present the lessons learned from the 10+ years of operations of zeroth and first-generation adaptive optics systems. We will then tentatively show how informative the current integration of second-generation adaptive optics system is, and which lessons can already be drawn from this fresh experience. Then, we will review the current state of the art, by presenting world record contrasts obtained in the framework of technological demonstrations for space-based exoplanet imaging and characterization mission concepts. Finally, we will conclude by emphasizing the importance of the cross-breeding between techniques developed for both ground-based and space-based projects, which is relevant for future high contrast imaging instruments and facilities in space or on the ground.

Photonic crystal, an artificial periodic nanostructure of refractive indices, is one of the attractive technologies for coronagraph focal-plane masks aiming at direct imaging and characterization of terrestrial extrasolar planets. We manufactured the eight-octant phase mask (8OPM) and the vector vortex coronagraph (VVC) mask very precisely using the photonic crystal technology. Fully achromatic phase-mask coronagraphs can be realized by applying appropriate polarization filters to the masks. We carried out laboratory experiments of the polarization-filtered 8OPM coronagraph using the High-Contrast Imaging Testbed (HCIT), a state-of-the-art coronagraph simulator at the Jet Propulsion Laboratory (JPL). We report the experimental results of 10^-8-level contrast across several wavelengths over 10% bandwidth around 800nm. In addition, we present future prospects and observational strategy for the photonic-crystal mask coronagraphs combined with differential imaging techniques to reach higher contrast. We proposed to apply the polarization-differential imaging (PDI) technique to the VVC, in which we built a two-channel coronagraph using polarizing beam splitters to avoid a loss of intensity due to the polarization filters. We also proposed to apply the angular-differential imaging (ADI) technique to the 8OPM coronagraph. The 8OPM/ADI mode mitigates an intensity loss due to a phase transition of the mask and provides a full field of view around central stars. We present results of preliminary laboratory demonstrations of the PDI and ADI observational modes with the phase-mask coronagraphs.

EChO is an M-class mission candidate within the science program Cosmic Vision 2015-2025 of the European Space Agency. It was selected in February 2011 to enter an assessment phase (phase 0/A). Following the internal Concurrent Design Facility study conducted by ESA in June/July 2011, a call for instrument studies was released in September, resulting in two consortia being selected to study the complete science instrument on board EChO throughout 2012. Similarly, two parallel competitive industrial studies of the complete mission will end early 2013. The instrument study focuses on the design and accommodation in the spacecraft of the scientific instrument, a spectrometer divided into several channels covering the 0.55 to 11 micron (0.4 to 16 micron goal) wave band. It also includes the design of the active cryogenic chain required to operate the instrument focal plane detectors. The industrial study focuses on the complete system-level design, including the mission analysis and operations, the spacecraft design (both service and payload modules) and also programmatic aspects such as risk mitigation, schedule and cost analyses. This paper describes the status of the EChO assessment study at the mid-term review (June/July 2012). It includes a short introduction to the EChO mission, a brief update on recent work by the Science Study Team (SST) to refine the science requirements, the description of the telescope trade-off and baseline selection, as well as the status of both instrument consortia and industrial system-level studies.

Context. To characterize their atmospheres in order to find evidences of life, one has to detect directly photons from the exoplanets to measure their spectra. One possible technique is dark fringe interferometry that needs an achromatic π phase shift in one arm of the interferometer. We have conceived a phase shifter made of two cellular mirrors, in which each cell position and phase shift is specific, so that the behaviour of the nulling with respect to wavelength is flat within a broad range. Aims. We want to validate experimentally two versions of this achromatic phase shifter: a transmissive one in bulk optics and a reflective one using a segmented deformable mirror. What we present in this paper are the last results obtained in the lab. Methods. We built an optical bench in the visible that allows us to test the principle and characterize the performances and the limits of this phase shifter. Results. We tested several transmissive and one reflective phase shifter and obtained, for instance, an attenuation of about 2.10^-3 for a white source (from 430 to 830 nm) that proved the achromatic behavior of the phase shifter. The preliminary performances and limitations are analyzed.

Herein we report on our Visible Nulling Coronagraph high-contrast result of 10⁹ contrast averaged over a focal plane region extending from 1 – 4 λ/D with the Vacuum Nuller Testbed (VNT) in a vibration isolated vacuum chamber. The VNC is a hybrid interferometric/coronagraphic approach for exoplanet science. It operates with high Lyot stop efficiency for filled, segmented and sparse or diluted-aperture telescopes, thereby spanning the range of potential future NASA flight telescopes. NASA/Goddard Space Flight Center (GSFC) has a well-established effort to develop the VNC and its technologies, and has developed an incremental sequence of VNC testbeds to advance this approach and its enabling technologies. These testbeds have enabled advancement of high-contrast, visible light, nulling interferometry to unprecedented levels. The VNC is based on a modified Mach-Zehnder nulling interferometer, with a “W” configuration to accommodate a hex-packed MEMS based deformable mirror, a coherent fiber bundle and achromatic phase shifters. We give an overview of the VNT and discuss the high-contrast laboratory results, the optical configuration, critical technologies and null sensing and control.

Coronagraph technology is advancing and promises to enable space telescopes capable of seeing debris disks as well as seeing and spectrally characterizing exo-Earths. Recently, NASA's explorer program has selected the EXCEDE (EXoplanetary Circumstellar Environments and Disk Explorer) mission concept for technology development. EXCEDE is a 0.7m space telescope concept designed to achieve raw contrasts of 1e-6 at an inner working angle of 1.2 λ/D and 1e- 7 at 2 λ/D. In addition to doing fundamental science on debris disks, EXCEDE will also serve as a technological and scientific precursor for an exo-Earth imaging mission. EXCEDE uses a Starlight Suppression System (SSS) based on the Phase Induced Amplitude Apodization (PIAA) coronagraph to provide high throughput and high contrast close to the diffraction limit, enabling aggressive performance on small telescopes. We report on the latest progress in developing the SSS and present coronagraphic performance results from our air testbed at NASA Ames. Our results include a lab demonstration of 1e-5 contrast at 1.2 λ/D, 1.3e-6 contrast at 1.4 λ/D and 2e-8 at 2 λ/D in monochromatic light. In addition, we discuss tip-tilt instabilities, which are believed to be our main limiting factor at present, and ways of characterizing them.

It is likely that the coming decade will see the development of a large visible light telescope with enabling technology for imaging exosolar Earthlike planets in the habitable zone of nearby stars. One such technology utilizes an external occulter, a satellite flying far from the telescope and employing a large screen, or starshade, to suppress the incoming starlight suffciently for detecting and characterizing exoplanets. This trades the added complexity of building the precisely shaped starshade and flying it in formation against simplifications in the telescope since extremely precise wavefront control is no longer necessary. In this paper we present the results of our project to design, manufacture, and measure a prototype occulter petal as part of NASA's first Technology Development for Exoplanet Missions program. We describe the mechanical design of the starshade and petal, the precision manufacturing tolerances, and the metrology approach. We demonstrate that the prototype petal meets the requirements and is consistent with a full-size occulter achieving better than 10^-10 contrast.

In a setup similar to the self coherent camera, we have added a set of pinholes in the diffraction ring of the Lyot plane in a high-contrast stellar Lyot coronagraph. We describe a novel complex electric field reconstruction from image plane intensity measurements consisting of light in the coronagraph's dark hole interfering with light from the pinholes. The image plane field is modified by letting light through one pinhole at a time. In addition to estimation of the field at the science camera, this method allows for self-calibration of the probes by letting light through the pinholes in various permutations while blocking the main Lyot opening. We present results of estimation and calibration from the High Contrast Imaging Testbed along with a comparison to the pair-wise deformable mirror diversity based estimation technique. Tests are carried out in narrow-band light and over a composite 10% bandpass.

The Stroke Minimization algorithm developed at the Princeton High Contrast Imaging Laboratory has proven symmetric dark hole generation using minimal stroke on two deformable mirrors (DM) in series. The windowed approach to Stroke Minimization has proven symmetric dark holes over small bandwidths by using three wavelengths to define the bandwidth of correction in the optimization problem. We address the relationship of amplitude and phase aberrations with wavelength, how this changes with multiple DMs, and the implications for simultaneously correcting both to achieve symmetric dark holes. Operating Stroke Minimization in the windowed configuration requires multiple wavelength estimates. To save on exposures, a single estimate is extrapolated to bounding wavelengths using the established relationship in wavelength to produce multiple estimates of the image plane electric field. Here we demonstrate better performance by improving this extrapolation of the estimate to other wavelengths. The accuracy of the functional relationship will ultimately bound the achievable bandwidth, therefore as a metric these results are also compared to estimating each wavelength separately. In addition to these algorithm improvements, we also discuss a laboratory upgrade and how it can better simulate broadband starlight. We also discuss the possibility of leveraging two DMs in series to directly estimate the electric field over a narrow bandwidth and the challenges associated with it.

We present the initial test of the dark-hole correction for the high-contrast imaging coronagraph that is based on the step-transmission filter. The dark hole is created by a 12x12 actuator deformable mirror (DM) that has been put in the conjugate plane of the pupil image of the coronagraph. In this test, we use the stochastic parallel gradient descent (SPGD) optimization algorithm to directly control the DM to provide an optimal phase to minimize the intensity in target regions, where the dark hole is created and the contrast can be enhanced. For demonstration purpose, the test is carried out in a single wavelength and should be improved in next step for broad-band high-contrast imaging. Finally, it is shown in the test that an extra contrast ~50 times improvement has reached in the dark hole in the coronagraphic image plane. Such a technique could be used for a future space-based high-contrast observation and is promising for the direct imaging of an Earth-like exoplanet.

The Planetary Imaging Concept Testbed Using a Rocket Experiment (PICTURE 36.225 UG) was designed to directly image the exozodiacal dust disk of ǫ Eridani (K2V, 3.22 pc) down to an inner radius of 1.5 AU. PICTURE carried four key enabling technologies on board a NASA sounding rocket at 4:25 MDT on October 8th, 2011: a 0.5 m light-weight primary mirror (4.5 kg), a visible nulling coronagraph (VNC) (600-750 nm), a 32x32 element MEMS deformable mirror and a milliarcsecond-class fine pointing system. Unfortunately, due to a telemetry failure, the PICTURE mission did not achieve scientific success. Nonetheless, this flight validated the flight-worthiness of the lightweight primary and the VNC. The fine pointing system, a key requirement for future planet-imaging missions, demonstrated 5.1 mas RMS in-flight pointing stability. We describe the experiment, its subsystems and flight results. We outline the challenges we faced in developing this complex payload and our technical approaches.

We present the current status of the development of the SPICA Coronagraph Instrument (SCI). SPICA is a next-generation 3-meter class infrared telescope, which will be launched in 2022. SCI is high-contrast imaging, spectroscopic instrument mainly for direct detection and spectroscopy of extra-solar planets in the near-to-mid infrared wavelengths to characterize their atmospheres, physical parameters and evolutionary scenarios. SCI is now under the international review process. In this paper, we present a science case of SCI. The main targets of SCI, not only for direct imaging but also for spectroscopy, are young to matured giant planets. We will also show that some of known exoplanets by ground-based direct detection are good targets for SCI, and a number of direct detection planets that are suitable for SCI will be significantly increased in the next decade. Second, a general design of SCI and a key technology including a new high-throughput binary mask coronagraph, will be presented. Furthermore, we will show that SCI is potentially capable of achieving 10^-6 contrast by a PSF subtraction method, even with a telescope pointing error. This contrast enhancement will be important to characterize low-mass and cool planets.

Debris disks around nearby stars are tracers of the planet formation process, and they are a key element of our understanding of the formation and evolution of extrasolar planetary systems. With multi-color images of a significant number of disks, we can probe important questions: can we learn about planetary system evolution; what materials are the disks made of; and can they reveal the presence of planets? Most disks are known to exist only through their infrared flux excesses as measured by the Spitzer Space Telescope, and through images measured by Herschel. The brightest, most extended disks have been imaged with HST, and a few, such as Fomalhaut, can be observed using ground-based telescopes. But the number of good images is still very small, and there are none of disks with densities as low as the disk associated with the asteroid belt and Edgeworth­ Kuiper belt in our own Solar System. Direct imaging of disks is a major observational challenge, demanding high angular resolution and extremely high dynamic range close to the parent star. The ultimate experiment requires a space-based platform, but demonstrating much of the needed technology, mitigating the technical risks of a space-based coronagraph, and performing valuable measurements of circumstellar debris disks, can be done from a high-altitude balloon platform. In this paper we present a balloon-borne telescope concept based on the Zodiac II design that could undertake compelling studies of a sample of debris disks.

Direct detection and imaging of Exo-Earths is a prime candidate for the next Astrophysics flagship mission. Much effort is focused on developing the mission concept and technology to enable the direct imaging of an Exo-Earth. However, several key astronomical unknowns stand in the way of a fully optimized Exo-Earth imaging mission, the primary of which is the uncertainty in the Exo-Zodi brightness. By analogy to our own Zodiacal dust, Exo-Zodiacal dust is predicted to exist in the habitable zones of other stars, exactly in the locations where Exo-Earths would reside. Reflected light from this dust could be a primary background contribution to measurements of the Exo-Earth. We propose a mission concept called the Exo-Zodi Mapper (EZM) to obtain definitive measurements of the brightness of the Exo-Zodi dust around target stars which are the prime targets for a future mission aimed at the direct detection of Exo-Earths. Our mission concept uses a medium sized starshade that works with the James Webb Space Telescope to image and characterize the brightness and distribution of Exo-Zodiacal dust around ~40 primary target stars. This measurement would provide more precise requirements for the eventual Exo-Earth flagship mission, which may translate into significant savings. In addition, EZM can provide a host of ancillary science information on these important targets, including detailed maps of their dust distribution, studies of outer, giant planets, and exploration of the overall architecture of these planetary systems. The EZM starshade can also be used to enable high-contrast imaging of other targets of value to the astronomical community such as debris disks around young stars. We present an overview of the science that motivated the mission concept, the driving requirements, and the top level mission architecture.

The study of the physico-chemical properties of wide-separated exoplanets (> 1 AU) is a major goal of high-contrast imaging techniques. SPICES (Spectro-Polarimetric Imaging and Characterization of Exoplanetary Systems) is a project of space coronagraph dedicated to the spectro-polarimetric analysis of gas and ice giant planets, super-Earths and circumstellar disks in visible light at a spectral resolution of about 40. After recalling the science cases of the mission, we describe the optical design and the critical subsystems of the instrument. We then discuss the SPICES performance that we derived from numerical simulations.

The NEAT (Nearby Earth Astrometric Telescope) mission is a proposal submitted to ESA for its 2010 call for M-size mission within the Cosmic Vision 2015-2025 plan. The main scientific goal of the NEAT mission is to detect and characterize planetary systems in an exhaustive way down to 1 Earth mass in the habitable zone and further away, around nearby stars for F, G, and K spectral types. This survey would provide the actual planetary masses, the full characterization of the orbits including their inclination, for all the components of the planetary system down to that mass limit. NEAT will continue the work performed by Hipparcos and Gaia by reaching a precision that is improved by two orders of magnitude on pointed targets.

With sub-microarcsecond astrometry, exoplanets can be identified and their masses measured. Coronagraphic imaging of these exoplanets is required to study their atmospheres and surfaces in sufficient detail to identify possible signs of biological activity. We show how both measurements can be simultaneously acquired with a single telescope in which the central field is directed to a coronagraph instrument providing high contrast images, while the surrounding field is imaged with a wide field camera in which numerous faint background stars are used as an astrometric reference. To calibrate astrometric distortions due to optics and focal plane detector array imperfections and variations, we propose to place small dark spots on the telescope primary mirror. The spots, arranged in a regular grid containing no low spatial frequencies, do not affect the coronagraph performance. In the wide field image, they create diffraction spikes originating from the central bright star, which are affected by changes in intrumental distortions in exactly the same way as the background stars used for reference, thus allowing calibration of instrumental errors to micro-arcsecond level. We show that combining simultaneous astrometric and coronagraphic measurements allows reliable detection and characterization of exoplanets. Recent laboratory tests performed at the University of Arizona and NASA Ames validate the concept, demonstrating both the ability to accurately calibrate astrometric distortions, and compatibility with high contrast imaging systems.

The inner solar system, where the terrestrial planets formed and evolve, is populated by small grains of dust produced by collisions of asteroids and outgassing comets. At visible and infrared wavelengths, this dust cloud is in fact the most luminous component in the solar system after the Sun itself and the Earth may appear similar to a clump of zodiacal dust to an external observer. Hence, the presence of large amounts of dust in the habitable zone around nearby main-sequence stars is considered as a major hurdle toward the direct imaging of exoEarths with future dedicated space-based telescopes. In that context, we address in this paper the detectability of exoEarths embedded in structured debris disks with future space-based visible coronagraphs and mid-infrared interferometers. Using a collisional grooming algorithm, we produce models of dust clouds that simultaneously and self-consistently handle dust grain dynamics, including resonant interactions with planets, and grain-grain collisions. Considering various viewing geometries, we also derive limiting dust densities that can be tolerated around nearby main-sequence stars in order to ensure the characterization of exoEarths with future direct imaging missions.

We present the overview and the current status of SPICA (Space Infrared Telescope for Cosmology and Astrophysics), which is a mission optimized for mid- and far-infrared astronomy with a cryogenically cooled 3.2 m telescope. SPICA has high spatial resolution and unprecedented sensitivity in the mid- and far-infrared, which will enable us to address a number of key problems in present-day astronomy, ranging from the star-formation history of the universe to the formation of planets. To reduce the mass of the whole mission, SPICA will be launched at ambient temperature and cooled down on orbit by mechanical coolers on board with an efficient radiative cooling system, a combination of which allows us to have a 3-m class cooled (6 K) telescope in space with moderate total weight (3.7t). SPICA is proposed as a Japanese-led mission together with extensive international collaboration. ESA's contribution to SPICA has been studied under the framework of the ESA Cosmic Vision. The consortium led by SRON is in charge of a key focal plane instrument SAFARI (SPICA Far-Infrared Instrument). Korea and Taiwan are also important partners for SPICA. US participation to SPICA is under discussion. The SPICA project is now in the "risk mitigation phase". The target launch year of SPICA is 2022.

We are developing the Background-Limited Infrared-Submillimeter Spectrograph (BLISS) for SPICA to provide a breakthrough capability for far-IR survey spectroscopy. The 3.2-meter, actively-cooled (T<6K) SPICA telescope allows mid-IR to submm observations which are limited only by the natural backgrounds, and BLISS is designed to operate near this fundamental limit. BLISS-SPICA provide a line sensitivity of 10^-20 W m^-2 , thereby enabling spectroscopy of dust-obscured galaxies at all epochs back to the first billion years after the Big Bang (redshift 6), and study of all stages of planet formation in circumstellar disks. BLISS covers the 35-430 micron waveband at moderate resolving power (300<R<700) in six grating spec­ trometer bands, each coupling at least two 2 sky positions simultaneously. The instrument is cooled with an on-board refrigerator to 50 mK for optimal sensitivity. The detector package in the goal implementation is 4200 silicon-nitride micro-mesh leg-isolated bolometers with superconducting transition-edge-sensed (TES) thermis­ tors, read out with a cryogenic time-domain multiplexer. The instrument is designed to fit within the stringent SPICA resource allocations for mass and heat lift, and to mitigate the impact of cosmic rays. We report on this design and our progress in prototyping and validating the BLISS spectrometers and prototype cooler. A companion paper in Conference 8452 (A. Beyer et al.) discusses in greater detail the progress in the BLISS TES bolometer development.

SPICA (Space Infrared Telescope for Cosmology and Astrophysics) is an astronomical mission optimized for mid- and far-infrared astronomy, envisioned for launch in early 2020s. The core wavelength coverage of this mission is 5 to 200 micron. Mid-infrared Camera and Spectrometer (MCS) will provide imaging and spectroscopic observing capabilities in the mid-infrared region with 4 modules. WFC (Wide Field Camera) has two 5 arcminutes square field of view and covers the wavelength range from 5 to 38 micron. MRS (Mid Resolution Spectrometer) has integral field units by image slicer and covers the wavelength range from 12.2 to 37.5 micron simultaneously using dichroic filter and two sets of spectrometers. HRS (High Resolution Spectrometer) covers the wavelength range from 12 to 18 micron with resolving power 20000 to 30000, and it has optional short wavelength channel which covers from 4 to 8 micron with resolving power 30000. LRS (Low Resolution Spectrometer) adopts prism disperser and covers the wavelength range from 5 to 38 micron with resolving power 50 to 100. Here, we present detailed specifications of MCS, optical design, and estimated performance on orbit.

The Japanese SPace Infrared telescope for Cosmology and Astrophysics, SPICA, will provide astronomers with a long awaited new window on the universe. Having a large cold telescope cooled to only 6K above absolute zero, SPICA will provide a unique environment where instruments are limited only by the cosmic background itself. A consortium of European and Canadian institutes has been established to design and implement the SpicA FAR infrared Instrument SAFARI, an imaging spectrometer designed to fully exploit this extremely low far infrared background environment provided by the SPICA observatory. SAFARI’s large instantaneous field of view combined with the extremely sensitive Transition Edge Sensing detectors will allow astronomers to very efficiently map large areas of the sky in the far infrared – in a square degree survey of a 1000 hours many thousands of faint sources will be detected, and a very large fraction of these sources will be fully spectroscopically characterised by the instrument. Efficiently obtaining such a large number of complete spectra is essential to address several fundamental questions in current astrophysics: how do galaxies form and evolve over cosmic time?, what is the true nature of our own Milky Way?, and why and where do planets like those in our own solar system come into being?

The Safari instrument on the Japanese SPICA mission is a zodiacal background limited imaging spectrometer offering a photometric imaging (R ≈ 2), and a low (R = 100) and medium spectral resolution (R = 2000 at 100 μm) spectroscopy mode in three photometric bands covering the 34-210 μm wavelength range. The instrument utilizes Nyquist sampled filled arrays of very sensitive TES detectors providing a 2’x2’ instantaneous field of view. The all-reflective optical system of Safari is highly modular and consists of an input optics module containing the entrance shutter, a calibration source and a pair of filter wheels, followed by an interferometer and finally the camera bay optics accommodating the focal-plane arrays. The optical design is largely driven and constrained by volume inviting for a compact three-dimensional arrangement of the interferometer and camera bay optics without compromising the optical performance requirements associated with a diffraction- and background-limited spectroscopic imaging instrument. Central to the optics we present a flexible and compact non-polarizing Mach-Zehnder interferometer layout, with dual input and output ports, employing a novel FTS scan mechanism based on magnetic bearings and a linear motor. In this paper we discuss the conceptual design of the focal-plane optics and describe how we implement the optical instrument functions, define the photometric bands, deal with straylight control, diffraction and thermal emission in the long-wavelength limit and interface to the large-format FPA arrays at one end and the SPICA telescope assembly at the other end.

Euclid is a space-borne survey mission developed and operated by ESA. It is designed to understand the origin of the Universe's accelerating expansion. Euclid will use cosmological probes to investigate the nature of dark energy, dark matter and gravity by tracking their observational signatures on the geometry of the Universe and on the history of structure formation. The mission is optimised for the measurement of two independent cosmological probes: weak gravitational lensing and galaxy clustering. The payload consists of a 1.2 m Korsch telescope designed to provide a large field of view. The light is directed to two instruments provided by the Euclid Consortium: a visual imager (VIS) and a near-infrared spectrometer-photometer (NISP). Both instruments cover a large common field of view of 0.54 deg², to be able to survey at least 15,000 deg² for a nominal mission of 6 years. An overview of the mission will be presented: the scientific objectives, payload, satellite, and science operations. We report on the status of the Euclid mission with a foreseen launch in 2019.

Euclid-VIS is a large format visible imager for the ESA Euclid space mission in their Cosmic Vision program, scheduled for launch in 2019. Together with the near infrared imaging within the NISP instrument it forms the basis of the weak lensing measurements of Euclid. VIS will image in a single r+i+z band from 550-900 nm over a field of view of ~0.5 deg². By combining 4 exposures with a total of 2240 sec, VIS will reach to V=24.5 (10σ) for sources with extent ~0.3 arcsec. The image sampling is 0.1 arcsec. VIS will provide deep imaging with a tightly controlled and stable point spread function (PSF) over a wide survey area of 15000 deg² to measure the cosmic shear from nearly 1.5 billion galaxies to high levels of accuracy, from which the cosmological parameters will be measured. In addition, VIS will also provide a legacy imaging dataset with an unprecedented combination of spatial resolution, depth and area covering most of the extra-Galactic sky. Here we will present the results of the study carried out by the Euclid Consortium during the Euclid Definition phase.

The Euclid mission objective is to map the geometry of the dark Universe by investigating the distance-redshift relationship and the evolution of cosmic structures. The NISP (Near Infrared Spectro-Photometer) is one of the two Euclid instruments operating in the near-IR spectral region (0.9-2μm). The instrument is composed of: - a cold (140K) optomechanical subsystem constituted by a SiC structure, an optical assembly, a filter wheel mechanism, a grism wheel mechanism, a calibration unit and a thermal control - a detection subsystem based on a mosaic of 16 Teledyne HAWAII2RG 2.4μm. The detection subsystem is mounted on the optomechanical subsystem structure - a warm electronic subsystem (280K) composed of a data processing / detector control unit and of an instrument control unit. This presentation will describe the architecture of the instrument, the expected performance and the technological key challenges. This paper is presented on behalf of the Euclid Consortium.

The ESA/EUCLID satellite is equipped with two instruments that are simultaneously observing patches of > 0:5 square degree on the sky. The VIS visual light high spacial resolution imager and the NISP near infrared spectrometer and photometer are separated by a di-chroic beam splitter. This paper shows the baseline concept of the NISP instrument with its two observational modes being low resolution slit-less spectroscopy and three band J, H and K+ photometry. The drivers for the optical design, the nominal performance as well as the tolerancing approach for NISP are being presented. The impact of the tolerance approach and the tight tolerances on the opto-mechanical design, assembly, integration and verification is addressed in a special section of this paper.

The ESA mission Euclid is designed to explore the dark side of the Universe and to understand the nature of the dark energy responsible of the accelerating expansion of the Universe. One of the two probes carried by this mission is based on the Baryonic Acoustic Oscillation (BAO) method that requires the redshift measurements of millions of galaxies. In the Euclid design the spectroscopic channel uses slitless low resolution grisms. Classical grisms, manufactured by replication of a ruled master on the hypotenuse of a prism, are extremely difficult to make for Euclid due to the combination of low groove density and small blaze angle. Two years ago we started an RandD program to develop grisms by the photolithography process that is well adapted to coarse gratings and allows introducing aberration correction by ruling curved and non parallel grooves. During the Euclid Phase A, we developed several prototypes made by photolithography and we present in this paper the test results done in the specific environment of the Euclid mission.

Euclid is an ESA Cosmic-Vision wide-field-space mission which is designed to explain the origin of the acceleration of Universe expansion. The mission will investigate at the same time two primary cosmological probes: Weak gravitational Lensing (WL) and Galaxy Clustering (in particular Baryon Acoustic Oscillations, BAO). The extreme precision requested on primary science objectives can only be achieved by observing a large number of galaxies distributed over the whole sky in order to probe the distribution of dark matter and galaxies at all scales. The extreme accuracy needed requires observation from space to limit all observational biases in the measurements. The definition of the Euclid survey, aiming at detecting billions of galaxies over 15 000 square degrees of the extragalactic sky, is a key parameter of the mission. It drives its scientific potential, its duration and the mass of the spacecraft. The construction of a Reference Survey derives from the high level science requirements for a Wide and a Deep survey. The definition of a main sequence of observations and the associated calibrations were indeed a major achievement of the Definition Phase. Implementation of this sequence demonstrated the feasibility of covering the requested area in less than 6 years while taking into account the overheads of space segment observing and maneuvering sequence. This reference mission will be used for sizing the spacecraft consumables needed for primary science. It will also set the framework for optimizing the time on the sky to fulfill the primary science and maximize the Euclid legacy.

In this paper we develop methods to use a linear optical model to capture the field dependence of wavefront aberrations in a nonlinear optimization-based phase retrieval algorithm for image-based wavefront sensing. The linear optical model is generated from a ray trace model of the system and allows the system state to be described in terms of mechanical alignment parameters rather than wavefront coefficients. This approach allows joint optimization over images taken at different field points and does not require separate convergence of phase retrieval at individual field points. Because the algorithm exploits field diversity, multiple defocused images per field point are not required for robustness. Furthermore, because it is possible to simultaneously fit images of many stars over the field, it is not necessary to use a fixed defocus to achieve adequate signal-to-noise ratio despite having images with high dynamic range. This allows high performance wavefront sensing using in-focus science data. We applied this technique in a simulation model based on the Wide Field Infrared Survey Telescope (WFIRST) Intermediate Design Reference Mission (IDRM) imager using a linear optical model with 25 field points. We demonstrate sub-thousandth-wave wavefront sensing accuracy in the presence of noise and moderate undersampling for both monochromatic and polychromatic images using 25 high-SNR target stars. Using these high-quality wavefront sensing results, we are able to generate upsampled point-spread functions (PSFs) and use them to determine PSF ellipticity to high accuracy in order to reduce the systematic impact of aberrations on the accuracy of galactic ellipticity determination for weak-lensing science.

This paper presents the GWA and the Compensating mechanism of the Near Infrared SpectroPhotometer (NISP) instrument of the ESA Euclid mission. The NIS instrument should perform an exposure sequence in the wave­ length range [0.9 - 2.0Jum with different exposures of the same field of views with different passband grisms with two orthogonal dispersion directions and two wavelength range. These functionalities will be achieved by a mechanism supporting the optical elements: the Grism Wheel Assembly (GWA). The required positioning repeatability is in the order of few arcsec to keep the spectra aligned with the detector pixel columns/rows. The GWA will be assembled to the NISP Optomechanical Assembly (NIOMA) with an operating temperature of 140K. A further mechanism is necessary to compensate the torque perturbances induced by the two large wheels. It is based onto a stepper motor that will drive a flywheel.

AKARI, the Japanese satellite mission dedicated to infrared astronomy was launched in 2006 February and exhausted its liquid helium in 2007 August. During the cold mission phase, the Infrared Camera (IRC) onboard carried out an all-sky survey at 9 and 18µm with better spatial resolution and higher sensitivity than IRAS. Both bands also have slightly shorter wavelength coverage than IRAS 12 and 25μm bands and thus provide different information on the infrared sky. All-sky image data of the IRC are now in the final processing and will be released to the public within a year. After the exhaustion of the cryogen, the telescope and focal plane instruments of AKARI had still been kept at sufficiently low temperatures owing to the onboard cryocooler. Near-infrared (NIR) imaging and spectroscopic observations with the IRC had continued until 2011 May, when the spacecraft had a serious problem in the power supply system that forced us to terminate the observation. The IRC carried out nearly 20000 pointing observations in total despite of its near-earth orbit. About a half of them were performed after the exhaustion of the cryogen in the spectroscopic modes, which provided high-sensitivity NIR spectra from 2 to 5µm without disturbance of the terrestrial atmosphere. During the warm mission phase, the temperature of the instrument gradually increased and changed the array operation conditions. We present a summary of AKARI/IRC observations, including the all-sky mid-infrared diffuse data as well as the data taken in the warm mission phase.

We describe a mission architecture designed to substantially increase the science capability of the NASA Science Mission Directorate (SMD) Astrophysics Explorer Program for all AO proposers working within the near-UV to far-infrared spectrum. We have demonstrated that augmentation of Falcon 9 Explorer launch services with a 13 kW Solar Electric Propulsion (SEP) stage can deliver a 700 kg science observatory payload to extra-Zodiacal orbit. This new capability enables up to ~13X increased photometric sensitivity and ~160X increased observing speed relative to a Sun- Earth L2, Earth-trailing, or Earth orbit with no increase in telescope aperture. All enabling SEP stage technologies for this launch service augmentation have reached sufficient readiness (TRL-6) for Explorer Program application in conjunction with the Falcon 9. We demonstrate that enabling Astrophysics Explorers to reach extra-zodiacal orbit will allow this small payload program to rival the science performance of much larger long development time systems; thus, providing a means to realize major science objectives while increasing the SMD Astrophysics portfolio diversity and resiliency to external budget pressure. The SEP technology employed in this study has strong applicability to SMD Planetary Science community-proposed missions. SEP is a stated flight demonstration priority for NASA's Office of the Chief Technologist (OCT). This new mission architecture for astrophysics Explorers enables an attractive realization of joint goals for OCT and SMD with wide applicability across SMD science disciplines.

The Cosmological Advanced Survey Telescope for Optical and UV Research (CASTOR) is a proposed CSA mission that would make a unique, powerful, and lasting contribution to astrophysics by providing panoramic, high-resolution imaging in the UV/optical (0.15 - 0.55 μm) spectral region. This versatile `smallSAT'-class mission would far surpass any ground-based optical telescope in terms of angular resolution, and would provide ultra-deep imaging in three broad lters to supplement longer-wavelength data from planned international dark energy missions (Euclid, WFIRST) as well as from the ground-based Large Synoptic Survey Telescope (LSST). Combining the largest focal plane ever own in space, with an innovative optical design that delivers HST-quality images over a eld two orders of magnitude larger than Hubble Space Telescope (HST), CASTOR would image about 1/8th of the sky to a (u-band) depth ~1 magnitude fainter than will be possible with LSST even after a decade of operations. No planned or proposed astronomical facility would exceed CASTOR in its potential for discovery at these wavelengths.

LiteBIRD [Lite (Light) satellite for the studies of B-mode polarization and Inflation from cosmic background Radiation Detection] is a small satellite to map the polarization of the cosmic microwave background (CMB) radiation over the full sky at large angular scales with unprecedented precision. Cosmological inflation, which is the leading hypothesis to resolve the problems in the Big Bang theory, predicts that primordial gravitational waves were created during the inflationary era. Measurements of polarization of the CMB radiation are known as the best probe to detect the primordial gravitational waves. The LiteBIRD working group is authorized by the Japanese Steering Committee for Space Science (SCSS) and is supported by JAXA. It has more than 50 members from Japan, USA and Canada. The scientific objective of LiteBIRD is to test all the representative inflation models that satisfy single-field slow-roll conditions and lie in the large-field regime. To this end, the requirement on the precision of the tensor-to-scalar ratio, r, at LiteBIRD is equal to or less than 0.001. Our baseline design adopts an array of multi-chroic superconducting polarimeters that are read out with high multiplexing factors in the frequency domain for a compact focal plane. The required sensitivity of 1.8μKarcmin is achieved with 2000 TES bolometers at 100mK. The cryogenic system is based on the Stirling/JT technology developed for SPICA, and the continuous ADR system shares the design with future X-ray satellites.

WISH, Wide-field Imaging Surveyor for High-redshiftt, is a space mission concept to conduct very deep and widefield surveys at near infrared wavelength at 1-5μm to study the properties of galaxies at very high redshift beyond the epoch of cosmic reionization. The concept has been developed and studied since 2008 to be proposed for future JAXA/ISAS mission. WISH has a 1.5m-diameter primary mirror and a wide-field imager covering 850 arcmin². The pixel scale is 0.155 arcsec for 18μm pitch, which properly samples the diffraction-limited image at 1.5μm. The main program is Ultra Deep Survey (UDS) covering 100 deg² down to 28AB mag at least in five broad bands. We expect to detect <10⁴ galaxies at z=8-9, 10³-10⁴ galaxies at z=11-12, and 50-100 galaxies at z<14, many of which can be feasible targets for deep spectroscopy with Extremely Large Telescopes. With recurrent deep observations, detection and light curve monitoring for type-Ia SNe in rest-frame infrared wavelength is also conducted, which is another main science goal of the mission. During the in-orbit 5 years observations, we expect to detect and monitor <2000 type-Ia SNe up to z~2. WISH also conducts Ultra Wide Survey, covering 1000deg² down to 24-25AB mag as well as Extreme Survey, covering a limited number of fields of view down to 29-30AB mag. We here report the progress of the WISH project including the basic telescope and satellite design as well as the results of the test for a proto-model of the flip-type filter exchanger which works robustly near 100K.

The i-INSPIRE satellite is the result of a collaborative project at the University of Sydney, across the science and engineering faculties. The satellite is a compact tube-shaped pico-satellite with a mass of less than 0.75 kg. i-INSPIRE carries three science instruments - a photonic spectrograph, a radiation counter and an imaging camera, and will be launched to a 310km polar orbit in late 2012 or early 2013. Here we describe the satellite and its subsystems (including the science instruments and the communication system) as well as the ground station, pre-launch tests, and the proposed launch itself. i-INSPIRE will be Australia's first fully university operated pico-satellite.

We are currently constructing FalconSAT-7 for launch in mid-2014. The low-Earth, 3U CubeSat solar telescope incorporates a 0.2m deployable membrane photon sieve with over 2.5 billion holes. The aim of the experiment is to demonstrate diffraction limited imaging of a collapsible, diffractive primary over a narrow bandwidth. As well as being simpler to manufacture and deploy than curved, polished surfaces, the sheets do not have to be optically flat, greatly reducing many engineering issues. As such, the technology is particularly promising as a means to achieve extremely large optical primaries from compact, lightweight packages.

We present here a conceptual design of a near infrared survey satellite whose primary goal is to carry out an all sky survey of Polycyclic Aromatic Hydrocarbons (PAH). The searching of PAH is through direct imaging both at and besides its 3.3 μm CH stretching vibrations emission bands and make comparison between the "line" and the continuum fluxes. The dawn-dust sun-synchronous orbit is chosen because it is ideal for thermal control and it is suitable for all sky surveys. The "pointing-maneuver-pointing" observing strategy is adopted in order to minimize the effect from the detector read noises. The survey sensitivity is chosen to generally match those of the UKIDSS near IR surveys so their results can be compared more directly.

We present EclipseSim, a radiometric model for exoplanet transit spectroscopy that allows easy exploration of the fundamental performance limits of any space-based facility aiming to perform such observations. It includes a library of stellar model atmosphere spectra and can either approximate exoplanet spectra by simplified models, or use any theoretical or observed spectrum, to simulate observations. All calculations are done in a spectrally resolved fashion and the contributions of the various fundamental noise sources are budgeted separately, allowing easy assessment of the dominant noise sources, as a function of wavelength. We apply EclipseSim to the Exoplanet Characterization Observatory (EChO), a proposed mission dedicated to exoplanet transit spectroscopy that is currently in competition for the M3 launch slot of ESA’s cosmic vision programme. We show several case studies on planets with sizes in the super-Earth to Jupiter range, and temperatures ranging from the temperate to the ≈1500K regime, demonstrating the power and versatility of EChO. EclipseSim is publicly available.^*

The Exoplanet Characterisation Observatory (EChO) is a space mission dedicated to undertaking spectroscopy of transiting exoplanets over the widest wavelength range possible. It is based around a highly stable space platform with a 1.2 m class telescope. The mission is currently being studied by ESA in the context of a medium class mission within the Cosmic Vision programme for launch post 2020. The payload suite is required to provide simultaneous coverage from the visible to the mid-infrared and must be highly stable and effectively operate as a single instrument. In this paper we describe the integrated spectrometer payload design for EChO which will cover the 0.4 to 16 micron wavelength band. The instrumentation is subdivided into 5 channels (Visible/Near Infrared, Short Wave InfraRed, 2 x Mid Wave InfraRed; Long Wave InfraRed) with a common set of optics spectrally dividing the input beam via dichroics. We discuss the significant design issues for the payload and the detailed technical trade-offs that we are undertaking to produce a payload for EChO that can be built within the mission and programme constraints and yet which will meet the exacting scientific performance required to undertake transit spectroscopy.

The Exoplanet Characterisation Observatory (EChO) is a medium class mission candidate within ESA's Cosmic Vision 2015-2025 program on space science. EChO will be equipped with a visible to infrared spectrometer covering the wavelength range from 0.4 - 11 μm (goal: 16 μm) at a spectral resolving power between 30 and 300 in order to characterize the atmospheres of known transiting extrasolar planets ranging from Hot Jupiters to Super Earths. In this paper we will present first results from the dedicated study of the EChO science payload carried out by our EChO Instrument Consortium during the assessment phase of the mission.

In this paper, we present the design of the MWIR channels of EChO. Two channels cover the 5-11 micron spectral range. The choice of the boundaries of each channel is a trade-off driven by the science goals (spectral features of key molecules) and several parameters such as the common optics design, the dichroic plates design, the optical materials characteristics, the detector cut-off wavelength. We also will emphasize the role of the detectors choice that drives the thermal and mechanical designs and the cooling strategy.

The technology of Atomic Layer Deposition (ALD) holds promise to enable a future strategic mission that can address both ultraviolet (UV) astrophysics and optical exoplanet science with a shared telescope. The technology path to a shared telescope requires the development of a mirror coating with high reflectance from 100 nm to 1000 nm, and low polarization effects (i.e., s-p phase shifts that can vary with angle of incidence across a primary and secondary mirror) in the optical range. Currently, UV coatings have low reflectance, and conventional optical coatings have poor polarization properties for high-contrast coronagraph applications. In this paper we attempt to take a first step toward solving both problems simultaneously by using ALD, taking advantage of the fact that ALD can potentially produce mirror coatings with denser layers than conventional coatings (hence better reflectance, durability, and water resistance). In addition, ALD can potentially produce coatings with new composite materials (hence better control of polarization). We report here the results of our initial experiments with mirror coatings using ALD.

We present the thermal sieve, which is a diffractive baffle that provides thermal isolation between an ambient collimator and a cryogenic optical system being measured. The baffle uses several parallel plates with holes in them. The holes are lined up to allow the collimated light to pass, but the view factor for thermal radiation is greatly reduced. A particular design is shown here that allows less than 0.25 W/m² thermal transfer and degrades the test wavefront by only 3 nm rms.

The Stereo Camera (STC) of the SIMBIO-SYS imaging suite of the BepiColombo ESA mission to Mercury is based on an innovative and compact design in which the light independently collected by two optical channels at ±20° separation with respect to nadir falls on a common bidimensional detector. STC adopts a novel stereo acquisition mode, based on the push-frame concept, never used before on a space mission. To characterize this camera for obtaining the most accurate data of the Mercury surface, standard calibration measurements have been performed. In addition, we also wanted to demonstrate and characterize the capability of the instrument to reconstruct a 3D surface with the desired accuracy by means of the stereo push-frame concept. To this end, a lab setup has been realized with an evaluation model of STC, in which the problem of working at an essentially infinite object distance over hundred km baselines has been overcome by means of a simple collimator and two precision rotators. The intrinsic and extrinsic parameters of the camera have been obtained with standard stereo procedures, adapted to the specific case. The stereo validation has been performed by comparing the shape of the target object accurately measured by laser scanning, with the shape reconstructed by applying the adopted stereo algorithm to the acquired image pairs. The obtained results show the goodness of this innovative validation technique, that will be applied also for validating the stereo capabilities of STC flight model.

Medium to large angle observations, e.g. for global astrometry, can be implemented in space by means of either a common telescope, fed by a Beam Combiner (as in Hipparcos), or by individual telescopes set in a rigid geometry (as in Gaia). We investigate the applicability of auto-collimation and cophasing techniques for implementation of a monitoring system alternative to more conventional point-to-point metrology. Apart different implementation constraints, the most relevant difference consists in the auto-collimation approach characteristics of monitoring simultaneously comparably large sections of the optical system, thus evaluating collective properties closer to those experienced by the stellar beams.

ESA´s astrometry satellite Gaia is scheduled for launch in 2013. In a combination of outstanding hardware performance, autonomous object detection and sophisticated data processing, Gaia will chart more than a billion stars of the entire sky to unprecedented accuracy during its 5 years mission. A key element to its mission success is the focal plane assembly (FPA), the largest ever flown to space, comprising a close-butted almost Giga-pixel mosaic of 106 large area CCDs. Manufacturing and extensive testing of the individual devices and detector system units as well as integration on the single-piece, silicon-carbide support structure has been a challenge. The focal plane is now assembled and has undergone its final tests during 2012. The paper summarizes the expected in-flight performances of Gaia´s FPA and the implemented tools and procedures to monitor its operation in space. Accurate knowledge of the impact of FPA performance parameters on individual measurements and its evolution in time is critical to achieve the high accuracy needed in calibrating the science data. An example is the radiation-induced deterioration of the CCD charge transfer efficiency, which acts on distorting the detected object PSFs while observing the sky in continuous scan mode. Through dedicated calibration procedures and directly through the scientific data processing, Gaia will therefore closely track the radiation environment at L2 from the FPA output itself. Detection of transient effects and analysis of persistent damage on the CCDs mainly caused by solar protons converts Gaia's FPA inherently into the largest ever radiation monitor in space.

The ESA Gaia spacecraft has two Shack-Hartmann wavefront sensors (WFS) on its focal plane. They are required to refocus the telescope in-orbit due to launch settings and gravity release. They require bright stars to provide good signal to noise patterns. The centroiding precision achievable poses a limit on the minimum stellar brightness required and, ultimately, on the observing time required to reconstruct the wavefront. Maximum likelihood algorithms have been developed at the Gaia SOC. They provide optimum performance according to the Crámer-Rao lower bound. Detailed wavefront reconstruction procedures, dealing with partial telescope pupil sampling and partial microlens illumination have also been developed. In this work, a brief overview of the WFS and an in depth description of the centroiding and wavefront reconstruction algorithms is provided.

The Gaia mission will create an extraordinarily precise three-dimensional map of more than one billion stars in our Galaxy. The Gaia spacecraft, built by EADS Astrium, is part of ESA's Cosmic Vision programme and scheduled for launch in 2013. Gaia measures the position, distance and motion of stars with an accuracy of 24 micro-arcsec using two telescopes at a fixed mutual angle of 106.5°, named the ‘Basic Angle’. This accuracy requires ultra-high stability, which can only be achieved by using Silicon Carbide for both the optical bench and the telescopes. TNO has developed, built and space qualified the Silicon carbide Basic Angle Monitoring (BAM) on-board metrology system for this mission. The BAM measures the relative motion of Gaia’s telescopes with accuracies in the range of 0.5 micro-arcsec. This is achieved by a system of two laser interferometers able to measure Optical Path Differences (OPD) as small as 1.5 picometer rms. Following a general introduction to the Gaia mission, the Payload Module (PLM) and the use of Silicon Carbide as base material, this presentation will address an overview of the challenges towards the key requirements, design, integration and testing (including space-level qualification) of the Gaia BAM.

We present an overview of the EXoplanetary Circumstellar Environments and Disk Explorer (EXCEDE), selected by NASA for technology development and maturation. EXCEDE will study the formation, evolution and architectures of exoplanetary systems, and characterize circumstellar environments into stellar habitable zones. EXCEDE provides contrast-limited scattered-light detection sensitivities ~ 1000x greater than HST or JWST coronagraphs at a much smaller effective inner working angle (IWA), thus enabling the exploration and characterization of exoplanetary circumstellar disks in currently inaccessible domains. EXCEDE will utilize a laboratory demonstrated high-performance Phase Induced Amplitude Apodized Coronagraph (PIAA-C) integrated with a 70 cm diameter unobscured aperture visible light telescope. The EXCEDE PIAA-C will deliver star-to-disk augmented image contrasts of < 10E-8 and a 1.2 λ/D IWA or 0.14” with a wavefront control system utilizing a 2000-element MEMS DM and fast steering mirror. EXCEDE will provide 0.12” spatial resolution at 0.4 μm with dust detection sensitivity to levels of a few tens of zodis with two-band imaging polarimetry. EXCEDE is a science-driven technology pathfinder that will advance our understanding of the formation and evolution of exoplanetary systems, placing our solar system in broader astrophysical context, and will demonstrate the high contrast technologies required for larger-scale follow-on and multi-wavelength investigations on the road to finding and characterizing exo-Earths in the years ahead.

The infrastructure available on the ISS provides a unique opportunity to develop the technologies necessary to assemble large space telescopes. Assembling telescopes in space is a game-changing approach to space astronomy. Using the ISS as a testbed enables a concentration of resources on reducing the technical risks associated with integrating the technologies, such as laser metrology and wavefront sensing and control (WFSandC), with the robotic assembly of major components including very light-weight primary and secondary mirrors and the alignment of the optical elements to a diffraction-limited optical system in space. The capability to assemble the optical system and remove and replace components via the existing ISS robotic systems such as the Special Purpose Dexterous Manipulator (SPDM), or by the ISS Flight Crew, allows for future experimentation as well as repair if necessary. In 2015, first light will be obtained by the Optical Testbed and Integration on ISS eXperiment (OpTIIX), a small 1.5-meter optical telescope assembled on the ISS. The primary objectives of OpTIIX include demonstrating telescope assembly technologies and end-to-end optical system technologies that will advance future large optical telescopes.

The Wide Field Infrared Survey Telescope (WFIRST) mission concept was ranked first in new space astrophysics missions by the Astro2010 Decadal Survey, incorporating the Joint Dark Energy Mission payload concept and multiple science white papers. This mission is based on a space telescope at L2 studying exoplanets [via gravitational microlensing], probing dark energy, and surveying the near infrared sky. Since the release of the Astro2010 Decadal Survey, the team has been working with the WFIRST Science Definition Team to refine mission and payload concepts. We present the current interim reference mission point design of the payload, based on the use of a 1.3m unobscured aperture three mirror anastigmat form, with focal imaging and slit-less spectroscopy science channels. We also present the first results of Structural/Thermal/Optical performance modeling of the telescope point design.

The WFC3 is the primary science instrument on HST. It accounts for over half of all observations since its installation during SM4 in May 2009. We discuss the evolution of our understanding of the performance of WFC3 and our calibration strategies. A key aspect of WFC3 is its high degree of stability which permits steadily improving calibrations. We discuss four main topics: the calibration and trending of photometric and astrometric observations, the techniques we are using to achieve markedly improved flat field calibrations (and their associated challenges), the evolution of the WFC3 CCD and HgCdTe detectors in the space environment, and the recent implementation of a spatial scanning observing technique which enables very high signal to noise ratio observations of bright sources including exo-planets and also high precision astrometry.

Like essentially all IR arrays, the IR detector in the Wide Field Camera 3 (WFC3) instrument on-board Hubble Space Telescope (HST) exhibits afterimages, known as persistence, following exposures to light levels that approach or exceed saturation of individual pixels of the detector. The nature of the persistence in the HgCdTe WFC3/IR detector is distinctly non-linear in that the amount of persistence is not simply proportional to the exposure level. Instead, the amount of persistence is small until the exposure reaches about half saturation at which point it rises fairly rapidly until the exposure reaches about twice saturation and then it increases gradually with increasing saturation. The persistence shows typical power law decay with time over the periods of time that are relevant to HST observations. Given the frequent usage of the WFC3/IR detector on HST, it is not possible to completely avoid the effects of persistence in observations obtained with HST by introducing time gaps between IR observations. Therefore, we have developed a parameterized persistence model that we are using to estimate the amount of persistence in all WRC3/IR images. These estimates are available for all existing WFC3/IR images through the Mikulski Archive at STScI (MAST) to help HST users remove persistence from their images. Here we discuss the characterization of persistence in the WFC3 detector in orbit, the fraction of observations that are affected by persistence, and the effectiveness of the tools we have developed to reduce the effects of persistence in WFC3 images.

The dominant non-instrumental background source for space-based infrared observatories is the zodiacal light (ZL). We present Spitzer Infrared Array Camera (IRAC) measurements of the ZL at 3.6, 4.5, 5.8, and 8.0 μm, taken as part of the instrument calibrations. We measure the changing surface brightness levels in approximately weekly IRAC observations near the north ecliptic pole over the period of roughly 8.5 years. This long time baseline is crucial for measuring the annual sinusoidal variation in the signal levels due to the tilt of the dust disk with respect to the ecliptic, which is the true signal of the ZL. This is compared to both Cosmic Background Explorer Diffuse Infrared Background Experiment data and a ZL model based thereon. Our data show a few percent discrepancy from the Kelsall et al.(1998)¹ model including a potential warping of the interplanetary dust disk and a previously detected overdensity in the dust cloud directly behind the Earth in its orbit. Accurate knowledge of the ZL is important for both extragalactic and Galactic astronomy including measurements of the cosmic infrared background, absolute measures of extended sources, and comparison to extrasolar interplanetary dust models. IRAC data can be used to further inform and test future ZL models.

The Infrared Array Camera (IRAC) on the Spitzer Space Telescope has been used to measure < 10^-4 temporal variations in point sources (such as transiting extrasolar planets) at 3.6 and 4.5 μm. Due to the under-sampled nature of the PSF, the warm IRAC arrays show variations of as much as 8% in sensitivity as the center of the PSF moves across a pixel due to normal spacecraft pointing wobble and drift. These intra-pixel gain variations are the largest source of correlated noise in IRAC photometry. Usually this effect is removed by fitting a model to the science data themselves (self-calibration), which could result in the removal of astrophysically interesting signals. We describe a new technique for significantly reducing the gain variations and improving photometric precision in a given observation, without using the data to be corrected. This comprises: (1) an adaptive centroiding and repositioning method ("Peak-Up") that uses the Spitzer Pointing Control Reference Sensor (PCRS) to repeatedly position a target to within 0.1 IRAC pixels of an area of minimal gain variation; and (2) the high-precision, high-resolution measurement of the pixel gain structure using non-variable stars. We show that the technique currently allows the reduction of correlated noise by almost an order of magnitude over raw data, which is comparable to the improvement due to self-calibration. We discuss other possible sources of correlated noise, and proposals for reducing their impact on photometric precision.

Significant improvements in our understanding of various photometric effects have occurred in the more than nine years of flight operations of the Infrared Array Camera aboard the Spitzer Space Telescope. With the accumulation of calibration data, photometric variations that are intrinsic to the instrument can now be mapped with high fidelity. Using all existing data on calibration stars, the array location-dependent photometric correction (the variation of flux with position on the array) and the correction for intra-pixel sensitivity variation (pixel-phase) have been modeled simultaneously. Examination of the warm mission data enabled the characterization of the underlying form of the pixelphase variation in cryogenic data. In addition to the accumulation of calibration data, significant improvements in the calibration of the truth spectra of the calibrators has taken place. Using the work of Engelke et al. (2006), the KIII calibrators have no offset as compared to the AV calibrators, providing a second pillar of the calibration scheme. The current cryogenic calibration is better than 3% in an absolute sense, with most of the uncertainty still in the knowledge of the true flux densities of the primary calibrators. We present the final state of the cryogenic IRAC calibration and a comparison of the IRAC calibration to an independent calibration methodology using the HST primary calibrators.

MADRAS (Mirror Active, Deformable and Regulated for Applications in Space) project aims at demonstrating the interest of Active Optics for space applications. We present the prototype of a 24 actuators, 100 mm diameter deformable mirror to be included in a space telescope's pupil relay to compensate for large lightweight primary mirror deformation. The mirror design has been optimized with Finite Element Analysis and its experimental performance characterized in representative conditions. The developed deformable mirror provides an efficient wave-front correction with a limited number of actuators and a design fitting space requirements.

The desire to field space-based telescopes with apertures in excess of 10 meter diameter is forcing the development of extreme lightweighted large optics. Sparse apertures, shell optics, and membrane optics are a few of the approaches that have been investigated and demonstrated. Membrane optics in particular have been investigated for many years. The majority of the effort in membrane telescopes has been devoted to using reflective membrane optics with a fair level of success being realized for small laboratory level systems; however, extending this approach to large aperture systems has been problematic. An alternative approach in which the membrane is used as a diffractive transmission element has been previously proposed, offering a significant relaxation in the control requirements on the membrane surface figure. The general imaging principle has been demonstrated in 50-cm-scale laboratory systems using thin glass and replicated membranes at long f-number (f/50). In addition, a 5-meter diameter f/50 transmissive diffractive optic has been demonstrated, using 50-cm scale segments arrayed in a foldable origami pattern. In this paper we discuss Membrane Optical Imager Real-time Exploitation (MOIRE) Phase 1 developments that culminated in the development and demonstration of an 80 cm diameter, off-axis, F/6.5 phase diffractive transmissive membrane optic. This is a precursor for an optic envisioned as one segment of a 10 meter diameter telescope. This paper presents the demonstrated imaging wavefront performance and collection efficiency of an 80 cm membrane optic that would be used in an F/6.5 primary, discusses the anticipated areal density in relation to existing space telescopes, and identifies how such a component would be used in previously described optical system architectures.

The spherical primary optical telescope (SPOT) project is an internal research and development program at NASA Goddard Space Flight Center. The goals of the program are to develop a robust and cost effective way to manufacture spherical mirror segments and demonstrate a new wavefront sensing approach for continuous phasing across the segmented primary. This paper focuses on the fabrication of the mirror segments. Significant cost savings were achieved through the design, since it allowed the mirror segments to be cast rather than machined from a glass blank. Casting was followed by conventional figuring at Goddard Space Flight Center. After polishing, the mirror segments were mounted to their composite assemblies. QED Technologies used magnetorheological finishing (MRF®) for the final figuring. The MRF process polished the mirrors while they were mounted to their composite assemblies. Each assembly included several magnetic invar plugs that extended to within an inch of the face of the mirror. As part of this project, the interaction between the MRF magnetic field and invar plugs was evaluated. By properly selecting the polishing conditions, MRF was able to significantly improve the figure of the mounted segments. The final MRF figuring demonstrates that mirrors, in the mounted configuration, can be polished and tested to specification. There are significant process capability advantes due to polishing and testing the optics in their final, end-use assembled state.

The far-IR astrophysics community is eager to follow up Spitzer and Herschel observations with sensitive, high-resolution imaging and spectroscopy, for such measurements are needed to understand merger-driven star formation and chemical enrichment in galaxies, star and planetary system formation, and the development and prevalence of water-bearing planets. The community is united in its support for a space-based interferometry mission. Through concerted efforts worldwide, the key enabling technologies are maturing. Two balloon-borne far-IR interferometers are presently under development. This paper reviews recent technological and programmatic developments, summarizes plans, and offers a vision for space-based far-IR interferometry involving international collaboration.

Parametric cost models can be used by designers and project managers to perform relative cost comparisons between major architectural cost drivers and allow high-level design trades; enable cost-benefit analysis for technology development investment; and, provide a basis for estimating total project cost between related concepts. This paper reports on recent revisions and improvements to our ground telescope cost model and refinements of our understanding of space telescope cost models. One interesting observation is that while space telescopes are 50X to 100X more expensive than ground telescopes, their respective scaling relationships are similar. Another interesting speculation is that the role of technology development may be different between ground and space telescopes. For ground telescopes, the data indicates that technology development tends to reduce cost by approximately 50% every 20 years. But for space telescopes, there appears to be no such cost reduction because we do not tend to re-fly similar systems. Thus, instead of reducing cost, 20 years of technology development may be required to enable a doubling of space telescope capability. Other findings include: mass should not be used to estimate cost; spacecraft and science instrument costs account for approximately 50% of total mission cost; and, integration and testing accounts for only about 10% of total mission cost.

A large aperture optical telescope is planned for the next Japanese solar mission SOLAR-C as one of major three observing instruments. The optical telescope is designed to provide high-angular-resolution investigation of lower atmosphere from the photosphere to the uppermost chromosphere with enhanced spectroscopic and spectro-polarimetric capability covering a wide wavelength region from 280 nm to 1100 nm. The opto-mechanical and -thermal performance of the telescope is crucial to attain high-quality solar observations and we present a study of optical and structural design of the large aperture space solar telescope, together with conceptual design of its accompanying focal plane instruments: wide-band and narrow-band filtergraphs and a spectro-polarimeter for high spatial and temporal observations in the solar photospheric and chromospheric lines useful for sounding physical condition of dynamical phenomena.

The LASCO-C2 coronagraph aboard SOHO (the SOlar and Heliospheric Observatory) is continuously observing the solar corona since early 1996. The instrument as well as the experimental context underwent during this period many changes and observational constraints. The consequences for the in-orbit calibration procedures are illustrated with the systematic measure of the coronagraph straylight. Disentangle the coronal signal and the straylight is the crucial point. The separation and monitoring of the straylight component rely on the daily sets of polarized observations of the corona and a minimal set of assumptions about the symmetry of the F-corona (the dust component of the solar corona). Four main changes have been detected since 1996. Specific recommendations for the in-orbit calibration of future spatial coronagraphs will be presented.

METIS (Multi Element Telescope for Imaging and Spectroscopy investigation), selected to fly aboard the Solar Orbiter ESA/NASA mission, is conceived to perform imaging (in visible, UV and EUV) and spectroscopy (in EUV) of the solar corona, by means of an integrated instrument suite located on a single optical bench and sharing the same aperture on the satellite heat shield. As every coronagraph, METIS is highly demanding in terms of stray light suppression. Coronagraphs history teaches that a particular attention must be dedicated to the occulter optimization. The METIS occulting system is of particular interest due to its innovative concept. In order to meet the strict thermal requirements of Solar Orbiter, METIS optical design has been optimized by moving the entrance pupil at the level of the external occulter on the S/C thermal shield, thus reducing the size of the external aperture. The scheme is based on an inverted external-occulter (IEO). The IEO consists of a circular aperture on the Solar Orbiter thermal shield. A spherical mirror rejects back the disk-light through the IEO. A breadboard of the occulting assembly (BOA) has been manufactured in order to perform stray light tests in front of two solar simulators (in Marseille, France and in Torino, Italy). A first measurement campaign has been carried on at the Laboratoire d'Astrophysique de Marseille. In this paper we describe the BOA design, the laboratory set-up and the preliminary results.

The science objectives of the James Webb Space Telescope fall into four themes. The End of the Dark Ages: First Light and Reionization theme seeks to identify the first luminous sources to form and to determine the ionization history of the universe. The Assembly of Galaxies theme seeks to determine how galaxies and the dark matter, gas, stars, metals, morphological structures, and black holes within them evolved from the epoch of reionization to the present. The Birth of Stars and Protoplanetary Systems theme seeks to unravel the birth and early evolution of stars, from infall onto dust-enshrouded protostars, to the genesis of planetary systems. The Planetary Systems and the Origins of Life theme seeks to determine the physical and chemical properties of planetary systems around nearby stars and of our own, and to investigate the potential for life in those systems. These four science themes were used to establish the design requirements for the observatory and instrumentation. Since Webb’s capabilities are unique, those science themes will remain relevant through launch and operations and goals contained within these themes will continue to guide the design and implementation choices for the mission. More recently, it has also become clear that Webb will make major contributions to other areas of research, including dark energy, dark matter, exoplanet characterization and Solar System objects. In this paper, I review the original four science themes and discuss how the scientific output of Webb will extend to these new areas of research.

The James Webb Space Telescope (JWST) will be a powerful space observatory whose four science instruments will deliver rich imaging and multiplexed spectroscopic datasets to the astronomical and planetary science communities. The ground segment for JWST, now being designed and built, will carry out JWST's science operations. The ground segment includes: software that the scientific community will use to propose and specify new observations; systems that will schedule science and calibration observations in a way that respects physical and investigator-specified constraints, while satisfying preferences for efficient observing, low background levels, and distributed subscription across a year; the infrastructure to regularly measure and maintain the telescope's wavefront; orbit determination, ranging, and tracking; communication via the Deep Space Network to command the observatory and retrieve scientific data; onboard scripts that execute each observing program in an event-driven fashion, with occasional interruptions for targets of opportunity or time-critical observations; and a system that processes and calibrates the data into science-ready products, automatically recalibrates when calibrations improve, and archives the data for timely access by the principal investigator and later worldwide access by the scientific community. This ground system builds on experience from operating the Hubble Space Telescope, while solving challenges that are unique to JWST. In this paper, we describe the elements of the JWST ground system, how it will work operationally from the perspective of the observatory itself, and how a typical user will interact with the system to turn their idea into scientific discovery.

The James Webb Space Telescope (JWST) is the largest cryogenic, space telescope ever built, and will address a broad range of scientific goals from first light in the universe and re-ionization, to characterization of the atmospheres of extrasolar planets. Recently, significant progress has been made in the construction of the observatory with the completion of all 21 flight mirrors that comprise the telescope’’s optical chain, and the start of flight instrument deliveries to the Goddard Space Flight Center. In this paper we discuss the design of the observatory, and focus on the recent milestone achievements in each of the major observatory sub-systems.

In a little under a decade, the James Webb Space Telescope (JWST) program has designed, manufactured, assembled and tested 21 flight beryllium mirrors for the James Webb Space Telescope Optical Telescope Element. This paper will summarize the mirror development history starting with the selection of beryllium as the mirror material and ending with the final test results. It will provide an overview of the technological roadmap and schedules and the key challenges that were overcome. It will also provide a summary of the key tests that were performed and the results of these tests.

The payload portion of James Web Space Telescope (JWST) consists of a deployable, three mirror anistigmat, telescope and an Integrated Science Instrument Model (ISIM) that contains the scientific instruments. This paper describes the overall process and strategy of aligning the Observatory in an efficient manner that reduces risk and strives to be tolerant of faults in the system. A process has been developed consisting of ground calibration of the instruments and alignment testing of the fixed optics to ensure that the telescope is alignable in space. The overall architecture of the alignment process and the processes to safely and efficiently conduct the optical commissioning is described.

Significant progress has been made in the development of the Optical Telescope Element (OTE) for the James Webb Space Telescope (JWST) Observatory. All of the mirror assemblies are complete and through final testing. The composite Pathfinder Primary Mirror Backplane Support Structure (PMBSS) has been completed and the flight structure is making significant progress. This paper will discuss the current status of all the OTE components and the plan forward to completion.

The performance of an optical system is best characterized by either the point spread function (PSF) or the optical transfer function (OTF). However, for system budgeting purposes, it is convenient to use a single scalar metric, or a combination of a few scalar metrics to track performance. For the James Webb Space Telescope, the Observatory level requirements were expressed in metrics of Strehl Ratio, and Encircled Energy. These in turn were converted to the metrics of total rms WFE and rms WFE within spatial frequency domains. The 18 individual mirror segments for the primary mirror segment assemblies (PMSA), the secondary mirror (SM), tertiary mirror (TM), and Fine Steering Mirror have all been fabricated. They are polished beryllium mirrors with a protected gold reflective coating. The statistical analysis of the resulting Surface Figure Error of these mirrors has been analyzed. The average spatial frequency distribution and the mirror-to-mirror consistency of the spatial frequency distribution are reported. The results provide insight to system budgeting processes for similar optical systems.

The James Webb Space Telescope optical telescope element mirror components, 18 individual primary mirror segment assemblies (PMSA), the secondary mirror (SM), tertiary mirror (TM), and Fine Steering Mirror, have all been fabricated. The performance of the optical telescope (OTE) based on the as-measured optical components is combined with alignment tolerances and the on-orbit alignment process to predict the imaging performance of JWST. The best estimate of the wavefront error, Strehl ratio and Encircled Energy stability is presented.

The James Webb Space Telescope (JWST) is a segmented deployable telescope, utilizing 6 degrees of freedom for adjustment of the Secondary Mirror (SM) and 7 degrees of freedom for adjustment of each of its 18 segments in the Primary Mirror (PM). When deployed, the PM segments and the SM will be placed in their correct optical positions to within a few mm, with accordingly large wavefront errors. The challenge, therefore, is to position each of these optical elements in order to correct the deployment errors and produce a diffraction-limited telescope, at λ=2μm, across the entire science field. This paper describes a suite of processes, algorithms, and software that has been developed to achieve this precise alignment, using images taken from JWST’s science instruments during commissioning. The results of flight-like end-to-end simulations showing the commissioning process are also presented.

The James Webb Space Telescope (JWST) telescope's secondary mirror and eighteen primary mirror segments are each actively controlled in rigid body position via six hexapod actuators. The mirrors are stowed to the mirror support structure to survive the launch environment and then must be deployed 12.5 mm to reach the nominally deployed position before the Wavefront Sensing and Control (WFSandC) alignment and phasing process begins. The actuation system is electrically, but not mechanically redundant. Therefore, with the large number of hexapod actuators, the fault tolerance of the OTE architecture and WFSandC alignment process has been carefully considered. The details of the fault tolerance will be discussed, including motor life budgeting, failure signatures, and motor life.

James Webb Space Telescope (JWST) Optical Telescope Element (OTE) mirror coating program has been completed. The science goals of the JWST mission require a uniform, low stress, durable optical coating with high reflectivity over the JWST spectral region. The coating has to be environmentally stable, radiation resistant and compatible with the cryogenic operating environment. The large size, 1.52 m point to point, light weight, beryllium primary mirror (PM) segments and flawless coating process during the flight mirror coating program that consisted coating of 21 flight mirrors were among many technical challenges. This paper provides an overview of the JWST telescope mirror coating program. The paper summarizes the coating development program and performance of the flight mirrors.

The James Webb Space Telescope (JWST) project has entered into a comprehensive integration and test (I and T) program that over the coming years will assemble and test the various elements of the observatory and verify the readiness of the integrated system for launch. Highlights of the I and T program include a sequence of cryo-vacuum tests of the Integrated Science Instrument Module (ISHvf), to be carried out at NASA's Goddard Space Flight Center (GSFC) and an end-to- end cryo-vacuum optical and thermal test - of unprecedented scale - of the telescope plus instruments at NASA's Johnson Space Center (JSC). The I and T program, as replanned for a 2018 launch readiness date, contains a number of risk-reduction features intended to maximize the prospects for success of the critical tests, leading to reduced cost and schedule risk for those activities. For the JSC test, these include enhancement of the precursor Pathfinder program, the addition of a second cryo-vacuum thermal test of the observatory's Core region, and enhancement of the subsystem level testing program for the cryo-cooler for the Mid-InfraRed Instrument (MlRl). We report here on the I and T program for JWST, focusing on the I and T path for the instruments and telescope, and on the status of the hardware and plans that support it.

The James Webb Space Telescope will undergo a full system test in the cryogenic vacuum chamber A at the Johnson Spaceflight Center in order to verify the overall performance of the combined telescope and instrument suite. This will be the largest and most extensive cryogenic test ever undertaken. Early in the test system development, it was determined that precise position measurements of the overall hardware would enhance the test results. Various concepts were considered before selecting photogrammetry for this metrology. Photogrammetry has been used in space systems for decades, however cryogenic use combined with the size and the optical/thermal sensitivity of JWST creates a unique set of implementation challenges. This paper provides an overview of the JWST photogrammetric system and mitigation strategies for three key engineering design challenges: 1) the thermal design of the viewing windows to prevent excessive heat leak and stray light to the test article 2) cost effective motors and mechanisms to provide the angle diversity required, and 3) camera-flash life and reliability sufficient for inaccessible use during the number and duration of the cryogenic tests.

The Integrated Science Instrument Module (ISIM) of the James Webb Space Telescope (JWST) is discussed from a systems perspective with emphasis on development status and advanced technology aspects. The ISIM is one of three elements that comprise the JWST space vehicle and is the science instrument payload of the JWST. The major subsystems of this flight element and their build status are described.

The Near-Infrared Camera (NIRCam) on the James Webb Space Telescope (JWST) offers revolutionary gains in sensitivity throughout the 1-5 μm region. NIRCam will enable great advances in all areas of astrophysics, from the composition of objects in our own Kuiper Belt and the physical properties of planets orbiting nearby stars to the formation of stars and the detection of the youngest galaxies in the Universe. NIRCam also plays an important role in initial alignment of JWST and the long term maintenance of its image quality. NIRCam is presently undergoing instrument Integration and Test in preparation for delivery to the JWST project. Key near-term milestones include the completion of cryogenic testing of the entire instrument; demonstration of scientific and wavefront sensing performance requirements; testing of replacement H2RG detectors arrays; and an analysis of coronagraphic performance in light of measured telescope wavefront characteristics. This paper summarizes the performance of NIRCam, the scientific and education/outreach goals of the science team, and some results of the on-going testing program.

The Near-Infrared Spectrograph NIRSpec is one of the four instruments of the James Webb Space Telescope (JWST). NIRSpec will cover the 0.6-5.0 micron range and will be capable of obtaining spectra of more than 100 objects simultaneously in its multi-object spectroscopy (MOS) mode. It also features a set of slits and an aperture for high contrast spectroscopy of individual sources, as well as an integral-field unit (IFU) for 3D spectroscopy. We will first show how these capabilities are linked to the four main JWST scientific themes. We will then give an overview of the NIRpec modes and spectral configurations with an emphasis on the layout of the field of view and of the spectra. Last, we will provide an update on the status of the instrument.

We report on the alignment verification activities using optical visible techniques, and performed at ambient temperature before and after environmental and qualification tests, on the Mid InfraRed Instrument (MIRI), one of the scientific instruments on-board the James Webb Space Telescope (JWST). More specifically, the method developed to measure some of the instrument key parameters, such as pupil shear and focus offset, is explained in details. We describe the chosen approach, the associated common hardware, the initial set-up and alignment, then discuss the measurements themselves and finally the data analysis, before concluding on the successful application of such approach to the optical characterization of the MIRI flight model.

The Fine Guidance Sensor (FGS) is one of the four science instruments on board the James Webb Space Telescope (JWST). FGS features two modules: an infrared camera dedicated to fine guiding of the observatory and a science camera module, the Near-Infrared Imager and Slitless Spectrograph (NIRISS) covering the wavelength range between 0.7 and 5.0 μm with a field of view of 2.2' X 2.2'. NIRISS has four observing modes: 1) broadband imaging featuring seven of the eight NIRCam broadband filters, 2) wide-field slitless spectroscopy at a resolving power of rv150 between 1 and 2.5 μm, 3) single-object cross-dispersed slitless spectroscopy enabling simultaneous wavelength coverage between 0. 7 and 2.5 μm at Rrv660, a mode optimized for transit spectroscopy of relatively bright (J > 7) stars and, 4) sparse aperture interferometric imaging between 3.8 and 4.8 μm enabling high­ contrast ("' 10^-4) imaging of M < 8 point sources at angular separations between 70 and 500 milliarcsec. This paper presents an overview of the FGS/NIRISS design with a focus on the scientific capabilities and performance offered by NIRISS.

The Aperture Masked Interferometry (AMI) mode on JWST-NIRISS is implemented as a 7-hole, 15% throughput, non-redundant mask (NRM) that operates with 5-8% bandwidth filters at 3.8, 4.3, and 4.8 microns. We present refined estimates of AMI's expected point-source contrast, using realizations of noise matched to JWST pointing requirements, NIRISS detector noise, and Rev-V JWST wavefront error models for the telescope and instrument. We describe our point-source binary data reduction algorithm, which we use as a standardized method to compare different observational strategies. For a 7.5 magnitude star we report a 10-a detection at between 8.7 and 9.2 magnitudes of contrast between 100 mas to 400 mas respectively, using closure phases and squared visibilities in the absence of bad pixels, but with various other noise sources. With 3% of the pixels unusable, the expected contrast drops by about 0.5 magnitudes. AMI should be able to reach targets as bright as M=5. There will be significant overlap between Gemini-GPI and ESO-SPHERE targets and AMI's search space, and a complementarity with NIRCam's coronagraph. We also illustrate synthesis imaging with AMI, demonstrating an imaging dynamic range of 25 at 100 mas scales. We tailor existing radio interferometric methods to retrieve a faint bar across a bright nucleus, and explain the similarities to synthesis imaging at radio wavelengths. Modest contrast observations of dusty accretion flows around AGNs will be feasible for NIRISS AMI. We show our early results of image-plane deconvolution as well. Finally, we report progress on an NRM-inspired approach to mitigate mission-level risk associated with JWST's specialized wavefront sensing hardware. By combining narrow band and medium band Nyquist-sampled images taken with a science camera we can sense JWST primary mirror segment tip-tilt to lOmas, and piston to a few nm. We can sense inter-segment piston errors of up to 5 coherence lengths of the broadest bandpass filter used ( 250-500 0m depending on the filters). Our approach scales well with an increasing number of segments, which makes it relevant for future segmented-primary space missions.

The EChO Payload is an integrated spectrometer designed to cover the 0.55-16 μm (11 to 16 μm as a goal) wavelength band, subdivided into 5 channels from visible to thermal IR with a common set of optics spectrally dividing the field of view by means of dichroics and a unique electronics interface to the spacecraft, the Data Control Unit (DCU). DCU is mainly a digital unit with processing capabilities based on a rad-hard space qualified processor running the main Application SW (the scientific SW) and some programmable logics. DCU will host the detector’s warm front-end electronics (FEEs) and its main tasks are to implement the payload instruments commanding, the science and housekeeping (HK) data acquisition, conversion and packetisation, the onboard spectra pre-processing, and, finally, to provide finely regulated voltage levels to FEEs. Detector’s proximity cold electronics send analog data and HKs to DCU for digital conversion by sharing a redundant ADC aboard DCU. Analog HKs are previously multiplexed, elaborated and converted to digital format before sending them to the satellite platform, via the SpaceWire (SpW) links. DCU controls the FEEs syncronization (interpreting and routing sync signals and time stamps sent by OBC by means of SpW Time Codes) and runs the main logics to perform all the required tasks and memory management. The EChO DCU electronics basically focuses on the data and command flows, the clock/synchronization and power distribution network and on an overall architecture for a trade-off solution removing or reducing any electronics single-point failure.

The Exoplanet Characterisation Observatory (EChO) is a space mission dedicated to undertaking spectroscopy of transiting exoplanets over the widest wavelength range possible. It is based around a highly stable space platform with a 1.2 m class telescope. The mission is currently being studied by ESA in the context of a medium class mission within the Cosmic Vision programme for launch post 2020. The payload instrument is required to provide simultaneous coverage from the visible to the mid-infrared and must be highly stable and effectively operate as a single instrument. This paper presents the architectural design for the highly interlinked mechanical and thermal aspects of our instrument design. The instrument will be passively cooled to approximately 40K along with the telescope in order to maintain the necessary sensitivity and photometric stability out to mid-infrared wavelengths. Furthermore other temperature stages will be required within the instrument, some of which will implement active temperature control to achieve the necessary thermal stability. We discuss the major design drivers of this complex system such as the need for multiple detector system temperatures of approximately 160K, 40K and 7K all operating within the same instrument. The sizing cases for the cryogenic system will be discussed and the options for providing the cooling of detectors to approximately 7K will be examined. We discuss the trade-offs that we are undertaking to produce a technically feasible payload design which will enable EChO’s exciting science.

EChO, a space mission for exoplanets exploration, is considered the next step for planetary atmospheres characterization. It will be a dedicated observatory to uncover a large selected sample of planets spanning a wide range of masses (from gas giants to super-Earths) and orbital temperatures (from hot to habitable). All targets move around stars of spectral types F, G, K, and M. EChO will provide an unprecedented view of the atmospheres of planets in the solar neighbourhood. The consortium formed by various institutions of different countries is proposing an integrated spectrometer payload for EChO covering the wavelength interval 0.4 to 16 µm. This instrument is subdivided into 4 channels: a visible channel, which includes a fine guidance system (FGS) and a VIS spectrometer, a near infrared channel (SWiR), a middle infrared channel (MWiR), and a long wave infrared module (LWiR). In addition, it contains a common set of optics spectrally dividing the wavelength coverage and injecting the combined light of parent stars and their exoplanets into the different channels. The proposed payload meets all of the key performance requirements detailed in the ESA call for proposals as well as all scientific goals. EChO payload will be based on different spectrometers covering the spectral range mentioned above. Among them, SWiR spectrometer will work from 2.45 microns to 5.45 microns. In this paper, the optical and mechanical designs of the SWiR channel instrument, including the evolution of the different trades followed and the current identification of critical points, are reported on.

The Visible and Near Infrared (VNIR) spectrometer of the EChO will cover the spectral range between 0.55 and 2.50 μm. It has to be designed to assure a high efficiency over whole spectral range. It has to be able to observe stars with an apparent magnitude M_v= 9÷12 and able to see contrasts of the order of 10^-4÷10^-5 in order to measure characteristics of the exoplanets under investigation. VNIR would be a spectrometer in a cross-dispersed configuration by using a combination of a diffraction grating and a prism to spread the light in different wavelengths and in a useful number of orders of diffraction. It will use a Mercury Cadmium Telluride detector to satisfy the requirements of low thermal noise and the EChO system to operate at the working temperature of 40-45K. The instrument will be interfaced to the telescope optics by optical fibers to assure an easier coupling and an easier colocation of the instrument inside the EChO optical bench. The preliminary design of the instrument foresees a resolving power of about 330 with an entrance aperture of 2 arcsec.

The Exoplanet Characterisation Observatory (EChO) is currently being studied by ESA as a medium class mis­ sion to be launched in the third decade of the new millennium. EChO requires exquisite detector sensitivity and stability under low- background conditions. The EChO longest wavelength instrument covers the very long wave­ length (VLWIR) spectral band from 10 to 16 µm and HgCdTe (MCT) photoconductors constitute a promising technology. Currently available MCT detectors have been developed for high-background and high-temperature operations and little is known about the performance achievable when the same detectors are operated at cryo­ genic temperatures, between 77 K and 4 K. Here we report on the optical and dark measurements obtained on VLWIR MCT photoconductors from European manufacturers at cryogenic temperatures.

The EChO satellite provides an opportunity to investigate the magnetic stellar activity and the nature of magnetic interactions of exoplanets with their host stars by using spectropolarimetry from space. These include auroral phenomena induced by the coupling on the exoplanet, induced flows between the planet and parent star, and a broad range of signatures of enhanced magneto-hydrodynamic interactions. A comprehensive view of the structure and evolution of exoplanetary atmospheres requires investigating the escape mechanisms of their constituent species, including the effect of a planetary magnetosphere. Given the distribution of masses and orbital parameters among the currently known gas giant exoplanets, the presence of a significant magnetic field could have some surprising consequences. In analogy with active dynamo-generated fields in close binary star systems, such as the RS CVn stars, a planetary field could link to that of the parent star, producing a strongly dissipative torque and magnetically and tidally locking the planet to its central star. Additionally, the study of stellar magnetism aids understanding of the coronal and chromospheric activity that affects the evolution of the planetary atmospheres.

NISP is the near IR spectrophotometer instrument part of the Cosmic Vision Euclid mission. In this paper we describe an end-to-end simulation scheme developed in the framework of the NISP design study to cover the expected focal-plane on-board pre-processing operations. Non-destructive detector readouts are simulated for a number of different readout strategies, taking into account scientific and calibration observations; resulting frames are passed through a series of steps emulating the foreseen on-board pipeline, then compressed to give the final result. In order to verify final frame quality and resulting computational and memory load, we tested this architecture on a number of hardware platforms similar to those possible for the final NISP computing unit. Here we give the results of the latest tests. This paper mainly reports the technical status at the end of the Definition Phase and it is presented on behalf of the Euclid Consortium.

The Near Infrared Spectrograph and Photometer (NISP) is one of the instruments on board the EUCLID mission. The focal plane array (FPA) consists of 16 HAWAII-2RG HgCdTe detectors from Teledyne Imaging Scientific (TIS), for NIR imaging in three bands (Y, J, H) and slitless spectroscopy in the range 0.9−2µm. Low total noise measurements (i.e. total noise < 8 electrons) are achieved by operating the detectors in multiple non-destructive readout mode for the implementation of both the Fowler and Up-The-Ramp (UTR) sampling, which also enables the detection and removal of cosmic ray events. The large area of the NISP FPA and the limited satellite telemetry available impose to perform the required data processing on board, during the observations. This requires a well optimized on-board data processing pipeline, and high-performance control electronics, suited to cope with the time constraints of the NISP acquisition sequences. This paper describes the architecture of the NISP on-board electronics, which take charge of several tasks, including the driving of each individual HAWAII-2RG detectors through their SIDECAR ASICs, the data processing, inclusive of compression and storage, and the instrument control tasks. We describe the implementation of the processing power needed for the demanding on-board data reduction. We also describe the basic operational modes that will be managed by the system during the mission, along with data flow and the Telemetry/TeleCommands flow. This paper reports the NISP on-board electronics architecture status at the end of the Phase B1, and it is presented on behalf of the Euclid Consortium.

The Command and Data Processing Unit (CDPU) of the Euclid Visible Imager is one of the two warm electronics units of the instrument. It implements on one side the digital interface to the satellite, for telecommands acquisition and telemetry downloading, and on the other side the interface to the focal plane CCDs readout electronics, for science data acquisition and compression. The CDPU main functionalities include the instrument commanding, control and health monitoring. The baseline unit architecture is presented, reporting the results of the phase B1 study and of the trade-off activity carried out to check the performances of the SW implementation of two different lossless compression algorithms on the baseline target processor (LEON3-FT) and on a HW compressor.

In this paper we describe the thermal architecture of the Near Infrared Spectro-Photometer (NISP) on board the Euclid ESA mission. The instrument thermal design is based on the combination of two passive radiators coupled to cold space that, exploiting the beneficial conditions of the L2 thermal environment, provide the temperature references for the main sub-systems. One radiator serves as a 135K heat sink for the opto-mechanical structure and for the front-end cold electronics, while working as an interception stage for the conductive parasitic heat leaks through struts and harness. The second, colder, radiator provides a 95K reference for the instrument detectors. The thermal configuration has to ensure the units optimal operating temperature needed to maximize instrument performance, adopting solutions consistent with the mechanical specifications. At the same time the design has to be compliant with the stringent requirements on thermal stability of the optical and detector units. The periodical perturbation of filter and grism wheel mechanisms together with orbital variations and active loads instabilities make the temperature control one of the most critical issues of the whole design. We report here the general thermal architecture at the end of the Definition Phase, together with the first analysis results and preliminary performance predictions in terms of steady state and transient behavior. This paper is presented on behalf of the Euclid Consortium.

The Near Infrared Spectro-Photometer (NISP) on board the Euclid ESA mission will be developed and tested at various levels of integration using various test equipment which shall be designed and procured through a collaborative and coordinated effort. In this paper we describe the Electrical Ground Support Equipment (EGSE) which shall be required to support the assembly, integration, verification and testing (AIV/AIT) and calibration activities at instrument level before delivery to ESA, and at satellite level, when the NISP instrument is mounted on the spacecraft. We present the EGSE conceptual design as defined in order to be compliant with the AIV/AIT and calibration requirements. The proposed concept is aimed at maximizing the re-use in the EGSE configuration of the Test Equipment developed for subsystem level activities, as well as, at allowing a smooth transition from instrument level to satellite level, and, possibly, at Ground Segment level. This paper mainly reports the technical status at the end of the Definition phase and it is presented on behalf of the Euclid Consortium.

The Hubble Space Telescope is a Ritchie-Chrétien optical design with a main primary concave mirror followed by a convex secondary. The focus is determined by the position of each of these two mirrors. The truss containing them is made of graphite epoxy which has very low thermal expansion. Nevertheless, temperature variations do cause the mirror separation to vary by several microns within an orbit. Additionally, outgassing of water vapor causes a long-term shrinkage which soon after launch in 1990 varied by more than 2 microns per month. This necessitated adjusting the position of the secondary mirror every few months. Currently this rate is greatly reduced and adjustments are needed less than once per year. The focus is monitored monthly to continually assess the need for such adjustments. The measurements have been used to develop models to predict the focus at times between measurements to assist in the analysis of observations. Detailed focus knowledge is of value in photometry, coronagraphy and image deconvolution. The various focus models that have been applied so far are described with an evaluation of their performance. Continuing attempts to refine the model will be discussed.

The Spitzer Space Telescope Infrared Array Camera (IRAC) basic calibrated data reduction pipeline is designed to take a single raw frame from a single IRAC detector and produce a flux-calibrated image that has had all well-understood instrumental signatures removed. We discuss several modifications to the pipeline developed in the last two years in response to the Spitzer warm mission. Due to the different instrument characteristics in the warm mission, we have significantly changed pipeline procedures for masking residual images and mitigating column pulldown. In addition, the muxbleed correction was turned off, because it is not present in the warm data. Parameters relevant to linearity correction, bad pixels, and the photometric calibration have been updated and are continually monitored.

The Infrared Array Camera (IRAC) is now the only science instrument in operation on the Spitzer Space Telescope. The 3.6 and 4.5 µm channels are temperature-stabilized at ~28.7K, and the sensitivity of IRAC is nearly identical to what it was in the cryogenic mission. The instrument point response function (PRF) is a set of values from which one can determine the point spread function (PSF) for a source at any position in the field, and is dependent on the optical characteristics of the telescope and instrument as well as the detector sampling and pixel response. These data are necessary when performing PSF-fitting photometry of sources, for deconvolving an IRAC image, subtracting out a bright source in a field, or for estimating the flux of a source that saturates the detector. Since the telescope and instrument are operating at a higher temperature in the post-cryogenic mission, we re-derive the PRFs for IRAC from measurements obtained after the warm mission temperature set point and detector biases were finalized and compare them to the 3.6 and 4.5 µm PRFs determined during the cryogenic mission to assess any changes.

The fabrication and coating of the mirrors for the James Webb Space Telescope has been completed. The spectral reflectivity of the protected gold coated beryllium mirrors has been measured. The predicted end-of-life transmission through the telescope builds from these values. The additional phenomena that have been analyzed are contamination effects and effects of the environment for the JWST operation about the Earth-Sun L2 Lagrange libration point. The L2 environment analysis has been based on radiation testing of mirror samples and hypervelocity testing to assess the micrometeoroid impact effects. The mirror showed no change in reflectance over the VIS-SWIR wavelengths after exposure to 6-9 Grad (Si) that simulated 6 years orbiting the L2 Lagrange point. The effects of hypervelocity particle impacts on the mirrors from test data has been extrapolated to the to the anticipated flux characteristics for micrometeoroids at the L2 environment. The results show that the micrometeoroid effects are orders of magnitude below the particulate contamination effects. The final end-of-life transmission for the mirrors including all of these phenomena will meet the performance requirements for JWST.

The James Webb Space Telescope (JWST) is a large space based astronomical telescope that will operate at cryogenic temperatures. The architecture has the telescope exposed to space, with a large sun shield providing thermal isolation and protection from direct illumination from the sun. The instruments will have the capability to observe over a spectral range from 0.6 µm to 28 µm wavelengths. The following paper will present updated stray light analysis results characterizing the stray light getting to the instrument focal planes from the full galactic sky, zodiacal background, bright objects near the line of sight, and scattered earth and moon shine. Included is a discussion of internal alignments of pupils at relevant interface planes to stray light. The amount of self-generated infrared background from the Observatory that reaches the instrument focal planes will be presented including the tolerance to the alignment of the edges of the sun shield membranes relative to each other and the telescope.

When the secondary mirror (SM) of a Three-Mirror Anastigmat (TMA) telescope is misaligned with respect to the primary mirror (PM), optical wavefront errors are created. In general, the errors take the form of a dominant coma term, common to all field points, in addition to astigmatism and power terms which vary with field position. The magnitude of the field dependent wavefront is usually only a few percent of that of the common coma term, depending on the size of the field of view being considered. The architecture of the James Webb Space Telescope (JWST), however, presents a unique optical problem in that the common term created by misplacement of the SM is compensated by adjustment of the PM segments. As such, the residual field dependent terms become dominant and can be sensed at multiple field points using phase retrieval techniques. In this paper, we present a linear set of equations that describe the multi-field (MF) wavefront errors resulting from a misaligned SM. It is shown that inverting these equations yields corrections for the SM alignment that can independently control the field-dependent astigmatism and the focal-plane tilt. Computer simulations illustrating the correction are presented.

Experience with the Hubble Space Telescope has shown that accurate models of optical performance are extremely desirable to astronomers, both for assessing feasibility and planning scientific observations, and for data analyses such as point-spread-function (PSF)-fitting photometry and astrometry, deconvolution, and PSF subtraction. Compared to previous space observatories, the temporal variability and active control of the James Webb Space Telescope (JWST) pose a significantly greater challenge for accurate modeling. We describe here some initial steps toward meeting the community's need for such PSF simulations. A software package called WebbPSF now provides the capability for simulating PSFs for JWST's instruments in all imaging modes, including direct imaging, coronagraphy, and non-redundant aperture masking. WebbPSF is intended to provide model PSFs suitable for planning observations and creating mock science data, via a straightforward interface accessible to any astronomer; as such it is complementary to the sophisticated but complex-to-use modeling tools used primarily by optical designers. WebbPSF is implemented using a new exible and extensible optical propagation library in the Python programming language. While the initial version uses static precomputed wavefront simulations, over time this system is evolving to include both spatial and temporal variation in PSFs, building on existing modeling efforts within the JWST program. Our long-term goal is to provide a general-purpose PSF modeling capability akin to Hubble's Tiny Tim software, and of sufficient accuracy to be useful to the community.

The Near Infrared Spectrograph (NIRSpec) is one of four science instruments aboard the James Webb Space Telescope (JWST) scheduled for launch in 2018. NIRSpec is sensitive in the wavelength range from ~0.6 to 5.0 micron and will be capable of obtaining spectra from more than a 100 objects simultaneously by means of a programmable micro shutter array. It will also provide an integral eld unit for 3D spectroscopy and xed slits for high contrast spectroscopy of individual sources and planet transit observations. We present results obtained during the rst cryogenic instrument testing in early 2011, demonstrating the excellent optical performance of the instrument. We also describe the planning of NIRSpecs forthcoming second calibration campaign scheduled for early 2013.

NIRSpec is the main near-infrared spectrograph on board the James Webb Space Telescope, offering multi-object capabilities as well as an integral field unit and a number of fixed slits for studies of individual objects. In this paper, we describe the unique challenges in calibrating this complex instrument, and the approach taken to deal with them, both in terms of operational procedures and via automated processing of NIRSpec data. We provide a high-level description of the sequence of processing steps required for NIRSpec science data, and the necessary on-ground calibration files. We focus our discussion on the case of a typical multi-object observation with the MSA, in which adjacent micro-shutters are used to sample the science object and the sky background in an alternating way. This dithering strategy is particularly well suited for faint targets, but its guiding principles also apply to other NIRSpec modes.

We present a detailed analysis of measurements collected during the first ground-based cryogenic calibration campaign of NIRSpec, the Near-Infrared Spectrograph for the James Webb Space Telescope (JWST). In this paper we concentrate on the performances of the NIRSpec grating wheel, showing that the magneto-resistive position sensors installed on the wheel provide very accurate information on the position of the wheel itself, thereby enabling an efficient acquisition of the science targets and a very accurate extraction and calibration of their spectra.

The James Webb Space Telescope is a large deployable cryogenic space telescope that is pointed on the sky by control of the attitude of the integrated spacecraft and telescope. The primary mirror has 18 hexagonal Primary Mirror Segment Assemblies (PMSA) that are deployed; 3 on each of two deployable wings, and 12 on a fixed central section of the Primary Mirror Backplane Support Structure. The Secondary Mirror (SM) is deployed from the Secondary Support Structure that folds out from the backplane, and the complete Telescope and Integrated Science Instrument Module are deployed in extension from the spacecraft. The resulting tolerances will result in a "first light" image that has a spread array of 18 individual images for each point source located within the field of view. The initial attitude of the spacecraft will be adjusted to point the telescope to a desired star field for the initial WFSC commissioning process. The deployment tolerances will result in the telescope field of view being offset from the desired location. By use of a sequence of pointings, a mosaic "first light" image that includes the multiplicity of the 18 misaligned segment images may be created that will allow the calibration of the offset between the telescope boresight and the spacecraft attitude control system, allowing subsequent pointing to be done accurately to a fraction of the field of view of the instruments using spacecraft attitude control.

During cryogenic vacuum testing of the James Webb Space Telescope (JWST) Integrated Science Instrument Module (ISIM), the global alignment of the ISIM with respect to the designed interface of the JWST optical telescope element (OTE) will be measured through a series of optical characterization tests. These tests will determine the locations and orientations of the JWST science instrument projected focal surfaces and entrance pupils with respect to their corresponding OTE optical interfaces. Thermal, finite element and optical modeling will then be used to predict the on-orbit optical performance of the observatory. If any optical performance non-compliances are identified, the ISIM will be adjusted to improve its performance. If this becomes necessary, ISIM has a variety of adjustments that can be made. The lengths of the six kinematic mount struts that attach the ISIM to the OTE can be modified and five science instrument focus positions and two pupil positions can be individually adjusted as well. In order to understand how to manipulate the ISIM’s degrees of freedom properly and to prepare for the ISIM flight model testing, we have completed a series of optical-mechanical analyses to develop and identify the best approaches for bringing a non-compliant ISIM Element back into compliance. During this work several unknown misalignment scenarios were produced and the simulated optical performance metrics were input into various mathematical modeling and optimization tools to determine how the ISIM degrees of freedom should be adjusted to provide the best overall optical performance.

The light-weighted design of the Optical Telescope Element (OTE) of the James Webb Telescope (JWST) leads to additional sensitivity to vibration from the ground – an important consideration to the measurement uncertainty of the wavefront error (WFE) in the primary mirror. Furthermore, segmentation of the primary mirror leads to rigid-body movements of segment areas in the WFE. The ground vibrations are minimized with modifications to the test facility, and by the architecture of the equipment supporting the load. Additional special test equipment (including strategically placed isolators, tunable mass dampers, and cryogenic magnetic dampers) mitigates the vibration and the response sensitivity before reaching the telescope. A multi-wavelength interferometer is designed and operated to accommodate the predicted residual vibration. Thermal drift also adds to the measurement variation. Test results of test equipment components, measurement theory, and finite element analysis combine to predict the test uncertainty in the future measurement of the primary mirror. The vibration input to the finite element model comes from accelerometer measurements of the facility with the environmental control pumps operating. One of the isolators have been built and tested to validate the dynamic performance. A preliminary model of the load support equipment and the OTE with the Integrated Science Instrument Module (ISIM) is complete. The performance of the add-on dampers have been established in previous applications. And operation of the multi-wavelength interferometer was demonstrated on a scaled hardware version of the JWST in an environment with vibration and thermal drift.

The flight model Fine Guidance Sensor (FGS) on the James Webb Space Telescope (JWST) has successfully completed its performance verification tests. The FGS cryogenic test is described along with some of the key guider performance results which have been obtained. In particular we describe the noise equivalent angle (NEA) performance as a function of guide star magnitude for the guider tracking mode. Tracking mode must be able to follow a guide star moving across the field of view of either guider, primarily to allow the Observatory line of sight to settle in advance of the fine guidance mode. FGS tracking mode will also be used for JWST’s moving target observing mode. The track testing made use of the two movable sources within our JWST telescope simulator. The NEA of the FGS-Guiders will in part determine the ultimate image quality of the JWST Observatory.

The Fine Guidance Sensor (FGS) on the James Webb Space Telescope (JWST) has a science observing capability that was to be provided by a tunable Fabry-Pérot etalon incorporating dielectric coated etalon plates with a small vacuum gap and piezoelectric actuators (PZTs). The JWST etalon was more challenging than our existing ground-based operational systems due to the low-order gap, the extremely wide waveband and the environmental specifications. Difficulties were encountered in providing the required performance due to variability in the mechanical gap after exposure to the vibration, shock and cryogenic cycling environments required for the JWST mission. The risks associated with operating the flight model etalon in the space environment, along with changes in scientific priorities, resulted in the etalon being replaced by the grism-based Near-Infrared Imager and Slitless Spectrograph (NIRISS). We describe here the performance of the etalon system and the unresolved risks that contributed to the decision to change the flight instrument.

The FPC (Fine-guiding and astroPhysics Camera) consists of two NIR (Near Infrared) cameras as focal plane instruments of the SPICA (Space Infrared Telescope for Cosmology and Astrophysics). The FPC-G (FPC-Guidance) is for fine guiding with an accuracy of less than 0.036" at 0.5 Hz, and the FPC-S (FPC-Science) is for a back-up of the FPC-G as well as for scientific observations with 10 filters - including 3 LVFs (Linear Variable Filter) - in NIR (0.8 - 5.2µm) imaging and spectroscopy. As one of the international consortium member of the SPICA project, KASI (Korea Astronomy and Space science Institute) is leading the conceptual design and the scientific cases of the FPC with Korea/Japan participants.

We describe the principles and potential of Color-Differential Astrometry (CDA), a high-resolution technique easily implementable on the Science Coronographic Instrument (SCI) of the SPICA satellite, and aimed here at the direct detection and spectroscopy of giant Extrasolar Planets (ESP). By measuring the photocentre of the source diffraction pattern relatively between dispersed spectral channels, CDA gives access to flux ratio and angular information well beyond the telescope resolution limit. Applied to known ESPs, it can yield the inclination (thus the mass) and spectrum of the planet. Our estimates show that low-resolution spectroscopy of Jupiter-radius ESP can be measured within a few hours for planets at orbital distances ranging from 0.05 AU to a few AUs, thus complementing the detection range expected using the coronographic measurements. More generally, it may also apply to any unresolved source with some wavelength-dependent asymmetry. In addition to the ESP cases considered for the scientific signal and to their associated fundamental noises, we also present the instrumental effects and a dedicated optical testbench. The combined effects of several instrumental noise sources can be introduced into our numerical model (pointing errors, beam tip-tilt, optical aberations, variations of the detector gain table), and then confronted to measurements from the experimental testbench.

TNO, together with its partners, have designed a cryogenic scanning mechanism for use in the SAFARI¹ Fourier Transform Spectrometer (FTS) on board of the SPICA mission. SPICA is one of the M-class missions competing to be launched in ESA's Cosmic Vision Programme² in 2022. JAXA³ leads the development of the SPICA satellite and SRON is the prime investigator of the Safari instrument. The FTS scanning mechanism (FTSM) has to meet a 35 mm stroke requirement with an Optical Path Difference resolution of less then 15 nm and must fit in a small volume. It consists of two back-to-back roof-top mirrors mounted on a small carriage, which is moved using a magnetic bearing linear guiding system in combination with a magnetic linear motor serving as the OPD actuator. The FTSM will be used at cryogenic temperatures of 4 Kelvin inducing challenging requirements on the thermal power dissipation and heat leak. The magnetic bearing enables movements over a scanning stroke of 35.5 mm in a small volume. It supports the optics in a free-floating way with no friction, or other non-linearities, with sub-nanometer accuracy. This solution is based on the design of the breadboard ODL (Optical Delay Line) developed for the ESA Darwin mission⁴ and the MABE mechanism developed by Micromega Dynamics. During the last couple of years the initial design of the SAFARI instrument, as described in an earlier SPIE 2010 paper⁵, was adapted by the SAFARI team in an evolutionary way to meet the changing requirements of the SPICA payload module. This presentation will focus on the evolution of the FTSM to meet these changing requirements. This work is supported by the Netherlands Space Office (NSO).

Mid-infrared Medium Resolution Spectrometer (MRS) is one of the key spectroscopic modules of Mid- Infrared Camera and Spectrometers (MCS) that will be onboard SPICA. MRS is an Echelle Grating spectrometer designed to observe a number of fine structure lines of ions and atoms, molecular lines, and band features stemming from solid particles and dust grains of the interstellar and circumstellar medium in the mid-infrared wavelength range. MRS consists of two channels; the shorter wavelength channel (MRS-S) covers the spectral range from 12.2 to 23.0 micron with a spectral resolution power of R~1900-3000 and the longer wavelength channel (MRS-L) covers from 23.0 to 37.5 micron with R~1100-1500 on the basis of the latest results of the optical design. The distinctive functions of the MRS are (1) a dichroic beam splitter equipped in the fore-optics, by which the same field of view is shared between the two channels, and (2) the small format image slicer as the integral field unit installed in each channel. These functions enable us to collect continuous 12-38 micron spectra of both the point-like and diffuse sources reliably with a single exposure pointed observation. In this paper, the specifications and the expected performance of the MRS are summarized on the basis of the latest results of the optical design. The latest progress in the development of the key technological elements, such as the Dichroic Beam Splitter and the Small Format Monolithic Slice Mirrors, are also reported.

SPICA (Space Infrared Telescope for Cosmology and Astrophysics) is a Japan-led infrared astronomical satellite project with a 3.2-m lightweight cryogenic telescope. The SPICA telescope has stringent requirements such as that for the imaging performance to be diffraction-limited at the shortest core wavelength of 5 microns at the operating temperature of 6 K. The design of the telescope system has been studied by the Europe-Japan telescope working group led by ESA with the European industries, the results of which will be presented in other papers. We here present our recent optical testing activities in Japan for the SPICA telescope, focusing on the experimental and numerical studies of stitching interferometry. The full pupil of the SPICA telescope will be covered by a sub-pupil array consisting of small autocollimating flat mirrors (ACFs), which are rotated with respect to the optical axis of the telescope. For preliminary stitching experiments, we have fabricated an 800-mm lightweight telescope all made of the C/SiC called HBCesic, which is a candidate mirror material for the SPICA telescope, and started optical testing with 900-mm and 300-mm ACFs at an ambient temperature. ACFs can suffer significant surface deformation in testing a telescope at cryogenic temperatures, which is difficult to be measured directly. We therefore investigate the effects of the surface figure errors of the ACFs on stitching results by numerical simulation.

The Space Infrared Telescope for Cosmology and Astrophysics (SPICA) is a 3.2m cooled (below 6K) telescope mission which covers mid- and far-IR waveband with unprecedented sensitivity. An overview of recent design updates of the Scientific Instrument Assembly (SIA), composed of the telescope assembly and the instrument optical bench equipped with Focal Plane Instruments (FPIs) are presented. The FPI international science and engineering review is on-going to determine the FPI suite onboard SPICA: at present the mandatory instruments and functions to perform the unique science objectives of the SPICA mission are now consolidated. The final decision on the composition of the FPI suite is expected in early 2013. Through the activities in the current pre-project phase, several key technical issues which impact directly on the instruments’ performances and the science requirements and the observing efficiency have been identified, and extensive works are underway both at instrument and spacecraft level to resolve these issues and to enable the confirmation of the SPICA FPI suite.

Mid-infrared Camera and Spectrometer (MCS) is one of focal plane instruments for SPICA (Space Infrared Telescope for Cosmology and Astrophysics), which have 3 m class 6 K cooled telescope. MCS will provide wide field imaging and low-, medium-, and high-resolution spectroscopic observing capabilities with 7 detectors in the wavelength range from 5 to 38 micron. Large format array detectors are required in order to realize wide field of view in imaging and wide spectral coverage in spectroscopy. We are planning to cover the wavelength range of 5-26 micron by Si:As IBC 2K x 2K and 20-38 micron by Si:Sb BIB 1K x 1K. The development status and their design including the electrical and thermal design are described.

We present the preliminary design of the Instrument Control Unit (ICU) of the SpicA FAR infrared Instrument (SAFARI), an imaging Fourier Transform Spectrometer (FTS) designed to give continuous wavelength coverage in both photometric and spectroscopic modes from around 34 to 210 µm. Due to the stringent requirements in terms of mass and volume, the overall SAFARI warm electronics will be composed by only two main units: Detector Control Unit and ICU. ICU is therefore a macro-unit incorporating the four digital sub-units dedicated to the control of the overall instrument functionalities: the Cooler Control Unit, the Mechanism Control Unit, the Digital processing Unit and the Power Supply Unit. Both the mechanical solution adopted to host the four sub-units and the internal electrical architecture are presented as well as the adopted redundancy approach.

This paper presents a conceptual design for a spectrometer designed specifically for characterizing transiting exoplanets with space-borne infrared telescopes. The design adopting cross-dispersion is intended to be simple, compact, highly stable, and has capability of simultaneous coverage over a wide wavelength region with high throughput. Typical wavelength coverage and spectral resolving power is 1-13µm with a spectral resolving power of ~ a few hundred, respectively. The baseline design consists of two detectors, two prisms with a dichroic coating and microstructured grating surfaces, and three mirrors. Moving parts are not adopted. The effect of defocusing is evaluated for the case of a simple shift of the detector, and anisotropic defocusing to maintain the spectral resolving power. Variations in the design and its application to planned missions are also discussed.

FINESSE (Fast INfrared Exoplanet Spectroscopic Survey Explorer) will provide uniquely detailed information on the growing number of newly discovered planets by characterizing their atmospheric composition and temperature structure. This NASA Explorer mission, selected for a competitive Phase A study, is unique in its breath and scope thanks to broad instantaneous spectroscopy from the optical to the mid-IR (0.7 – 5 micron), with a survey of exoplanets measured in a consistent, uniform way. For 200 transiting exoplanets ranging from Terrestrial to Jovians, FINESSE will measure the chemical composition and temperature structure of their atmospheres and trace changes over time with exoplanet longitude. The mission will do so by measuring the spectroscopic time series for a primary and secondary eclipse over the exoplanet orbital phase curve. With spectrophotometric precision being a key enabling aspect for combined light exoplanet characterization, FINESSE is designed to produce spectrophotometric precision of better than 100 parts-per-million per spectral channel without the need for decorrelation. The exceptional stability of FINESSE will even allow the mission to characterize non-transiting planets, potentially as part of FINESSE’s Participating Scientist Program. In this paper, we discuss the flow down from the target availability to observations and scheduling to the analysis and calibration of the data and how it enables FINESSE to be the mission that will truly expand the new field of comparative exoplanetology.

Gaia is an ESA mission which will measure the positions, distances, space motions, and many physical characteristics for one billion stars in our Galaxy and beyond. The satellite will have three instruments on board: the Astrometric Field for the astrometry; the Blue and Red Photometers for the low-resolution spectroscopy and the Radial Velocity Spectrometer which will allow measuring radial velocities. This paper will give an overview of the processing of the dispersed images for BP and RP: the data will be corrected for CCD related effects in the pre-processing, where also the sky background and the flux contamination from neighbouring sources will be removed; the data will be then internally calibrated to the same "mean instrument" and externally calibrated to obtain spectrum and flux in physical units, which will be stored in the final catalogue.

Detection of earth-size exoplanets using the astrometric signal of the host star requires sub microarcsecond measurement precision. One major challenge in achieving this precision using a medium-size (<2-m) space telescope is the calibration of dynamic distortions. The researchers propose a diffractive pupil technique that uses an array of approximately 5um dots on the primary mirror that generate polychromatic diffraction spikes in the focal plane. The diffraction spikes encode optical distortions in the optical system and may be used to calibrate astrometric measurements. This concept can be used simultaneously with coronagraphy for exhaustive characterization of exoplanets (mass, spectra, orbit). At the University of Arizona, a high precision astrometry laboratory was developed to demonstrate the capabilities of this diffractive pupil concept. The researchers aim to demonstrate that the diffractive pupil can improve current limiting factors of astrometric accuracy. This paper describes this laboratory and the results showing that this technique can effectively calibrate dynamic distortions.

We have investigated the on-orbit properties of the spectroscopic data taken with NIR channel of the Infrared Camera (IRC) onboard AKARI during the phases 1, 2 and 3. We have determined the boundary shape of the aperture mask of NIR channel by using the spectroscopic data of uniform zodiacal background emission. The information on the aperture mask shape is indispensable in modeling and subtracting the spectroscopic background patterns made by the diffuse background emission such as zodiacal emission and the Galactic cirrus emission. We also have examined the wavelength dependency on the profile of the point spread function and its effect on the spectroscopic data. The obtained information is useful, for example, in reducing the spectroscopic data of a point source badly affected by bad pixels and in decomposing the overlapping spectra of sources that are aligned in the dispersion direction with a small offset the cross dispersion direction. In this paper, we summarize the supplementary knowledge that will be useful for the advanced data reduction procedures of NIR spectroscopic datasets.

The Herschel SPIRE On-Board Software (OBS) is presented. This real time operational software controls the scientific data transmission and keeps a control layer between the SPIRE Mission Timeline (MTL) and the real instruments status. It embeds a multithreaded engine that interprets control procedures for the detector and mechanism subsystems. An autonomous monitoring agent keeps control of subsystems status, and takes local decisions based on pre-loaded reaction maps. The behaviour of low level system functions is configurable remotely via the reactions maps and control procedures.

Establishing improved spectrophotometric standards is important for a broad range of missions and is relevant to many astrophysical problems. ACCESS, “Absolute Color Calibration Experiment for Standard Stars”, is a series of rocket-borne sub-orbital missions and ground-based experiments designed to enable improvements in the precision of the astrophysical flux scale through the transfer of absolute laboratory detector standards from the National Institute of Standards and Technology (NIST) to a network of stellar standards with a calibration accuracy of 1% and a spectral resolving power of 500 across the 0.35-1.7µm bandpass.

Nano-JASMINE (NJ) is a very small astrometry satellite project led by the National Astronomical Observatory of Japan. The satellite is ready for launch, and the launch is currently scheduled for late 2013 or early 2014. The satellite is equipped with a fully depleted CCD and is expected to perform astrometry observations for stars brighter than 9 mag in the zw-band (0.6 µm–1.0 µm). Distances of stars located within 100 pc of the Sun can be determined by using annual parallax measurements. The targeted accuracy for the position determination of stars brighter than 7.5 mag is 3 mas, which is equivalent to measuring the positions of stars with an accuracy of less than one five-hundredth of the CCD pixel size. The position measurements of stars are performed by centroiding the stellar images taken by the CCD that operates in the time and delay integration mode. The degradation of charge transfer performance due to cosmic radiation damage in orbit is proved experimentally. A method is then required to compensate for the effects of performance degradation. One of the most effective ways of achieving this is to simulate observed stellar outputs, including the effect of CCD degradation, and then formulate our centroiding algorithm and evaluate the accuracies of the measurements. We report here the planned procedure to simulate the outputs of the NJ observations. We also developed a CCD performance-measuring system and present preliminary results obtained using the system.

Because of its nicely chromatic behavior, Calcium Fluoride (CaF₂) is a nice choice for an optical designer as it can easily solve a number of issues, giving the right extra degree of freedom in the optical design tuning. However, switching from tablet screens to real life, the scarcity of information -and sometimes the bad reputation in term of fragility- about this material makes an overall test much more than a "display determination" experiment. We describe the extensive tests performed in ambient temperature and in thermo-vacuum of a prototype, consistent with flight CTEs, of a 200mm class camera envisaged for the PLATO (PLAnetary Transit and Oscillations of Stars) mission. We show how the CaF₂ lens uneventfully succeeded to all the tests and handling procedures, and discuss the main results of the very intensive test campaign of the PLATO Telescope Optical Unit prototype.

A notional space telescope configuration is presented that addresses issues of angular resolution, spectral bandwidth and rejection of host star glare by means of a double dispersion architecture. The telescope resolves angle by wavelength. In an earlier embodiment for surveys, a primary objective grating telescope architecture was shown to acquire millions of objects in one observation cycle, one wave length at a time. The proposed HPF can detect exquisite spectral signatures out of millions of wavelengths in albedos - one exoplanetary system at a time. Like its predecessor, the new HPF telescope has a ribbon-shaped flat gossamer membrane primary objective that lends itself to space deployment, but the preferred embodiment uses a holographic optical element rather than a plane grating. The HOE provides an improvement in efficiency at select wavelength bands. The considerable length of the membrane can be in the 100 meter class providing angular resolution sufficient to resolve planets in the habitable zone and also spectral resolution sufficient to earmark habitability. A novel interferometric secondary spectrograph rejects host star glare. However, the architecture cannot disambiguate multiple stellar sources and may require unprecedented focal lengths in the primary objective to isolate one system at a time.

Here we present a novel diffraction limited spectrograph (NanoSpec) designed for integration in the 0.75kg i-INPSIRE satellite at the University of Sydney. NanoSpec is a single-mode fibre fed spectrograph operating very close to the diffraction limit over a wavelength range of 450nm to 700nm. The spectrograph is fed light via a single-mode (and thus diffraction limited) fibre pseudo-slit, allowing an extremely compact spectrograph while maintaining high performance. The current design has two configurations (for two different detectors), both achieving diffraction limited resolving powers (λ/Δλ) of 650 and 1400 respectively. The primary goal of NanoSpec is to demonstrate the potential of the PIMMS (photonic integrated multimode micro-spectrograph) type design for deployment in high altitude and space-based applications. To that end we present the optical design and laboratory based testing in preparation for a high altitude balloon launch and later on the i-INPSIRE satellite.

We present an overview of the current status of the space mission Millimetron. Millimetron is a large 10-m cooled space telescope optimized for operation in the submillimeter and far infrared wavelengths. This mission will be able to contribute to the solution of several key problems in astrophysics, such as study of the formation and evolution of stars and planets, galaxies, quasars and many others. The telescope will have an unprecedented sensitivity in the single-dish observation mode and an extremely high spatial resolution as an element of a ground-space very long baseline interferometry (VLBI) system. The mission will have a cryogenic instruments and antenna, which will be cooled passively with radiation shields and actively with mechanical coolers. With this cooling combination the 10-m space telescope may reach a temperature of about 4.5 K. The Millimetron is proposed as a Russian-led mission with an extensive international consortium in various countries. The mission launch is planned for 2017.

The ORIGIN concept is a space mission with a gamma ray, an X-ray and an optical telescope to observe the gamma ray bursts at large Z to determine the composition and density of the intergalactic matter in the line of sight. It was an answer to the ESA M3 call for proposal. The optical telescope is a 0.7-m F/1 with a very small instrument box containing 3 instruments: a slitless spectrograph with a resolution of 20, a multi-imager giving images of a field in 4 bands simultaneously, and a cross-dispersed Échelle spectrograph giving a resolution of 1000. The wavelength range is 0.5 μm to 1.7 μm. All instruments fit together in a box of 80 mm x 80 mm x 200 mm. The low resolution spectrograph uses a very compact design including a special triplet. It contains only spherical surfaces except for one tilted cylindrical surface to disperse the light. To reduce the need for a high precision pointing, an Advanced Image Slicer was added in front of the high resolution spectrograph. This spectrograph uses a simple design with only one mirror for the collimator and another for the camera. The Imager contains dichroics to separate the bandwidths and glass thicknesses to compensate the differences in path length. All 3 instruments use the same 2k x 2k detector simultaneously so that telescope pointing and tip-tilt control of a fold mirror permit to place the gamma ray burst on the desired instrument without any other mechanism.

The goal of the CubeSat Deformable Mirror Demonstration (DeMi) is to characterize the performance of a small deformable mirror over a year in low-Earth orbit. Small form factor deformable mirrors are a key technology needed to correct optical system aberrations in high contrast, high dynamic range space telescope applications such as space-based coronagraphic direct imaging of exoplanets. They can also improve distortions and reduce bit error rates for space-based laser communication systems. While follow-on missions can take advantage of this general 3U CubeSat platform to test the on-orbit performance of several different types of deformable mirrors, this first design accommodates a 32-actuator Boston Micromachines MEMS deformable mirror.

Several small space coronagraphs have been proposed to characterize cold exoplanets in reflected light. Studies have mainly focused on technical feasibility because of the huge star/planet flux ratio to achieve in the close-in stellar environment (10⁸-10¹⁰ at 0.2"). However, the main interest of such instruments, the analysis of planet properties, has remained highly unexplored so far. We performed numerical simulations to assess the ability of a small space coronagraph to retrieve spectra of mature Jupiters, Neptunes and super-Earths under realistic assumptions. We describe our assumptions: exoplanetary atmosphere models, instrument numerical simulation and observing conditions. Then, we define a criterion and use it to determine the required exposure times to measure several planet parameters from their spectra (separation, metallicity, cloud and surface coverages) for particular cases. Finally, we attempt to define a parameter space of the potential targets. In the case of a solar-type star, we show that a small coronagraph can characterize the spectral properties of a 2-AU Jupiter up to 10 pc and the cloud and surface coverage of super-Earths in the habitable zone for a few stars within 4-5 pc. Potentially, SPICES could perform analysis of a hypothetical Earth-size planet around α Cen A and B.

The use of an external occulter, or starshade, has been proposed as one method for the direct detection and spectral characterization of terrestrial planets around other stars, a key goal identified in ASTRO2010. Because of the observational geometry, one of the concerns is stray light from the edge of the starshade that is scattered into the line of sight of the telescope. We have developed a stray light model using physical properties of a realizable starshade edge geometry and material to calculate the resulting stray light. The background signal due to stray light has been calculated for the two telescope architectures adopted for study by the Exoplanet Exploration Program Analysis Group (ExoPAG), a 4 m monolithic and an 8 m segmented mirror design. Using these results, we have developed a set of design requirements and structure features that will result in a buildable system with stray light levels that meet the overall system sensitivity requirements.

The Multi Element Telescope for Imaging and Spectroscopy (METIS) is the coronagraph selected for the Solar Orbiter payload, adopted in October 2011 by ESA for the following Implementation Phase. The instrument design has been conceived by a team composed by several research institutes with the aim to perform both VIS and EUV narrow-band imaging and spectroscopy of the solar corona. METIS, owing to its multi-wavelength capability, will address some of the major open issues in understanding the physical processes in the corona and the solar wind origin and properties, exploiting the unique opportunities offered by the SO mission profile. The METIS Processing and Power Unit (MPPU) is the Instrument's power supply and on-board data handling modular electronics, designed to address all the scientific requirements of the METIS Coronagraph. MPPU manages data and command flows, the timing and power distribution networks and its architecture reflects several trade-off solutions with respect to the allocated resources in order to reduce any possible electronics single-point failure. This paper reports on the selected HW and SW architectures adopted after the Preliminary Design Review (PDR), performed by ESA in early 2012.

The Near Earth Object Surveillance Satellite (NEOSSat) is a small satellite dedicated to finding near Earth asteroids. Its surveying strategy consists of imaging areas of the sky to low solar elongation, while in a sun synchronous polar orbit (dawn-dusk). A high performance baffle will control stray light mainly due to Earth shine. Observation scenarios require solar shielding down to 45 degree solar elongation over a wide range of ecliptic latitudes. In order to detect the faintest objects (approx 20^th v mag) given a 15 cm telescope and CCD detection system, background from stray light is a critical operational concern. The required attenuation is in the order of 10^-12. The requirement was verified by analyses; testing was not attempted because the level of attenuation is difficult to measure reliably. We report consistent results of stray light optical modelling from two independent analyses. Launch is expected for late 2012.

Rosetta is a cornerstone mission of the European Space Agency (ESA); it has been launched in March 2004 and it will reach its primary target, the 67P/Churyumov Gerasimenko comet, in 2014. One of the Rosetta instruments is the OSIRIS camera system; it is composed of a Wide Angle Camera (WAC) and a Narrow Angle Camera (NAC). The NAC will observe at high resolution regions on the comet surface, while the WAC, 12°x12° Field of View (FoV), has been mainly designed for observing the weak coma features surrounding the bright comet nucleus. Being the expected contrast between the gas and dust jets radiance and the nucleus one of the order of 1/1000, a high contrast capability is required for the WAC camera. To meet this requirement, its optical design is off-axis and unobstructed, and to deeply study gas and dust emissions, the camera is equipped with 14 filters, each with its proper wavelength selection characteristics, in the range 230-720 nm. The theoretical achievable contrast capability is limited by multiple ghost images generated by the optical elements in the focal plane assembly, in fact the incoming beam is partially reflected on the surfaces of the filters, on the detector radiation protective glass cover and on the CCD detector itself. Given that the knowledge of ghosts position and intensity is essential for an adequate scientific data reduction, in this paper an analysis of the ghosts, the solutions adopted to limit image degradation and the impact on the WAC imaging performance are presented.

A new solar flare spectral component has been found with intensities increasing for larger sub-THz frequencies, spectrally separated from the well known microwaves component, bringing challenging constraints for interpretation. Higher THz frequencies observations are needed to understand the nature of the mechanisms occurring in flares. A twofrequency THz photometer system was developed to observe outside the terrestrial atmosphere on stratospheric balloons or satellites, or at exceptionally transparent ground stations. 76 mm diameter telescopes were designed to observe the whole solar disk detecting small relative changes in input temperature caused by flares at localized positions at 3 and 7 THz. Golay cell detectors are preceded by low-pass filters to suppress visible and near IR radiation, band-pass filters, and choppers. It can detect temperature variations smaller than 1 K with time resolution of a fraction of a second, corresponding to small burst intensities. The telescopes are being assembled in a thermal controlled box to which a data conditioning and acquisition unit is coupled. While all observations are stored on board, a telemetry system will forward solar activity compact data to the ground station. The experiment is planned to fly on board of long-duration stratospheric balloon flights some time in 2013-2015. One will be coupled to the GRIPS gamma-ray experiment in cooperation with University of California, Berkeley, USA. One engineering flight will be flown in the USA, and a 2 weeks flight is planned over Antarctica in southern hemisphere summer. Another long duration stratospheric balloon flight over Russia (one week) is planned in cooperation with the Lebedev Physics Institute, Moscow, in northern hemisphere summer.

Echoes is a project of a space-borne instrument which has been proposed as part of the JUICE mission which is selected in the Cosmic Vision program of the European Space Agency (ESA) to perform seismic and dynamics studies of Jupiter's interior and atmosphere. Based on an original Mach-Zehnder design, the instrument aims to measure Doppler shifts of solar spectral lines, which are reflected by cloud layers of Jupiter's upper troposphere, coupled with imaging capabilities. It is specified to detect global oscillations with degree up to l = 50 and amplitude as low as 1 cm/s at the surface of Jupiter. In order to check the compliance of the instrument, and its capability to operate in representative environment (TRL5), we build a prototype to perform tests. In this paper, we present the prototype implemented at Observatoire de la Côte d'Azur in collaboration with Institut d'Astrophysique Spatiale. We describe the design of the Mach-Zehnder and the procedure of control and adjustment. We present the necessary tests and we show on simulation that the measurements will provide the required precision. In conclusion, we will explain the perspective for such a new instrument.

METIS, the multi element telescope for imaging and spectroscopy, is a solar coronagraph foreseen for the Solar Orbiter mission. METIS is conceived to observe the solar corona from a near-sun orbit in three different spectral bands: in the HeII EUV narrow band at 30.4 nm, in the HI UV narrow band at 121.6 nm, and in the visible light band (500 - 650 nm). The visible light from the corona is ten million times fainter than the light emitted by the solar disk, so a very stringent light suppression design is needed for the visible channel. METIS adopts an “inverted occulted” configuration, where the disk light is shielded by an annular shape occulter, after which an annular aspherical mirror M1 collects the signal coming from the corona. The disk light heading through M1 is back-rejected by a suitable spherical mirror M0. This paper presents the stray light analysis for this new-concept configuration, performed with a ray tracing simulation, to insure the opto-mechanical design grants a stray light level below the limit of 10^-9 times the coronal signal intensity. A model of the optics and of the mechanical parts of the telescope has been realized with ASAP (Breault Research TM); by means of a Montecarlo ray tracing, the effect of stray light on VIS and UVEUV channels has been simulated.

We report on the feasibility study of a mid-infrared (8-18 µm) spectro-imager called THERMAP, based on an uncooled micro-bolometer detector array. Due to the recent technological development of these detectors, which have undergone significant improvements in the last decade, we wanted to test their performances for the Marco Polo R ESA Cosmic Vision mission. In this study, we demonstrate that the new generation of uncooled micro-bolometer detectors has all the imaging and spectroscopic capabilities to fulfill the scientific objectives of this mission. In order to test the imaging capabilities of the detector, we set up an experiment based on a 640x480 ULIS micro-bolometer array, a germanium objective and a black body. Using the results of this experiment, we show that calibrated radiometric images can be obtained down to at least 255 K (lower limit of our experiment), and that two calibration points are sufficient to determine the absolute scene temperature with an accuracy better than 1.5 K. Adding flux attenuating neutral density mid-infrared filters (transmittance: 50%, 10%, 1%) to our experiment, we were able to evaluate the spectroscopic performances of the detector. Our results show that we can perform spectroscopic measurements in the wavelength range 8-16 µm with a spectral resolution of R~40-80 for a scene temperature <300 K, the typical surface temperature of a Near Earth Asteroid at 1 AU from the Sun. The mid-infrared spectro-imager THERMAP, based on the above detector, is therefore well suited for the Marco Polo R mission.

The Photospheric and Helioseismic imager (PHI) on board of the ESA mission Solar Orbiter, to be launched in 2017, will provide measurements with high polarimetric accuracy of the photospheric solar magnetic field at high solar latitudes. The needed pointing precision requires an image stabilisation (ISS) to compensate for spacecraft jitter. The image stabilisation system works as a correlation tracker with a high-speed camera and a fast steerable mirror. The optomechanical and electronic design of the system will be presented.

We review the design, fabrication, performance, and future prospects for a complex apodized Lyot coronagraph for highcontrast exoplanet imaging and spectroscopy. We present a newly designed circular focal plane mask with an inner working angle of 2.5 λ/D. Thickness-profiled metallic and dielectric films superimposed on a glass substrate provide control over both the real and imaginary parts of the coronagraph wavefront. Together with a deformable mirror for control of wavefront phase, the complex Lyot coronagraph potentially exceeds billion-to-one contrast over dark fields extending to within angular separations of 2.5 λ/D from the central star, over spectral bandwidths of 20% or more, and with throughput efficiencies better than 50%. Our approach is demonstrated with a linear occulting mask, for which we report our best laboratory imaging contrast achieved to date. Raw image contrasts of 3×10^-10 over 2% bandwidths, 6×10^-10 over 10% bandwidths, and 2×10^-9 over 20% bandwidths are consistently achieved across high contrast fields extending from an inner working angle of 3 λ/D to a radius of 15 λ/D. Occulter performance is analyzed in light of experiments and optical models, and prospects for further progress are summarized. The science capability of the hybrid Lyot coronagraph is compared with requirements for ACCESS, a representative space coronagraph concept for the direct imaging and spectroscopy of exoplanet systems. This work has been supported by NASA’s Strategic Astrophysics Technology / Technology Demonstrations for Exoplanet Missions (SAT/TDEM) program.

Space-based coronagraphs for future earth-like planet detection will require focal plane wavefront control techniques to achieve the necessary contrast levels. These correction algorithms are iterative and the control methods require an estimate of the electric field at the science camera, which requires nearly all of the images taken for the correction. We demonstrate a Kalman filter estimator that uses prior knowledge to create the estimate of the electric field, dramatically reducing the number of exposures required to estimate the image plane electric field. In addition to a significant reduction in exposures, we discuss the relative merit of this algorithm to other estimation schemes, particularly in regard to estimate error and covariance. As part of the reduction in exposures we also discuss a novel approach to generating the diversity required for estimating the field in the image plane. This uses the stroke minimization control algorithm to choose the probe shapes on the deformable mirrors, adding a degree of optimality to the problem and once again reducing the total number of exposures required for correction. Choosing probe shapes has been largely unexplored up to this point and is critical to producing a well posed set of measurements for the estimate. Ultimately the filter will lead to an adaptive algorithm which can estimate physical parameters in the laboratory and optimize estimation.

Thanks to the use of aspheric optics for lossless apodization, the Phase Induced Amplitude Apodization (PIAA) coronagraph offers full throughput, high contrast and small inner working angle. It is therefore ideally suited for space-based direct imaging of potentially habitable exoplanets. The concept has evolved since its original formulation to mitigate manufacturing challenges and improve performance. Our group is currently aiming at demonstrating PIAA coronagraphy in the laboratory to 1e-9 raw contrast at 2 λ/D separation. Recent results from the High Contrast Imaging Testbed (HCIT) at JPL demonstrate contrasts about one order of magnitude from this goal at 2 λ/D. In parallel with our high contrast demonstration at 2 λ/D, we are developing and testing new designs to reduce inner working angle and improve performance in polychromatic light. The newly developed PIAA complex mask coronagraph (PIAACMC) concept provides total starlight extinction and offers full throughput with a sub- λ/D inner working angles. We also describe a recent laboratory demonstration of fine pointing control with PIAA.

The count rate non-linearity of near-infrared devices was first found in the HST NICMOS. In this report we present a physical model of the cause of this effect, show how it is related to persistence, and compare the predictions of the model to other observations of anomalous detector behavior. This model is able to explain not only the count rate non-linearity but also several other effects. Overall, the excellent agreement between this model and the observations gives us strong confidence that we understand the underlying cause of the count rate non-linearity. This understanding should allow us to develop methods to accurately calibrate and remove the effect from JWST observations.

The grid PRF photometry method Dphot detects and measures point sources and extended sources using the Basic Calibrated Data images from the Spitzer Space Telescope without prior source position information. A mosaic is not used. Point sources with separations as small as 1.0 arcsec can be detected and measured. Examples of Dphot photometry are presented for 47 Tuc, the Galactic Center, Einstein Cross, and galaxies in GOODS North.

An iterative Fourier-transform algorithm was implemented to reconstruct the phase function of an imaging system using a point source (a single mode ber) and extended sources (pinholes) as the object. The results indicate that as the objects size is increased the phase retrieval is largely unaected until it grows to a critical diameter. At this point the phase retrieval results become highly unstable. The critical diameter at which this transition occurs is considerably smaller than predicted by the Rayleigh criterion. In this paper, we will present a detailed description of the imaging system, the source objects and the experimental results.

The special properties of Volume Bragg Gratings (VBGs) make them good candidates for spectrometry applications where high spectral resolution, low level of straylight and low polarisation sensitivity are required. Therefore it is of interest to assess the maturity and suitability of VBGs as enabling technology for future ESA missions with demanding requirements for spectrometry. The VBGs suitability for space application is being investigated in the frame of a project led by CSL and funded by the European Space Agency. The goal of this work is twofold: first the theoretical advantages and drawbacks of VBGs with respect to other technologies with identical functionalities are assessed, and second the performances of VBG samples in a representative space environment are experimentally evaluated. The performances of samples of two VBGs technologies, the Photo-Thermo-Refractive (PTR) glass and the DiChromated Gelatine (DCG), are assessed and compared in the Hα, O₂-B and NIR bands. The tests are performed under vacuum condition combined with temperature cycling in the range of 200 K to 300K. A dedicated test bench experiment is designed to evaluate the impact of temperature on the spectral efficiency and to determine the optical wavefront error of the diffracted beam. Furthermore the diffraction efficiency degradation under gamma irradiation is assessed. Finally the straylight, the diffraction efficiency under conical incidence and the polarisation sensitivity is evaluated.

Direct imaging of exoplanets requires the detection of very faint objects orbiting close to very bright stars. In this context, the SPICES mission was proposed to the European Space Agency for planet characterization at visible wavelength. SPICES is a 1.5m space telescope which uses a coronagraph to strongly attenuate the central source. However, small optical aberrations, which appear even in space telescopes, dramatically decrease coronagraph performance. To reduce these aberrations, we want to estimate, directly on the coronagraphic image, the electric field, and, with the help of a deformable mirror, correct the wavefront upstream of the coronagraph. We propose an instrument, the Self-Coherent Camera (SCC) for this purpose. By adding a small "reference hole" into the Lyot stop, located after the coronagraph, we can produce interferences in the focal plane, using the coherence of the stellar light. We developed algorithms to decode the information contained in these Fizeau fringes and retrieve an estimation of the field in the focal plane. After briefly recalling the SCC principle, we will present the results of a study, based on both experiment and numerical simulation, analyzing the impact of the size of the reference hole.

In measuring the figure error of an aspheric optic using a null lens, the wavefront contribution from the null lens must be independently and accurately characterized in order to isolate the optical performance of the aspheric optic alone. Various techniques can be used to characterize such a null lens, including interferometry, profilometry and image-based methods. Only image-based methods, such as phase retrieval, can measure the null-lens wavefront in situ – in single-pass, and at the same conjugates and in the same alignment state in which the null lens will ultimately be used – with no additional optical components. Due to the intended purpose of a null lens (e.g., to null a large aspheric wavefront with a near-equal-but-opposite spherical wavefront), characterizing a null-lens wavefront presents several challenges to image-based phase retrieval: Large wavefront slopes and high-dynamic-range data decrease the capture range of phase-retrieval algorithms, increase the requirements on the fidelity of the forward model of the optical system, and make it difficult to extract diagnostic information (e.g., the system F/#) from the image data. In this paper, we present a study of these effects on phase-retrieval algorithms in the context of a null lens used in component development for the Climate Absolute Radiance and Refractivity Observatory (CLARREO) mission. Approaches for mitigation are also discussed.

To evaluate space-based coronagraphic techniques, end-to-end modeling is necessary to simulate realistic fields containing speckles caused by wavefront errors. Real systems will suffer from pointing errors and thermal and motioninduced mechanical stresses that introduce time-variable wavefront aberrations that can reduce the field contrast. A loworder wavefront sensor (LOWFS) is needed to measure these changes at a sufficiently high rate to maintain the contrast level during observations. We implement here a LOWFS and corresponding low-order wavefront control subsystem (LOWFCS) in end-to-end models of a space-based coronagraph. Our goal is to be able to accurately duplicate the effect of the LOWFS+LOWFCS without explicitly evaluating the end-to-end model at numerous time steps.

The main components of the SPICA coronagraphic instrument have initially been bar-code apodizing masks, i.e. shaped pupils optimized in one dimension. Their free-standing designs make them manufacturable without a glass substrate, which implies an absolute achromaticity and no additional wavefront errors. However, shaped pupils can now be optimized in two dimensions and can thus take full advantage of the geometry of any arbitrary aperture, in particular obstructed apertures such as SPICA's. Hence, 2D shaped pupils often have higher throughputs while offering the same angular resolutions and contrast. Alternatively, better resolutions or contrast can be obtained for the same throughput. Although some of these new masks are free-standing, this property cannot be constrained if the optimization problem has to remain convex linear. We propose to address this issue in different ways, and we present here examples of freestanding masks for a variety of contrasts, and inner working angles. Moreover, in all other coronagraphic instruments, contrast smaller than 10^-5 can only be obtained if a dedicated adaptive optics system uses one or several deformable mirrors to compensate for wavefront aberrations. The finite number of actuators sets the size of the angular area in which quasi-static speckles can be corrected. This puts a natural limit on the outer working angle for which the shaped pupils are designed. The limited number of actuators is also responsible for an additional diffracted energy, or quilting orders, that can prevent faint companions to be detected. This effect can and must be taken into account in the optimization process. Finally, shaped pupils can be computed for a given nominal phase aberration pattern in the pupil plane, although the solutions depend in this case on the observation wavelength. We illustrate this possibility by optimizing an apodizer for the James Webb space telescope, and by testing its chromaticity and its robustness to phase changes.

A stellar coronagraph system for direct observations of extra solar planets is under development by combining unbalanced nulling interferometer (UNI), adaptive optics, and a focal plane coronagraph ^{1, 2, 3, 4, 5}. It can reach a high contrast as using lambda/10000 precision optics by lambda/1000 quality ones. However, a sufficiently high contrast has yet to be obtained for the experiment. It is thought that the remaining speckle noise at the final coronagraph focal plane detector is produced by a “non-common path error” of lambda/100 level, which is a wavefront error of differences between the coronagraph and a wavefront sensor (WFS) of adaptive optics, even when the WFS indicates lambda/1000 conversion. The non-common path error can be removed by the focal plane sensing method of wavefront correction by wavefront sensing at the final focal plane detector, although it has an issue of operation for very faint targets because of a slow feedback loop. In the present paper, we describe how our coronagraph system becomes practically higher contrast by upgrading the control method of adaptive optics with the WFS assisted by a focal plane wavefront sensing. Then, we control a wavefront error by two feedback loops, the first of which uses a WFS to make fast control for telescope optics deformation and the second of which uses a focal plane detector to compensate for the non-common path error with slow control. We show experiment results of the coronagraph system performance with both wavefront sensing methods.

We have been developing an immersion grating for high-resolution spectroscopy in the mid-infrared (MIR) wavelength region. A MIR (12-18 µm) high-resolution (R = 20,000-30,000) spectrograph with the immersion grating is proposed for SPICA, Japanese next-generation space telescope. The instrument will be the world's first high-resolution spectrograph in space, and it would make great impacts on infrared astronomy. To realize a high-efficiency immersion grating, optical properties and machinability of bulk materials are the critical issues. There are three candidate materials with good MIR transmittance; CdTe (n = 2.65), CdZnTe (n = 2.65), and KRS5 (n = 2.30). From measurements of transmittance with FTIR and of homogeneity with phase-shifting interferometry at 1.55 μm, we confirmed that CdZnTe is the best material that satisfies all the optical requirements. As for machinability, by applying Canon's diamond cutting (planing) technique, fine grooves that meet our requirement were successfully cut on flats for all the materials. We also managed to fabricate a small CdZnTe immersion grating, which shows a high grating efficiency from the air. For the reflective metal coating, we tried Au (with thin underlying layer of Cr) and Al on CdZnTe flats both by sputter deposition and vapor deposition. All samples are found to be robust under 77 K and some of them achieve required reflectivity. Despite several remaining technical issues, the fabrication of CdZnTe immersion grating appears to be sound.

Telescopes are placed on spacecrafts to avoid the effects of the Earth atmosphere on astronomical observations (turbulence, extinction ...). Atmospheric effects however may subsist when satellites are launched in low orbits, typically mean altitudes of the order of 700 km. We will present first in this paper how we are able to estimate the mean Earth radiation flux when we consider temperature housekeeping data recorded with a specific space solar mission having this orbit property. We will show after how some solar parameters extracted from images recorded with the on-board telescope are correlated with the Earth atmospheric radiation flux. We will also present how we find the limits of the South Atlantic Anomaly from affected images.

This paper presents the results of a laboratory experiment on a new free-standing pupil mask coronagraph for the direct observation of exoplanets. We focused on a binary-shaped pupil coronagraph, which is planned for installation in the next-generation infrared space telescope SPICA. Our laboratory experiments on the coronagraph were implemented inside a vacuum chamber (HOCT) to achieve greater thermal stability and to avoid air turbulence, and a contrast of 1.3×10^-9 was achieved with PSF subtraction. We also carried out multi-color/broadband experiments to demonstrate that the pupil mask coronagraph works, in principle, at all wavelengths. We had previously manufactured a checker-board mask, a type of binary-shaped pupil mask, on a glass substrate, which had the disadvantages of light loss by transmission, ghosting from residual reflectance and a slightly different refractive index for each wavelength. Therefore, we developed a new free-standing mask in sheet metal, for which no substrate was needed. As a result of a He-Ne laser experiment with the free-standing mask, a contrast of 1.0×10⁻⁷ was achieved for the raw coronagraphic image. We also conducted rotated mask subtractions and numerical simulations of some errors in the mask shape and WFEs. Speckles are the major limiting factor. The free-standing mask exhibited about the same ability to improve contrast as the substrate mask. Consequently, the results of this study suggest that the binary-shaped pupil mask coronagraph can be applied to coronagraphic observations by SPICA and other telescopes.

We present the Prototype-testbed for Infrared Optics and Coronagraphs (PINOCO) which is a large, multi-purpose cryogenic chamber. At present, the priority for PINOCO is to evaluate binary pupil mask coronagraphs in the mid-infrared wavelength region, which are planned to be adopted for the SPICA coronagraph instrument. In addition, various other experiments are possible using PINOCO: testing diverse high dynamic-range techniques, mirrors, active optics, infrared detectors, filters and spectral dispersion devices, the mechanics of the instruments, measurement of material properties, and so on. PINOCO provides a work space of 1m × 1m × 0.3m, of which inside is cooled to <5K. Flexible access to the work surface is possible by removing detachable plates at the four sides and on the top of the chamber. At the interface to the exterior, PINOCO is currently equipped with an optical window, electric connectors, and an interferometer stage. PINOCO is cooled by two GM-cycle cryo-coolers, so no cryogen is needed. A cooling test of PINOCO was successfully completed.

We have studied a coronagraph system with an unbalanced nulling interferometer (UNI). It consists of the UNI, adaptive optics, and a coronagraph. An important characteristic is a magnification of the wavefront aberrations in the UNI stage, which enables us to compensate for the wavefront aberrations beyond the AO systems capabilities. In our experiments, we have observed the stable aberration magnification of about 6 times and compensation to about λ/100 rms corresponding to λ/600 rms virtually. As a result, at the final focal plane of a 3-dimensional Sagnac interferometric nulling coronagraph, we have obtained the extra speckle reduction of better than 0.07 by the advantage of the UNI-PAC system. In order to obtain better contrast, we consider improvement of the optics with an 8OPM coronagraph, a dual feedback control, an unbalanced nulling interferometer with 4QPM or VVM, and a wavefront correction inside the UNI.