Aspera Payload Design Overview: UV SmallSat Mission to Detect and Map Warm-hot Halo Gas around the Nearby Galaxies

Aspera is a NASA-funded UV SmallSat Pioneers mission designed to detect and map warm-hot phase halo gas around nearby galaxies. The Aspera payload is designed to detect faint diffuse O VI emission at around 103.2 nm, satisfying the sensitivity requirement of 5E-19 erg/s/cm^2/arcsec^2 over 179 hours of exposure. In this presentation, we describe the overall payload design. The payload comprises two identical co-aligned UV long-slit spectrograph optical channels sharing a common UV-sensitive Micro Channel Plate detector. The design delivers spectral resolution R ~ 2,000 over the wavelength range of 101 to 106 nm. The field of view of each channel is 1 degree by 30 arcsec, with an effective area of 1.1 cm^2. The mission is now entering Phase D, payload integration, and testing, with the projected launch-ready date set for late-2025. The mission will be launched into low-Earth orbit via rideshare.