Current status of the REDSoX sounding rocket

The Rocket Experiment Demonstration of a Soft X-ray Polarimeter (REDSoX Polarimeter) is a sounding rocket mission that will make the first measurement of linear X-ray polarization below 1 keV. REDSoX's design uses Wolter I focusing optics and disperses the X-rays using critical angle transmission gratings. The dispersion of those gratings is matched to laterally-graded multilayers (LGML) such that the Bragg condition is satisfied across the 0.2-0.4 keV band, reflecting the linearly polarized x-rays efficiently onto our detectors. We will use three LGMLs arranged 120 degrees to one another to allow us to measure all three Stokes parameters at once. We expect to achieve a modulation factor of over 90%. Approaching two years since the project was selected, we present an update on our progress and challenges during the design phase, and also look ahead to an eventual launch in year five. REDSoX's goals are to train early career scientists and to serve as a technical demonstration for a possible orbital mission, the Globe Orbiting Soft X-ray Polarimeter (GOSoX).