The Solar Polarization and Directivity X-Ray Experiment (PADRE) is a NASA CubeSat mission built at just under 20 x 20 x 36cm, that orbits Earth. On it live two instruments, working in tandem to provide important insights into the behavior of high-energy electrons accelerated during solar flare events, helping refine models for space weather.
SHARP (Solar Hard X-ray Polarimeter) directly measures the azimuthal scattering distribution of HXRs using a cylindrical beryllium scatterer. Surrounding the scatterer are 8 ~1 mm-thick CdTe photon-counting detectors, instrumented with Timepix3 ASICs. By watching where the scattered photons go as the ship rotates (at 1 RPM), and because scattering peaks perpendicular to the incoming polarization plane, the incoming linear polarization of the HXRs can be determined.
MeDDEA (Measuring Directivity to Determine Electron Anisotropy) is composed of four flight-spare detectors from STIX (The Spectrometer/Telescope for Imaging X-rays) beneath metal filters that ensure only HXR’s reach the detectors. While MeDDEA isn’t as complex as STIX, its measurements aren’t compromised, remaining precise and accurate.
