An Automated Onboard Image Integration Control for the Star-Planet Activity Research CubeSat

M dwarfs are known to possess strong and highly variable ultraviolet (UV) radiation that might play an important role in the habitability and atmospheric loss of their planets. The Star-Planet Activity Research CubeSat (SPARCS) is a dedicated space-based observatory that will photometrically monitor the flaring activity of a sample of M dwarfs of different ages simultaneously at near-UV and the far-UV wavelengths. Hence, the mission adopts a 9-cm reflective telescope to project a 40’ field-of-view onto two back-illuminated delta-doped CCDs with high UV quantum efficiency. To achieve its science objective, the satellite is equipped with a dedicated science payload processor that manages detector thermal control as well as science observations, and performs near-real time image reduction and aperture photometry in order to automatically and actively control subsequent integration times and gains when flaring events are detected. We present the approach adopted for the SPARCS dynamic exposure control loop and its pre-flight tests and performance using synthetic M dwarf light curves and full-frame images in the two SPARCS passbands.

Acknowledgements: Funding for SPARCS is provided by NASA’s Astrophysics Research and Analysis program, NNH16ZDA001N.