Principal Investigator Sara Seager
Co-investigator David Miller
Project Website http://ssl.mit.edu/newsite/research/project_profile.php?key=2
ExoplanetSat is a nanosatellite space telescope that will search for transiting exoplanets around the brightest Sun-like stars in the sky. The spacecraft is a 3U CubeSat, measuring 10 x 10 x 34 cm with a mass of approximately 5 kg, and will monitor a single star at a time from low Earth orbit (LEO). The optical payload consists of a combined star camera and science photometer. The star camera provides inertial attitude estimates and the photometer precisely measures stellar brightness, seeking the characteristic dip in intensity that indicates a transiting exoplanet. The ExoplanetSat prototype will serve as the basis of an eventual fleet of nanosatellites that provides more complete coverage of the sky. Given sub-pixel sensitivity variations in the science detector, image jitter and the resulting impact on photometric precision is of concern. The attitude determination and control subsystem (ADCS) mitigates this effect using a two-stage pointing control architecture that combines 3-axis reaction wheels for arcminute-level coarse pointing with a piezoelectric translation stage at the focal plane for fine image stabilization to the arcsecond level.