ASTID

A Nanosatellite Concept Study to Find Transiting Earth Analogs Around the Brightest Sun-Like Stars

PI: Sara Seager

We stand on a great divide in the detection and study of exoplanets. On one side of this divide are the numerous giant exoplanets with measured densities and atmospheric temperatures. On the other side lies the possibility, as yet unrealized, of detecting and characterizing a true Earth analog (an Earth-size planet orbiting a sun-like star in a 1 AU orbit). Our team will bridge this divide by developing a concept for “ExoplanetSat”, a nanosatellite capable of continuously monitoring one nearby, bright star for 18 months to search for transiting Earths. The concept study will flow to a mission involving a suite of nanosatellites to monitor the brightest stars – stars too widely separated across the sky for a single telescope to continuously monitor. The primary engineering objective is to develop an attitude control system to point a 3kg, 10cmx10cmx30cm nanosatellite to within a few arcseconds and to develop camera image stabilization hardware and software, using piezoelectric actuators, to keep the star to a fraction of a camera pixel. Low cost, low risk, and flexible launch opportunities will be enabled by utilizing the P-POD design and low-Earth orbit. The primary science objective is to determine which stars offer the best opportunity for discovery of transits, given each star’s spectrum, wavelength-dependent variability, location on the sky, and feasible instrumental parameters. Because only planets with the highest signal-to-noise transits will allow follow-up mass and atmospheric biosignature measurements, targeted searches for transiting planets around the brightest sun-like stars are critical. A nanosatellite mission is a cost-effective opportunity to monitor the top priority stars, immediately. These facts compensate for the low probability of Earth-analog transits for any individual star. The educational objective is to enable undergraduate and graduate students to get hands-on experience with all aspects of a space mission, from concept study to flight.