The Transiting Exoplanet Survey Satellite

A transiting planet invites us to measure its size, mass, orbital parameters, atmospheric composition, and other characteristics. But the invitation can only be accepted if the host star is bright enough for precise measurements of its flux and spectrum. NASA's Transiting Exoplanet Survey Satellite (TESS) is dedicated to finding such favorable systems. Operating from a 13.7-day elliptical orbit around the Earth, TESS uses four 10.5 cm telescopes to capture optical images of a 24 x 96 degree field of view. By shifting the field of view every 27 days, TESS can survey most of the sky every few years. In its first six years, TESS has identified approximately 7,000 planet candidates, with several hundred confirmed as planets. Mass measurements of these planets allow astronomers to differentiate between rocky "super-Earths" and gas-rich or volatile-rich "mini-Neptunes," while observations with the James Webb Space Telescope are revealing the secrets of their atmospheres. TESS has discovered planets orbiting a wide range of stars, including young stars, low-mass stars, binary stars, and even a white dwarf star. Beyond planet detection, TESS probes the optical variability of stars and a diverse array of other astronomical objects, including asteroids, comets, supernovae, and active galactic nuclei.