Which NASA telescope launched in 2018 to survey nearby stars for transiting exoplanets? The answer is TESS.
TESS stands for Transiting Exoplanet Survey Satellite. NASA launched it on 18 April 2018 aboard a SpaceX Falcon 9 from Cape Canaveral. Its cameras search for repeated, shallow drops in a star's brightness when an orbiting planet passes between the star and the spacecraft—a phenomenon called a transit.
The mission was designed to survey the brightest nearby stars, making its discoveries especially valuable for follow-up observations. TESS observes about 85% of the sky and uses four wide-field cameras. Unlike Hubble, which is a general-purpose observatory, TESS is primarily a planet-finding survey mission. Chandra specializes in X-rays, while Spitzer was an infrared space telescope that ended its mission in 2020.
TESS began science operations in July 2018. Its data can reveal a planet's orbital period and approximate size; astronomers often combine transit measurements with radial-velocity data to estimate mass and density. The mission has also supplied promising targets for atmospheric studies with the James Webb Space Telescope.