Transiting Exoplanet Survey Satellite

Transiting Exoplanet Survey Satellite is a NASA Explorers Program mission led by the Kavli Institute for Astrophysics and Space Research at the Massachusetts Institute of Technology (MIT). Designed to search for exoplanets using the transit method, it monitors the brightness of over 200,000 main sequence stars, focusing on those closest to the Solar System. The mission builds upon the legacy of the Kepler space telescope and aims to identify prime targets for further study by observatories like the James Webb Space Telescope.

Overview

Conceived as an Astrophysics mission within NASA's Science Mission Directorate, its primary goal is to discover exoplanets, particularly Earth-sized and super-Earth worlds, orbiting bright, nearby stars. The mission was selected in 2013 under the leadership of principal investigator George R. Ricker of MIT. It operates by dividing the sky into 26 sectors, observing each for approximately 27 days with its array of wide-field CCD cameras. This systematic approach allows it to cover about 85% of the sky over its two-year primary mission, far exceeding the sky coverage of the Kepler space telescope.

Mission design and spacecraft

The spacecraft bus was built by Orbital ATK (now part of Northrop Grumman) based on its LEOStar-2 platform. Its key payload consists of four identical refracting telescopes, each equipped with a 16.8-megapixel CCD detector from MIT Lincoln Laboratory, providing a combined field of view of 24° × 96°. This design enables the simultaneous observation of a vast swath of sky. The craft is stabilized on three axes and uses reaction wheels for precise pointing, with its solar arrays generating approximately 530 watts of power. Data is downlinked every 13.7 days during perigee passes to the NASA Deep Space Network ground stations.

Launch and orbit

Launched on 18 April 2018 atop a SpaceX Falcon 9 Block 4 rocket from Space Launch Complex 40 at Cape Canaveral Space Force Station, the spacecraft was initially placed into a highly elliptical Earth orbit. A series of phasing orbit maneuvers, including a final gravity assist from the Moon, established its unique 2:1 lunar resonance high Earth orbit. This stable 13.7-day orbit, with a perigee of 108,000 km and an apogee of 375,000 km, minimizes interference from Earth and the Van Allen radiation belts, allowing for long, uninterrupted observing sessions.

Science objectives and discoveries

Its core science objective is to identify exoplanet candidates, especially those in the habitable zone of M-dwarf stars, for atmospheric characterization by future missions. Within its first year, it had identified over 1,200 candidate planets, with confirmations from ground-based observatories like the Las Cumbres Observatory Global Telescope Network. Notable early discoveries include Pi Mensae c, a super-Earth around a Sun-like star, and LHS 3844 b, a hot, rocky world. It also discovered the multi-planet system TOI 700, which includes TOI 700 d, an Earth-sized planet in the habitable zone. The mission has contributed to stellar astrophysics by detecting stellar oscillations and flares on stars like Proxima Centauri.

Data and legacy

All data from the mission is publicly archived at the Mikulski Archive for Space Telescopes and released to the scientific community through the TESS Science Office at MIT. The TESS Input Catalog, compiled using data from Gaia and the Two Micron All Sky Survey, provides precise stellar parameters for its targets. Its planet candidates are followed up by numerous projects, including the TESS Follow-up Observing Program and the SPECULOOS network. The mission's extensive catalog of nearby exoplanets is a foundational resource for the James Webb Space Telescope and future flagship missions like the Nancy Grace Roman Space Telescope, cementing its role in the next era of exoplanet science.

Category:NASA space probes Category:Exoplanet search projects Category:Space telescopes Category:Explorers Program