TESS

TESS
Name	Transiting Exoplanet Survey Satellite
Caption	Model of the TESS spacecraft
Mission type	Exoplanet survey
Operator	NASA / MIT
Website	https://tess.mit.edu
Mission duration	2 years (planned), Elapsed: 6 years, 1 month, 24 days
Spacecraft	TESS
Manufacturer	Orbital ATK
Launch mass	362 kg
Launch date	18 April 2018, 22:51 UTC
Launch rocket	Falcon 9 Block 4
Launch site	Cape Canaveral SLC-40
Orbit reference	Geocentric orbit
Orbit regime	Highly elliptical orbit
Orbit periapsis	108,000 km
Orbit apoapsis	375,000 km
Orbit period	13.7 days
Orbit inclination	37°
Telescope type	Wide-angle telescope
Telescope diameter	10.5 cm (4 lenses)
Telescope focal length	f/1.4
Telescope wavelength	600–1000 nm
Instruments	Four CCD cameras

TESS. The Transiting Exoplanet Survey Satellite is a NASA-led Astrophysics mission designed to search for exoplanets using the transit method. Launched in April 2018 aboard a SpaceX Falcon 9 rocket, its primary goal is to identify small planets orbiting the brightest stars in the Solar neighborhood. The mission is managed by the MIT and the Goddard Space Flight Center, with significant contributions from partners like the Harvard-Smithsonian Center for Astrophysics.

Overview

Conceived as a successor to the highly successful Kepler mission, TESS was selected in 2013 as part of NASA's Explorers Program. The mission aims to conduct an all-sky survey, monitoring over 200,000 of the nearest and brightest main-sequence stars for temporary dips in brightness caused by planetary transits. This systematic approach is designed to provide prime targets for further characterization by future observatories, including the James Webb Space Telescope. The project is led by principal investigator George R. Ricker of MIT.

Mission and objectives

The core scientific objective is to discover thousands of exoplanets, with an emphasis on rocky worlds in the habitable zones of their host stars. TESS specifically targets M-dwarf stars, which are smaller and cooler than the Sun, as planets orbiting them have stronger transit signals and shorter orbital periods. A key goal is to measure the masses of at least 50 small planets with radii less than four times that of Earth. The mission also supports a robust Guest Observer program, allowing the wider scientific community to propose additional targets for study.

Spacecraft and instruments

The spacecraft bus was built by Orbital ATK (now part of Northrop Grumman) and is based on the LEOStar-2 platform. Its primary payload consists of four identical wide-field cameras, each equipped with a custom CCD detector from MIT Lincoln Laboratory. Each camera has a 24° × 24° field of view, and together they create a combined observing sector of 24° × 96°. The cameras are sensitive to red and near-infrared light, optimized for observing cool M-dwarf stars. The spacecraft also carries a data handling unit and communicates via the Deep Space Network.

Orbit and operations

TESS operates in a unique, stable 2:1 resonant orbit with the Moon, known as a P/2 orbit. This highly elliptical path, with a period of 13.7 days, was chosen to provide long, uninterrupted viewing periods with minimal obstruction from the Earth or Moon. The mission divides the sky into 26 overlapping sectors, observing each for approximately 27 days. The southern celestial hemisphere was surveyed in the first year of operations, followed by the northern hemisphere. This orbit also offers a stable thermal environment and reduces fuel consumption for station-keeping.

Discoveries and scientific results

TESS has confirmed thousands of exoplanet candidates, including notable discoveries like the Earth-sized world TOI 700 d in its star's habitable zone and the multi-planet system TOI-700. It identified LHS 3844 b, a hot, rocky planet, and TOI 1338 b, a circumbinary planet detected in the data by a high school intern. Beyond exoplanets, the mission's data has led to breakthroughs in stellar astrophysics, such as studying asteroseismology in stars like α Mensae, and has detected numerous supernovae, tidal disruption events, and exocomets.

Data and public archive

TESS data is processed by the Science Processing Operations Center at the NASA Ames Research Center and is publicly available through the Mikulski Archive for Space Telescopes at the Space Telescope Science Institute. The mission releases data in sectors every few months, enabling rapid follow-up by ground-based telescopes like those at the Las Cumbres Observatory and the TRAPPIST network. The public has also contributed to discovery through programs like Planet Hunters TESS, a citizen science project on the Zooniverse platform. All data products, including light curves and full-frame images, are freely accessible to the global scientific community.

Category:Space telescopes Category:Exoplanet search projects Category:NASA space probes Category:Spacecraft launched in 2018