The Transiting Exoplanet Survey Satellite (TESS) is an Explorer-class planet finder. In the first-ever spaceborne all-sky transit survey, TESS will identify planets ranging from Earth-sized to gas giants, orbiting a wide range of stellar types and orbital distances.  The principal goal of the TESS mission is to detect small planets with bright host stars in the solar neighborhood, so that detailed characterizations of the planets and their atmospheres can be performed.

TESS will monitor the brightnesses of more than 500,000 stars during a two year mission, searching for temporary drops in brightness caused by planetary transits. Transits occur when a planet’s orbit carries it directly in front of its parent star as viewed from Earth. TESS is expected to catalog more than 3000 transiting exoplanet candidates, including a sample of ~500 Earth-sized and ‘Super Earth’ planets, with radii less than twice that of the Earth. TESS will detect small rock-and-ice planets orbiting a diverse range of stellar types and covering a wide span of orbital periods, including rocky worlds in the habitable zones of their host stars.

TESS stars will be 30-100 times brighter than those surveyed by the Kepler satellite; thus,TESS planets should be far easier to characterize with follow-up observations.  These follow-up observations will provide refined measurements of the planet masses, sizes, densities, and atmospheric properties.

TESS will provide prime targets for further, more detailed characterization with the James Webb Space Telescope (JWST), as well as other large ground-based and space-based telescopes of the future. TESS’s legacy will be a catalog of the nearest and brightest stars hosting transiting exoplanets, which will comprise the most favorable targets for detailed investigations in the coming decades.

TESS team partners include the MIT Kavli Institute for Astrophysics and Space Research (MKI) and MIT Lincoln Laboratory; NASA’s Goddard Spaceflight Center; Orbital Sciences Corporation; NASA’s Ames Research Center; the Harvard-Smithsonian Center for Astrophysics; the Aerospace Corporation; and the Space Telescope Science Institute.

TESS has been selected by NASA for launch in 2017 as an Astrophysics Explorer mission.

The TESS Mission

TESS will monitor the full celestial sphere in a two-year mission. The observation strategy is “stare and step”. The brightnesses of up to 25,000 stars in a 24°x96° sector of the sky opposite the Sun are measured continuously for 27 days. The field-of-view of the cameras is then stepped 27° east, and a new sector of sky is monitored. Overlap between successive observation sectors allows a subset of stars to be monitored for longer periods, up to six months near the ecliptic poles.

The TESS High-Earth Orbit (HEO) is in a 2:1 resonant orbit with the moon, meaning its orbital period is half of that of the moon, or 13.7 days.  In HEO, TESS is afforded continuous viewing of the anti-solar sky for >27 days per month. The HEO provides a very stable environment for exoplanet observations, allowing for sensitivities of less than 60 ppm for the brightest stars.

TESS Science Team

  • Principal Investigator:  George Ricker
  • Deputy Principal Investigator:  Roland Vanderspek
  • Deputy Project Manager:  Joseph Scillieri

Meet the full team.


Ricker et al., “Transiting Exoplanet Survey Satellite,” Journal of Astronomical Telescopes, Instruments, and Systems 1(1), 014003 (Jan–Mar 2015)

News/Press Releases

NASA Awards Launch Services Contract for Transiting Exoplanet Survey Satellite (December 16, 2014)

NASA’s TESS Mission Cleared for Next Development Phase (November 7, 2014)

NASA selects MIT-led TESS project for 2017 mission  (April 25, 2013)

NASA Selects Explorer Investigations for Formulation (April 5, 2013)

MIT’s TESS project awarded $1M NASA grant  (October 4, 2011)

Related Multimedia

Spotlight Live:  TESS & the Search for Exoplanets  (May 1, 2013)

Exoplanets: The Next Frontier | An interview with Sara Seager (June 21, 2013)

Additional information about TESS