NASA's Transiting Exoplanet Survey Satellite [wikipedia.org] (TESS [nasa.gov]) mission is set to launch on April 16 at 6:32 PM ET aboard a Falcon 9 rocket. The spacecraft was developed by MIT with seed funding in Google back in 2008 [mit.edu]. The spacecraft will perform an all-sky survey using four 24° × 24° wide field-of-view cameras that can image a total of 24° × 96° (2,300 square degrees) of sky every 30 minutes (the Sun and Moon are only about 0.2 deg2 to Earth-based observers).
TESS will use a unique "P/2" 2:1 lunar resonant orbit to image stars in both the Northern and Southern hemispheres. The survey will image 26 observation sectors of 24° × 96° each, with some overlap at the ecliptic poles. The total survey area will be about 400 times larger than the area searched by the Kepler [wikipedia.org] mission.
TESS will study about 500,000 stars, including the nearest 1,000 red dwarfs, with the goal of finding at least 3,000 new transiting exoplanet candidates. The spacecraft will study [nasa.gov] F, G, K and M type stars (spanning from F5 to M5 [wikipedia.org]), some of which are 30-100 times brighter than stars surveyed by the Kepler spacecraft. Many of the stars will be much closer to Earth than stars surveyed by Kepler, allowing for easier confirmation and follow-up measurements of exoplanets. 30-minute full-frame exposures will be used to search for transient events [nasa.gov] such as supernovae, star flares, and gamma-ray bursts.
Each observation sector will only be viewed for 27 days (at least in the initial phase of the mission), which will limit the exoplanets seen to those with shorter orbital periods. Potentially habitable exoplanet candidates will likely be found around red dwarfs rather than Sun-like stars. However, TESS's own orbit should remain stable for decades, which could mean that its mission will be extended to allow for a greater variety of exoplanets to be found.
NASA's Kepler spacecraft is running out of fuel [nasa.gov] and may not be operational beyond 2018, leaving TESS to be Earth's premier exoplanet hunter in space. The European Space Agency's (ESA) CHaracterising ExOPlanets Satellite [wikipedia.org] (CHEOPS) will launch in late 2018. It will provide precise radii [centauri-dreams.org] for exoplanets with known masses, and can follow-up on TESS observations [arxiv.org] to provide suitable targets for the James Webb Space Telescope. In 2026, ESA will launch the PLAnetary Transits and Oscillations of stars [wikipedia.org] (PLATO) space observatory, which will search for planetary transits around 300,000 to 1 million stars. PLATO will study bright stars of magnitudes between 4 and 11, and will be rotated by 90 degrees every 3 months, allowing it to continuously survey a patch of sky and discover exoplanets with longer orbital periods than TESS will.