What does TESS stand for? 

TESS

Transiting Exoplanet Survey Satellite (TESS, Explorer 95 or MIDEX-7) is a space telescope for NASA's Explorer program, designed to search for exoplanets using the transit method in an area 400 times larger than that covered by the Kepler mission. It was launched on 18 April 2018, atop a Falcon 9 launch vehicle and was placed into a highly elliptical 13.70-day orbit around the Earth. The first light image from TESS was taken on 7 August 2018, and released publicly on 17 September 2018.Over the course of the two-year primary mission, TESS was expected to ultimately detect about 1,250 transiting exoplanets orbiting the targeted stars, and an additional 13,000 transiting planets orbiting additional stars in the fields that TESS would observe. As of 5 November 2022, TESS had identified 5,969 candidate exoplanets, of which only 268 had been confirmed and 1720 had been dismissed as false positives. After the end of the primary mission around 4 July 2020, data from the primary mission continue to be searched for planets, while the extended missions continues to acquire additional data. The primary mission objective for TESS was to survey the brightest stars near the Earth for transiting exoplanets over a two-year period.The TESS satellite uses an array of wide-field cameras to perform a survey of 85% of the sky. With TESS, it is possible to study the mass, size, density and orbit of a large cohort of small planets, including a sample of rocky planets in the habitable zones of their host stars. TESS provides prime targets for further characterization by the James Webb Space Telescope (JWST), as well as other large ground-based and space-based telescopes of the future. While previous sky surveys with ground-based telescopes have mainly detected giant exoplanets and the Kepler space telescope has mostly found planets around distant stars that are too faint for characterization, TESS finds many small planets around the nearest stars in the sky. TESS records the nearest and brightest main sequence stars hosting transiting exoplanets, which are the most favorable targets for detailed investigations. By providing such detailed information about planetary systems with hot Jupiters, TESS makes it possible to better understand the architecture of such systems.TESS uses a novel highly elliptical orbit around the Earth with an apogee approximately at the distance of the Moon and a perigee of 108,000 km (67,000 mi). TESS orbits Earth twice during the time the Moon orbits once, a 2:1 resonance with the Moon. The orbit is expected to remain stable for a minimum of ten years. Led by the Massachusetts Institute of Technology (MIT) with seed funding from Google, on 5 April 2013, it was announced that TESS, along with the Neutron Star Interior Composition Explorer (NICER), had been selected by NASA for launch.On 18 July 2019, after the first year of operation, the southern portion of the survey was completed, and the northern survey was started. The primary mission ended with the completion of the northern survey on 4 July 2020, which was followed by the first extended mission. The first extended mission concluded in September 2022 and the spacecraft entered its second extended mission which should last for another three years.

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