page_title: Transiting Exoplanet Survey Satellite
section_title: Science objectives
hierarchical_section_title: Transiting Exoplanet Survey Satellite / Mission overview / Science objectives
caption_attribution_description: English: The Transiting Exoplanet Survey Satellite (TESS) took this snapshot of the Large Magellanic Cloud (right) and the bright star R Doradus (left) with just a single detector of one of its cameras on Tuesday, Aug. 7. The frame is part of a swath of the southern sky TESS captured in its “first light” science image as part of its initial round of data collection.
context_page_description: The Transiting Exoplanet Survey Satellite is a space telescope for NASA's Explorers 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 April 18, 2018, atop a Falcon 9 rocket and was placed into a highly elliptical 13.7-day orbit around the Earth. The first light image from TESS was taken on August 7, 2018, and released publicly on September 17, 2018.
  Over the course of the two-year primary mission, TESS is expected to ultimately detect about 1250 transiting exoplanets orbiting the targeted stars, and an additional 13,000 transiting planets orbiting additional stars in the fields that TESS observed. As of 10 May 2020, TESS has identified 1835 candidate exoplanets, of which 46 have been confirmed so far. After the end of the primary mission around July 4, 2020, data from the prime mission will continue to be searched for planets, while the extended mission will continue to acquire additional data.
  The primary mission objective for TESS is to survey the brightest stars near the Earth for transiting exoplanets over a two-year period.
context_section_description: TESS's two-year all-sky survey will focus on nearby G-, K-, and M-type stars with apparent magnitudes brighter than magnitude 12. Approximately 200,000 stars will be studied, including the 1,000 closest red dwarfs across the whole sky, an area 400 times larger than that covered by the Kepler mission. TESS is expected to discover more than 20,000 transiting exoplanets, including 500 to 1000 Earth-sized planets and super-Earths. Of those discoveries, an estimated 20 could be super-Earths located in the habitable zone around a star. The stated goal of the mission is to determine the masses of at least 50 Earth-sized planets (at most 4 times earth radii).  Most detected exoplanets are expected to be between 30 and 300 light-years away. 
  The survey is broken up into 26 observation sectors, each sector being 24° × 96°, with an overlap of sectors at the ecliptic poles to allow additional sensitivity toward smaller and longer-period exoplanets in that region of the celestial sphere. The spacecraft will spend two 13.7-day orbits observing each sector, mapping the southern hemisphere of sky in its first year of operation and the northern hemisphere in its second year. The cameras actually take images every 2 seconds, but all the raw images would represent much more data volume than can be stored or downlinked. To deal with this, cutouts around 15,000 selected stars (per orbit) will be coadded over a 2-minute period and saved on board for downlink, while full-frame images will also be coadded over a 30-minute period and saved for downlink. The actual data downlinks will occur every 13.7 days near perigee.  This means that during the 2 years, TESS will continuously survey 85% of the sky for 27 days, with certain parts being surveyed across multiple runs.  The survey methodology was designed such that the area that will be surveyed, essentially continuously, over an entire year (351 observation days) and makes up about 5% of the entire sky, will encompass the regions of sky (near the ecliptic poles) which will be observable at any time of year with the JWST.
  In October 2019, Breakthrough Listen started a collaboration with scientists from the TESS team to look for signs of advanced extraterrestrial life. Thousands of new planets found by TESS will be scanned for "technosignatures" by Breakthrough Listen partner facilities across the globe. Data from TESS monitoring of stars will also be searched for anomalies.
caption: TESS – first light
  (August 7, 2018)[1][10][11]
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