NASA’s Transiting Exoplanet Survey Satellite (TESS) has completed its primary mission, having spent the last two years scanning the sky for evidence of exoplanets. The satellite wrapped up its mission last month with 66 confirmed exoplanets and another 2,100 candidates. That’s already a giant pile of data for scientists to pore over, and TESS isn’t done yet. The satellite has started an extended mission that will run through September 2022.
TESS headed into space in April 2018 with the aid of a SpaceX Falcon 9 rocket. After a systems check that included snapping a photo of a comet, TESS went to work scanning the entire sky for evidence of exoplanets in our galactic neighborhood. The TESS mission is something of a spiritual successor to Kepler, which began experiencing hardware failures several years ago. NASA finally retired Kepler just a few months after TESS launched. Like Kepler, TESS uses the transit method to detect exoplanets — it watches for repeating dips in luminance from stars which could indicate a planet passing between the star and Earth.
The satellite has four wide-angle telescopes, allowing it to monitor large parts of the sky as it orbits. NASA calls this an “all-sky transiting exoplanet survey” because TESS was designed to gather unobstructed panoramic data from both the northern and southern hemispheres. Unlike Kepler, TESS only observed stars out to a distance of 300 light-years. Kepler looked much farther away but in a narrow field of view. TESS can give us a better idea of what exoplanets are nearby, and therefore easy to study.
Patricia Boyd, the project scientist for TESS at NASA’s Goddard Space Flight Center, says TESS is already a “roaring success.” It spotted the Earth-like exoplanet HD 21749c, three planets in the GJ 357 system (including one potentially habitable), and even saw a star slipping into a black hole. It will take years for scientists to comb through all the data from TESS’ primary mission to see which of those 2,100 candidate planets are really there.
Going forward, NASA expects to get even more data from the satellite. The team has introduced improved observation and processing technology, which allows TESS to capture an image of the sky every 10 minutes. That’s three times faster than during the primary mission. We can look forward to many more discoveries courtesy of TESS.