TESS Completes Its Primary Mission

On July 4, NASA’s Transiting Exoplanet Survey Satellite (TESS) completed its primary mission, a two-year-long survey that imaged about 75% of the starry sky. In capturing this giant mosaic, TESS has found 66 new exoplanets, or worlds beyond our solar system, as well as nearly 2,100 candidates astronomers are working to confirm.

TESS monitors 24-by-96-degree strips of the sky, called sectors, for about a month using its four cameras. The mission spent its first year observing 13 sectors comprising the southern sky and then spent another year imaging the northern sky.

Now in its extended mission, TESS has turned around to resume surveying the south. In addition, the TESS team has introduced improvements to the way the satellite collects and processes data. Its cameras now capture a full image every 10 minutes, or three times faster than during the primary mission. The faster measurements will allow TESS to better resolve brightness changes caused by stellar oscillations and to capture explosive flares from active stars in greater detail.

These changes will remain in place for the duration of the extended mission, which will be completed in September 2022. After spending a year imaging the southern sky, TESS will take another 15 months to collect additional observations in the north and to survey areas along the ecliptic – the plane of Earth’s orbit around the Sun – that the mission has not yet imaged.

TESS looks for transits, the telltale dimming of a star caused when an orbiting planet passes in front of it from our point of view. During its primary mission, TESS also observed the outburst of a comet in our solar system, as well as numerous exploding stars, and even watched as a black hole in a distant galaxy shredded a Sun-like star.