NASA’s Transiting Exoplanet Survey Satellite (TESS) has concluded its two-year-long primary mission and has now moved on to its extended mission. Over the last 24 months, the telescope has imaged 75 percent of the sky, discovering 66 new exoplanets as well as 2,100 candidates. More will be discovered and confirmed during its extended mission.

“TESS is producing a torrent of high-quality observations providing valuable data across a wide range of science topics,” Patricia Boyd, a project scientist for TESS at NASA's Goddard Space Flight Center, said in a statement. “As it enters its extended mission, TESS is already a roaring success.”

TESS spent its first two years studying the Southern sky and then the Northern. It has now moved back to the Southern Sky for the next year. The final phase of the mission, lasting 15 months, will return to the northern sky as well as observe the ecliptic – the plane of Earth’s orbit around the Sun. This extended mission is expected to be completed in September 2022.

The extended mission will also see improvements in how the data is collected, with observations of thousands of stars possible in only a matter of seconds. TESS now captures an image of the portion of the sky it is observing every 10 minutes. In just 20 seconds, it records the brightness of thousands of stars, on top of the current methods of measuring tens of thousands of stars in a couple of minutes.

The brightness is the approachthe telescope uses to discover new planets. It is known as the transit method. If a planet moves in front of the star, TESS registers a dip in brightness. If multiple dips repeat in a regular pattern, a planet is confirmed.

TESS has discovered a wide range of worlds already, including a nearby Earth-sized world in the so-called habitable zone, where liquid water might exist. Its quick reflexes in observing the night sky has also been used to detect a star being shredded by a black hole.

The improvements will push the envelope on all these kinds of observations and continue to provide new insights into the menagerie of stars and planets in the Milky Way.