After a little over three months in space, NASA’s newest planet-hunting spacecraft has begun scouring the galaxy for other worlds. The space observatory, dubbed TESS, officially started science operations on July 25th, which means the vehicle has been taking images of nearby stars with its four cameras to see if any planets might be lurking around them. TESS will transmit its first observations down to Earth sometime in August. It will then continue to send new information periodically for at least the next two years.
On April 18th, a SpaceX Falcon 9 rocket launched TESS into a super elliptical orbit around Earth, which is its permanent route to look for planets outside our Solar System, or exoplanets. TESS is specifically looking for planets that may exist around the closest stars to Earth, ones that are only tens to hundreds of light-years away. TESS will try to find planets that pass “in front” of these stars, periodically dimming their brightness. Nearby stars are much brighter than stars that are thousands of light-years away, and that will make it easier for scientists to study the exoplanets that TESS finds. Researchers will hopefully be able to learn more about these exoplanets through follow-up observations, such as what they’re made of and what’s in their atmospheres.
TESS’s orbit around Earth takes 13.7 days to complete, and it brings the vehicle as far out as the distance of the Moon. During its time away from our planet, it stares at the same patches of sky for long periods of time, snapping photos. Then, when TESS gets close to Earth on each orbit, the spacecraft will spend about 16 hours transmitting all of that data to huge ground-based antennas that are part of NASA’s Deep Space Network. The plan is to do this routine for each orbit until the end of the mission, which is slated for two years from now.
However, the type of orbit TESS inhabits is incredibly stable, allowing the spacecraft to keep hunting exoplanets well beyond two years. “If you get a little bit off, the Moon tends to kick you back into the orbit you’re supposed to be on,” Stephen Rinehart, the project scientist for TESS at NASA, told The Verge in April about TESS’s orbit. “This orbit could be stable for more than 100 years.” So TESS’s science routine may last for many years to come.