Credits: NASA's Goddard Space Flight Center
An artist’s illustration of the Transiting Exoplanet Survey Satellite.

NASA has announced that it officially activated its latest exoplanet-hunting spacecraft TESS (Transiting Exoplanet Survey Satellite) on July 25th.


According to the NASA release, TESS is expected to transmit its first series of science data back to Earth in August, and thereafter periodically every 13.5 days, once per orbit, as the spacecraft makes it closest approach to Earth. The TESS Science Team will begin searching the data for new planets immediately after the first series arrives.

Earth-orbiting TESS will use its instruments to measure 200,000 stars within 300 light-years of our Sun. It can peep more and brighter stars than its predecessor, Kepler and K2 (two missions, one spacecraft). It will also be better at imaging exoplanets orbiting in the habitable zones of red dwarf stars like TRAPPIST-1 and nearby Proxima Centauri. Some scientists have speculated that those strange worlds could be home to extraterrestrial life.

The first order of business for TESS it to scan a patch of sky in the southern hemisphere covering 2,300 degrees from the south ecliptic pole to near the ecliptic plane. Basically, it’s looking for potential exoplanets in a strip of the sky running from the far south to near the equator. Eventually, TESS should be able to observe about 85 percent of the sky over its expected two-year mission. The first year will cover the southern hemisphere, and then it’ll move on to the northern half of the sky.



TESS uses the same technique to look for exoplanets as NASA’s Kepler mission, launched in 2009. The now-retired telescope, Kepler, focused on a single area of the sky for its first four years but, after the failure of two reaction wheels on the spacecraft ended those observations, went into an extended mission called K2, carrying out a series of “campaigns” of observations of different regions of the sky for nearly three months at a time.

TESS will create a catalog of nearby stars whose light dims periodically, signaling the presence of an orbiting planet. These stars will be candidates for follow-up observations by other telescopes, which will be able to determine their masses and other properties, like the compositions of their atmospheres.

The upcoming James Webb Space Telescope will be able to study these exoplanets in more detail, so will the European Extremely Large Telescope, Giant Magellan Telescope and the Large Synoptic Survey Telescope. These telescopes will provide life-hunting scientists with data concerning potential biosignatures, characteristic light emissions from molecules that could be indicative of life—things like organic compounds and water.

But we’ll likely have to wait until the 2040s, when future telescope will have the capabilities to make observations like those possible for planets within our own solar system, today. Finding a habitable exoplanet is a long process, but the process is in full swing.