On April 16, NASA plans the Transit Exoplanet Survey Satellite (TESS) on a SpaceX Falcon 9 rocket. TESS is a terrestrial instrument used to discover distant planets orbiting around 200,000 stars within 300 light-years. Astronomers hope that TESS will help them learn if there are other habitable planets or not, or even beyond the solar system. TESS can not do it alone.
"TESS will find planets in the habitable zones around red dwarf stars," said Aki Roberge, NASA's research astrophysicist, in February at the annual meeting of the American Society for the Advancement of Science Austin, Texas. "But only being in the habitable zone does not mean that you are habitable."
According to a NASA publication, this satellite has four wide-field cameras that will cover around 85 percent of the sky. It will fly over the sky sector by sector to briefly fade out the light of a star pointing to a planet in orbit. It's basically a Kepler part two (or part three, considering K2 is a separate mission) – and beloved Kepler has only a few functional months left.
However, TESS has some advantages – it can see brighter stars and much more than Kepler. It will also be able to perform some spectroscopy to determine the chemical composition of these planets.
But the satellite will be particularly good at discovering perhaps another agonizing kind of planet: those orbiting red dwarf stars. Recently, planets have been discovered orbiting Proxima Centauri, TRAPPIST-1 and other cooler dwarf stars in their habitable zones. This has led some to think that these strange little stars, perhaps unlike our own hot sun, are the ones with the potential for extraterrestrial life. There are also many of them.
"It's just so much parameter space that we did not explore," Emily Rice, an astrophysicist at the American Museum of Natural History, told me in November. "You do not just want one, you want some of them to find out the general characteristics of these things."
But TESS is unlikely to find potentially habitable planets, said Padi Boyd, director of the Guest Investigator Program for the TESS -Mission the annual meeting of the American Society for the Advancement of Science in Austin, Texas. The study will allow scientists to prioritize some of the planets for further study with other telescopes, such as the recently delayed James Webb Space Telescope (JWST).
In other words: TESS will tell the other telescopes where they are pointing.
Ultimately, we might have to wait for a successor to the JWST, such as the proposed LUVOIR and HabEx missions, to actually find signs of life on another planet. We know that life has changed the chemistry of the Earth's atmosphere. These future telescope concepts may be able to map exoplanets and use their light spectra to see if these planets have similar atmospheric signatures. But TESS is a start.
"I think we can give a lot of information about whether an Earth-like planet is really habitable or not," said Boyd. "But answering that question really requires all our telescopes."