NASA’s TESS Mission Searches for New Worlds, Provides Exoplanet Targets for Further Studies

NASA's planet-finding observatory TESS (Transiting Exoplanet Survey Satellite) will be searching for Earth-like exoplanets beyond the solar system.

The TESS mission is scheduled to launch in June 2018, and it will survey 200,000 of the brightest stars near the sun to discover new exoplanets that will be targeted for follow-up studies by ground-based observatories Hubble Space Telescope and the James Webb Space Telescope. According to NASA, astronomers are anticipating the possibility that the three space missions could be studying the sky at the same time in the near future.

TESS will target exoplanets around closer and brighter stars, as they produce stronger signals than those around distant stars. The planets have a higher signal-to-noise ratio, which is the ratio of useful information (signal) to non-useful information (noise) that the telescope gets, NASA said.

The signals might also include a chemical sampling of an exoplanet's atmosphere. The goal of follow-up observations is to determine the atmosphere of exoplanets by looking at the chemical signatures of the light passing through them. This will help scientists determine whether an exoplanet could be habitable.

"There are a couple of things we like to see as a potential for habitability - one of them is water, which is probably the single most important, because as far as we know, all life that we're familiar with depends on water in some way," Stephen Rinehart, TESS project scientist at NASA's Goddard Space Flight Center, said in the same statement.

"The other is methane, which on our Earth is produced almost entirely biologically. When you start seeing certain combinations of all of these things appearing together - water, methane, ozone, oxygen - it gives you a hint that the chemistry is out of equilibrium. Naturally, planets tend to be chemically stable. The presence of life throws off this balance."

TESS will conduct the initial roundup of exoplanets and hopes to identify thousands more during its two-year mission. One of its main goals is to identify 50 rocky planets, like Earth or Venus.

"The search for exoplanets is a bit like a funnel where you pour in lots of stars," Sara Seager, TESS deputy science director at the Massachusetts Institute of Technology (MIT), said in a statement. "At the end of the day, you have loads of planets, and from there you need to find the rocky ones."

Apart from the exoplanet survey, TESS's Guest Investigator (GI) program will also look at variable objects, such as flare stars, active galaxies, supernovae and even gamma-ray bursts, providing follow-up targets not only for the Hubble and Webb telescopes but for every ground- and space-based observatory the agency plans to build over the next two decades.