Meet TESS, the satellite that will find thousands of planets

TESS will survey an area 400 times larger than what Kepler observed. This includes 200,000 of the brightest nearby stars. Over the course of two years, the four wide-field cameras on board will stare at different sectors of the sky for days at a time.

TESS will look for exoplanets using the transit method, observing slight dips in the brightness of stars as planets pass in front of them. Bright stars allow for easier followup study through ground- and space-based telescopes.

"TESS is helping us explore our place in the universe," said Paul Hertz, Astrophysics Division director at NASA Headquarters. "Until 20 years ago, we didn't know of any planets beyond our own solar system. We've expanded our understanding of our place in the universe, and TESS will help us keep expanding."

NASA expects TESS to allow for the cataloging of more than 1,500 exoplanets, but it has the potential to find thousands. Of these, officials anticipate, 300 will be Earth-size exoplanets or double-Earth-size Super Earths. Those planets could be the best candidates for supporting life outside our solar system. Like Earth, they are small, rocky and usually within the habitable zone of their star, meaning liquid water can exist on the surface.

"One of the biggest questions in exoplanet exploration is: If an astronomer finds a planet in a star's habitable zone, will it be interesting from a biologist's point of view?" said George Ricker, TESS principal investigator at the Massachusetts Institute of Technology's Kavli Institute for Astrophysics and Space Research in Cambridge. "We expect TESS will discover a number of planets whose atmospheric compositions, which hold potential clues to the presence of life, could be precisely measured by future observers."

These exoplanets will be studied so that NASA can determine which are the best targets for future missions, like the James Webb Space Telescope. That telescope, whose launch was just pushed back to 2020, would be able to characterize the details and atmospheres of exoplanets in ways scientists have not yet been able to do.

"We learned from Kepler that there are more planets than stars in our sky, and now TESS will open our eyes to the variety of planets around some of the closest stars," Hertz said. "TESS will cast a wider net than ever before for enigmatic worlds whose properties can be probed by NASA's upcoming James Webb Space Telescope and other missions."

NASA believes that TESS will build on Kepler's momentum and open the study of exoplanets in unprecedented ways.

"TESS is opening a door for a whole new kind of study," said Stephen Rinehart, TESS project scientist at NASA's Goddard Space Flight Center. "We're going to be able study individual planets and start talking about the differences between planets. The targets TESS finds are going to be fantastic subjects for research for decades to come. It's the beginning of a new era of exoplanet research. I don't think we know everything TESS is going to accomplish. To me, the most exciting part of any mission is the unexpected result, the one that nobody saw coming."