|Following a three-year competition, NASA recently selected the Transiting Exoplanet Survey Satellite (TESS) project at MIT for a planned launch in 2017.|
Credit: MIT KAVLI Institute for Astrophysics and Space Research
Over the next decade, NASA and the European Space Agency (ESA) aim to launch a handful of spacecraft that should discover thousands of additionalexoplanets and characterize some of the most promising — the most apparently Earthlike — new finds in detail.
These future missions are all following in the footsteps of Kepler, whose observations have revealed that the Milky Way galaxy is jam-packed with alien planets. The instrument has spotted more than 3,500 planet candidates to date; just 167 of them have been confirmed by follow-up observations so far, but mission scientists expect about 90 percent will end up being the real. [Gallery: A World of Kepler Planets]
Kepler's original planet-hunting activities came to an end this past May when the second of its four orientation-maintaining reaction wheels failed, robbing the spacecraft of its ultra-precise pointing ability. But the instrument may continue its planet search in a modified and limited fashion, as part of a possible future mission dubbed K2.
NASA is expected to make a final decision about K2, and Kepler's ultimate fate, around the middle of next year. By then, the first the exoplanet new wave will already be aloft — Europe's Gaia mission.
ESA's Gaia spacecraft is slated to blast off from French Guiana next month; its launch window extends from Dec. 17 through Jan. 5.
Gaia will head to a gravitationally stable spot about 900,000 miles (1.5 million kilometers) from Earth called the sun-Earth Lagrange Point 2. Over the next five years, the spacecraft will repeatedly measure the position, movement and brightness changes of more than 1 billion Milky Way stars — about 1 percent of the galaxy's total.
"This huge stellar census will provide the data needed to tackle an enormous range of important problems related to the origin, structure and evolutionary history of our galaxy," ESA officials write in a description of the Gaia mission. [7 Ways to Discover Alien Planets]
Exoplanet science should be one of the fields that benefits. The Gaia mission, whose total cost is 740 million euros (about $990 million), could potentially detect tens of thousands of new planetary systems, researchers say.
ESA will likely launch another exoplanet mission, called Cheops (short forCHaracterizing ExOPlanets Satellite), four years after Gaia gets off the ground.
Like Kepler, Cheops will watch for exoplanet "transits," gathering data when alien worlds cross the face of their parent stars from the instrument's perspective. But the similarities mostly end there. While Kepler stared at more than 150,000 stars simultaneously, Cheops will target one star at a time. And its chief aim is the follow-up study of known exoplanets, rather than the discovery of previously unknown worlds.
"Knowing when to look, and at which star, will make Cheops extremely efficient at providing first-step characterization of low-mass exoplanets by measuring accurate radii and densities," David Ehrenreich, of the University of Geneva, said Nov. 6 during a presentation at the second Kepler Science Conference at NASA's Ames Research Center in Moffett Field, Calif.
Another key goal of Cheops, Ehrenreich added, is "collecting the 'golden targets' for future in-depth characterization by, for instance, the James Webb Space Telescope."
Cheops' total cost is about $134 million (100 milllion Euros), Ehrenreich said. Formal adoption of the mission is expected in the next few months, with launch targeted for late 2017.