What to do when NASA's Kepler Spacecraft dies? Launch TESS.

A changing of the guard in NASA's hunt for exoplanets - SpaceNews.com

As Kepler approaches the end of its life, NASA's next mission to search for exoplanets is gearing up for launch. Technicians are completing final tests on the Transiting Exoplanet Survey Satellite (TESS), a NASA mission scheduled for launch this spring.

From article, (Sometime later this year NASA’s Kepler spacecraft, orbiting the sun more than 150 million kilometers from the Earth, will fire its thrusters for the final time. The spacecraft is running out of the hydrazine fuel used by those thrusters to maintain the spacecraft’s orientation. Once the thrusters sputter and shut down, their fuel exhausted, Kepler will no longer be able to control its pointing, and the mission will end.

NASA’s next mission to search for exoplanets is gearing up for launch. At an Orbital ATK facility near Washington Dulles International Airport, technicians are completing final tests on the Transiting Exoplanet Survey Satellite (TESS), a NASA mission scheduled for launch this spring.

TESS, like Kepler, will look for exoplanets by detecting very small changes in brightness of stars as orbiting plans cross, or transit, their disks. But while Kepler initially examined a single, small area of the sky in an effort to determine the fraction of stars with planets, TESS will instead perform an all-sky survey, focused on the brightest stars nearest to Earth.

That search is intended to find exoplanets well-suited to follow up observations by other telescopes, including the upcoming James Webb Space Telescope, that can help determine their mass and composition, and even study their atmospheres.

“TESS is tiny, but it punches above its weight,” said George Ricker, principal investigator for TESS at the Massachusetts Institute of Technology, during the 
Kepler town hall. “It’s a finder scope for JWST.”

The spacecraft, 1.5 meters tall and weighing a few hundred kilograms, will ship in early February to Florida’s Kennedy Space Center for launch processing. TESS will launch no earlier than March 20 on a SpaceX Falcon 9 rocket into an elliptical orbit that is in a 2:1 resonance with the moon.

That orbit, Ricker said, is very stable and also allows for high data rates from the spacecraft. However, it limits the days on which TESS can launch in order to phase into the proper trajectory. Ricker said there were about 40 days through June on which TESS could launch.

The four cameras on TESS will map nearly the entire sky over its two-year primary mission. Astronomers expect that TESS will detect thousands of exoplanets, many of which will be ideal for follow-up observations by other telescopes, including the James Webb Space Telescope, to characterize them. Any extended mission, Ricker said, would allow TESS to fill in gaps in observations from its primary mission or do follow-up studies in other parts of the sky.

While TESS has a two-year primary mission, Ricker said he believed that the spacecraft could operate for much longer. The stability of its orbit, he said, requires no station-keeping, and hence limits the use of thrusters. “The operational life of the mission could very well extend for more than two decades,” he said.)


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