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Kepler Spacecraft Has Discovered a Trove of New Alien Planets

KISSIMMEE, Fla. — NASA's Kepler spacecraft has bounced back nicely from the malfunction that ended its original exoplanet hunt more than two years ago.

Kepler has now discovered more than 100 confirmed alien planets during its second-chance K2 mission, researchers announced Tuesday (Jan. 5) here at the 227th Meeting of the American Astronomical Society (AAS).

The $600 million Kepler mission launched in March 2009, tasked with determining how commonly Earth-like planets occur throughout the Milky Way galaxy. Kepler has been incredibly successful, finding more than 1,000 alien worlds to date, more than half of all exoplanets ever discovered. [Gallery: A World of Kepler Planets]

Image: Artist's illustration of Kepler spacecraft
The artist's illustration shows NASA's planet-hunting Kepler spacecraft operating in its second-chance K2 mission. NASA Ames/JPL-Caltech/T Pyle

The spacecraft finds planets by the "transit method," noting the tiny brightness dips caused when a planet crosses its host star's face from Kepler's perspective. This technique requires extremely precise pointing, an ability Kepler lost in May 2013 when the second of the observatory's four orientation-maintaining reaction wheels failed.

Related: Astronomers Observe Birth of an Alien Planet for First Time

But the Kepler team quickly figured out a way to keep the telescope stable, using solar radiation pressure as a sort of third wheel. That meant the spacecraft could eye different patches of the sky for around 80 days at a time to search for planets and other cosmic bodies and phenomena. That's what Kepler has been doing in its K2 mission, which NASA greenlit in May 2014.

Newly discovered planet could be closest match to Earth 0:28

Researchers had expressed hope that K2 could pick up some additional exoplanets and interesting structures in the sky. The extended mission has certainly delivered, spotting a few dozen confirmed planets, and now the tally will jump dramatically.

Related: Venus' Twin? New Earth-Sized Exoplanet GJ 1132b Found in Our Neighborhood

The first five K2 campaigns, which each looked at a different part of the sky, "have produced over 100 validated planets," Ian Crossfield, an astronomer at University of Arizona, said Tuesday during a presentation at the AAS meeting. "This is a validation of the whole K2 program's ability to find large numbers of true, bona fide planets."

This is a condensed version of a report from Space.com. Read the full report. Email Sarah Lewin at slewin@space.com or follow her @SarahExplains. Follow Space.com @Spacedotcom, Facebook and Google+.

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