Planet-hunting Kepler turns six

Chuck Bednar for redOrbit.com – @BednarChuck

NASA’s planet-hunting Kepler spacecraft, which is responsible for discovering more than half of all known planets located beyond our solar system, celebrated its sixth birthday on Saturday, and we thought it would be a good time to take a look back its greatest achievements.

[ALL OF OUR STORIES RELATED TO THE KEPLER MISSION]

Kepler, which was named in honor of Renaissance astronomer Johannes Kepler (the man behind the laws of planetary motion), was launched on March 7, 2009. Its primary mission, which was originally supposed to last just 3 1/2 years, was to survey our region of the Milky Way galaxy in search of Earth-sized planets and smaller worlds located in or near the habitable zone.

According to Space.com, the $600 million mission searches for extrasolar planets by looking for tiny dips in brightness caused by such worlds when they cross the face of the host star. Using this technique, it has discovered more than 1,000 confirmed planets, with 3,100 additional candidates currently awaiting confirmation. Mission scientists anticipate that nearly 90 percent of them will wind up being verified through follow-up analysis or observations, the website added.

Kepler 186f

On April 17, 2014, astronomers using Kepler discovered the first Earth-size planet orbiting a star in the habitable zone of another star. That planet, Kepler-186f, proved that worlds approximately the same size as our planet orbit their stars in the range of distance within which it is possible for liquid water to form on the surface, officials from the US space agency explained.

“The discovery of Kepler-186f is a significant step toward finding worlds like our planet Earth,” said Paul Hertz, NASA’s Astrophysics Division director at the agency’s Washington DC-based headquarters. He added that future missions such as the James Webb Space Telescope will study nearby rocky exoplanets in order to “determine their composition and atmospheric conditions.”

HIP 116454b

Following the failure of its reaction wheel failed, it appeared as though Kepler would no longer be able to collect important scientific data. However, NASA and Ball Aerospace came up with a way to repurpose the spacecraft while allowing it to look for exoplanet candidates. In December 2014, it discovered the first exoplanet during the second phase of its mission, K2.

[OUR COVERAGE: NASA's Kepler finds new exoplanet]

The planet, HIP 116454b, was discovered by Andrew Vanderburg, a graduate student at the Harvard-Smithsonian Center for Astrophysics in Massachusetts, and his colleagues located the new planet in data collected during the K2 phase of the mission 10 months earlier.

The planet is located some 180 light-years from Earth in the direction of the constellation Pieces. HIP 116454b is 2.5 times the diameter of our planet and follows a close, nine-day orbit around a star that is both cooler and smaller than our sun, making it too hot to support life, NASA said.

“The Kepler mission showed us that planets larger in size than Earth and smaller than Neptune are common in the galaxy, yet they are absent in our solar system,” Steve Howell, Kepler/K2 project scientist at the Ames Research Center in Moffett Field, California said. “K2 is uniquely positioned to dramatically refine our understanding of these alien worlds and further define the boundary between rocky worlds like Earth and ice giants like Neptune.”

Still going strong

In January, scientists confirmed the 1,000th planet discovered by Kepler, one of eight candidates spotted by the planet-hunting telescope that included three worlds located in their sun’s habitable zones. Of those three, two of them are believed to be made of rock, the space agency noted.

[OUR COVERAGE: Kepler discovers 8 new Earth-like exoplanets]

“Each result from the planet-hunting Kepler mission’s treasure trove of data takes us another step closer to answering the question of whether we are alone in the Universe,” said John Grunsfeld, associate administrator at NASA’s Science Mission Directorate in Washington DC. “The Kepler team and its science community continue to produce impressive results with the data from this venerable explorer.”

Two of those newly validated planets, Kepler-438b and Kepler-442b, were said to be under 1.5 times the diameter of Earth. Kepler-438b, located 475 light-years away, is 12 percent larger than Earth and orbits its star once every 35.2 days. Kepler-442b,on the other hand, is 1,100 light-years away, 33 percent bigger than Earth, and orbits its star once every 112 days.

“With each new discovery of these small, possibly rocky worlds, our confidence strengthens in the determination of the true frequency of planets like Earth,” said Doug Caldwell, a SETI Institute Kepler scientist at Ames and one of the researchers that identified those planets. “The day is on the horizon when we’ll know how common temperate, rocky planets like Earth are.”

Since then, the now six-year-old telescope has discovered the first multi-planet system from the K2 phase of its mission, and followed that up by finding a planetary system of five small planets dating back to when the Milky Way galaxy was a just two billion years old. Stay tuned – only time will tell what discoveries Kepler will make between now and its seventh birthday!

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Source: http://www.redorbit.com/news/space/1113349729/planet-hunting-kepler-turns-six-031015/