Obituary: Kepler Spacecraft “Planet Hunter” 2009-2013

"...The ways by which men arrive at knowledge of the celestial things are hardly less wonderful than the nature of these things themselves," said pioneering astronomer Johannes Kepler in the 1600's. Kepler was the first astronomer to correctly lay out how the planets traveled around the Sun in a way that could be accurately predicted. His name went on to grace an orange spacecraft that had, until recently, been constantly awake in a search of starlight to find planets outside of our own solar system. Sadly, the Kepler spacecraft's search came to an end in May 2013. And on August 15th, NASA announced that it was ending its attempts to bring the spacecraft back into working order.

The Kepler spacecraft was finally crippled by the loss of a second gyroscope-like "reaction-wheel"-a mechanism that helped accurately point the craft at its objectives. It needed at least three out of its four original wheels to continue collecting data, and after May it was left with only two. But though it has expired in its original purpose, Kepler leaves behind a loving family of hundreds of astronomers and an adoring public.

The spacecraft was NASA's extra-solar planet hunter. Launched in 2009, it was taken to space by a Delta II rocket launched from Cape Canaveral, Florida. The first of its kind, the spacecraft successfully confirmed 136 planets while hunting. The way it found those planets was relatively simple: It monitored a rich star field for the dimming of starlight when a planet would orbit in front of its respective sun.

Specifically, the Kepler spacecraft would read the light from stars near the Cygnus and Lyra constellations-it stared at over 100,000 stars simultaneously during its tenure.

Not only did Kepler confirm hundreds of planets outside our own solar system-so called "exoplanets"-it collected evidence suggestive of thousands of planets not yet confirmed. "Using NASA's planet-hunting Kepler spacecraft," states a graphic at NASA's Kepler site, "...astronomers have discovered 2,740 planet candidates orbiting 2,036 other suns in a search for Earth-sized worlds." Kepler might be closing its eyes, but there is still work to be done. The surplus of unanalyzed data from this cunning hunter is surely full of surprises.

Of the unconfirmed planets, one may have the possibility of being a "Goldilocks Planet"-an Earth-like planet that may have the conditions to support life. It would need to have a distance from its star that would render the planet's surface not too hot or too cold-just right. Rory Barnes, research scientist and the lead author of a related study out of the University Of Washington, talked about three such potential Goldilocks planets on Science Friday in June.

Besides the Goldilocks planets, Kepler is also revealing wondrously dangerous ones. MIT released a study on Monday claiming it has culled data to reveal a planet that makes its orbit in 8.5 hours. Kepler 78b, as it is being called, is so close to its sun that its surface temperature exceeds 5000 degrees Fahrenheit. Kepler 78b is seemingly covered in an ocean of lava.

NASA is now looking at what the spacecraft can be used for in its diminished capacity. A second Kepler Science Conference will be held November 4^th-8^th at the NASA AMES Research Center where much of the data that the craft collected will be reviewed. What other fascinating finds are hiding in all the stars Kepler diligently stared at?

We are indebted to Kepler; the spacecraft showed us that there are many different planets in our galaxy that we did not know existed-and many more than Kepler himself ever dreamed of-planets that hold mysteries beyond our own. The craft is now a forefather of space discovery like Armstrong, Aldrin, and Copernicus. We will miss your presence Kepler, may you find great new purpose beyond the rim of this now richer world.

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Image Credit:

Artist's concept shows the Kepler spacecraft by NASA/Ames/JPL-Caltech

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