A diagram of the Kepler spacecraft. Credit: NASA

Kepler glitch suspends NASA’s search for new planets

By Paul Sutherland
20 January 2013

(Sen) – NASA’s phenomenally successful planet hunter, the Kepler space telescope, has temporarily shut down operations after problems with part of the system that orientates it to keep it pointed at its stellar targets.

The spacecraft, currently more than 72 million km (45 million miles) away in its orbit around the Sun, has been put into a safe mode for ten days to allow one of its manoeuvring wheels to recover.

Kepler’s discoveries have boosted the number of confirmed exoplanets discovered transiting other stars to more than 850. But there are many more candidates awaiting confirmation. Another 461 were announced on January 7, at a gathering of the American Astronomical Society in California, bringing the total of those to 2,740.

“Increased friction over a prolonged period can lead to accumulated wear on the reaction wheel, and possible wheel failure” Roger Hunter, Kepler mission manager

Kepler has made all its finds in one relatively small area of the sky. Following launch in March 2009, it has been staring constantly at around 160,000 stars in one small region of the Milky Way in the constellations of Cygnus and Lyra. As it does so, it watches for fades in any star’s light that may indicate planets passing in front of it.

The spacecraft was launched with four so-called reaction wheels that spin to help keep the telescope pointing at its target fields of stars. One of these, reaction wheel No 2, failed in July 2012, leaving three to do the manoeuvres, including a quarterly roll to a new orientation.

Now reaction wheel No 4 has shown early indications that it might fail, prompting its NASA controllers to attempt some long-distance maintenance. They hope that by resting the wheels, their lubricant will spread to ease increased friction.

Read more: Kepler glitch suspends NASA's search for new planets — Sen.

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