Faulty steering wheel jeopardizes Kepler space telescope


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A faulty steering apparatus may bring an early end to NASA?s Kepler space telescope, a $600 million tool in the space agency?s quest for life elsewhere in the universe.

Kepler is the first NASA mission capable of finding Earth-size planets in or near the habitable zone, the range of distance from a star where the surface temperature of an orbiting planet might be suitable for liquid water. Launched in 2009, it has discovered thousands of such planets, including a pair just 1,200 light years away.

Called Kepler-62-e and Kepler-62-f, the news of their discovery came about one month ago. But yesterday, Kepler?s mission ran into trouble.

Kepler is powered by four solar panels, and the spacecraft must execute a 90-degree roll every 3 months to reposition the solar panels to face the sun while keeping its eye precisely aimed. Kepler launched with four wheels to control that motion -- and one of them failed last year.

The space telescope was placed in ?thruster-controlled safe mode? yesterday, said NASA spokesman J.D. Harrington.

?Our normal response to that ? is to command it back to wheels. We did that and we initially saw some movement of the wheel,? explaied Charles Sobeck, deputy project manager with Ames Research Center. That movement quickly ground to a halt, he said.

?This is indicative of an internal failure within the wheel.?

Kepler will continue working for the next few months, and NASA will look to reduce fuel consumption during that time to extend the lifespan of the spacecraft.

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Failure of NASA's Kepler telescope puts search for another Earth in peril

Telescope orbiting the Sun has lost part of its stabilising system, making it too inaccurate to hunt for another Earth

Nasa-sketch-of-Kepler-22b-010.jpg

Nasa artist's impression of Kepler-22b, one of the planets spotted by the telescope that may be able to support life. Photograph: Nasa/Rex features

Nasa's hunt for other planets that could harbour life faces a setback: its Kepler space telescope is broken and, since it is in orbit around the Sun, may prove impossible to fix.

The failure of stabilising systems on the spacecraft could mean an end to the $600m mission's search, although Kepler has already outlived official expectations and the space agency is not yet ready to call it quits. The telescope has discovered scores of planets but only two so far that show strong signs of being habitable.

"I wouldn't call Kepler down and out just yet," said Nasa sciences chief John Grunsfeld.

Nasa said Kepler had lost two out of four wheels that control its orientation in space, meaning it can't point at stars with the same precision.

In orbit around the sun, 40m miles (65m kilometres) from Earth, Kepler is too far away to send astronauts on a repair mission like Nasa did to the Hubble telescope. Engineers on the ground are trying to restart one of Kepler's faulty wheels or find a workaround. The telescope could be used for other purposes if it can no longer track down planets.

Kepler was launched in 2009 in search of Earth-like planets. So far it has confirmed 132 planets and spotted more than 2,700 potential ones. Its mission was supposed to be over by now but in 2012 Nasa agreed to keep it running through 2016 at a cost of about $20m a year.

In April Kepler scientists announced the discovery of a distant duo that seems ideal for some sort of life to flourish. The other planets found by Kepler haven't fitted all the criteria that would make them right for life of any kind, from microbes to humanoids.

While ground telescopes can hunt for planets outside our solar system, Kepler is much more advanced and is the first space mission dedicated to that goal.

For the past four years Kepler has focused its telescope on a faraway patch of the Milky Way where there are more than 150,000 suns, recording slight dips in brightness that give away a planet passing in front of a star.

Now "we can't point where we need to point. We can't gather data," deputy project manager Charles Sobeck said.

Scientists said there was a backlog of data they still needed to analyse even if Kepler stopped looking for planets. "I think the most interesting, exciting discoveries are coming in the next two years. The mission is not over," said chief scientist William Borucki at the Nasa Ames research centre in northern California, which manages the mission.

Scientists who have no role in Kepler mourned the news, saying the spacecraft may not be able to determine how many Earth-size planets are in the "Goldilocks zone" where it's not too hot or too cold for water to exist in liquid form on the surface. They praised the data collected by Kepler so far but said several more years of observations were needed to analyse it all.

"This is one of the saddest days in my life. A crippled Kepler may be able to do other things but it cannot do the one thing it was designed to do," said Alan Boss of the Carnegie Institution of Washington.

In 2017 Nasa plans to launch Tess ? the Transiting Exoplanet Survey Satellite ? designed to search for planets around nearby stars.

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If we still had shuttles coming and going we could mount a rescue mission. But we don't.

Kepler is much too far away for rescue.

In orbit around the sun, 40 million miles from Earth, Kepler is too far away to send astronauts on a repair mission like the way Grunsfeld and others fixed a mirror on the Hubble Space Telescope.

http://articles.washingtonpost.com/2013-05-15/national/39277067_1_william-borucki-kepler-scientists-habitable-planets

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