Space

NASA's Kepler telescope in trouble

NASA's Kepler space telescope has found more than 2,700 possible Earth-like planets. (NASA image)

Like an old man with arthritic joints, NASA's planet-seeking Kepler telescope can't move like it used to, and its most recent setback has put the four-year-old observatory into protective safe mode, potentially forever.

NASA officials announced on May 15 that the second of Kepler's four reaction wheels had failed. The first reaction wheel stopped working in July 2012. The wheels position and stabilize the telescope to point precisely at stars, and it needs at least three of the devices to be operational.

It the second time in the past month that NASA scientists found the telescope in thruster-controlled safe mode as a result of a malfunction in the reaction wheels. Although that mode minimizes fuel consumption, NASA officials said the craft only has enough fuel for a few months.

Officials are assessing their options, which include putting the craft into point rest state, which leaves Kepler to float around in space while scientists figure out whether they can fix the wheel, or using Kepler's operational thrusters and its two remaining wheels to turn it into a general data collector rather than having it zero in on specific stars.

Kepler orbits the sun some 40 million miles away, so astronauts cannot repair it in space.

Nevertheless, NASA officials remain optimistic. "We are not down and out," said Charles Sobeck, deputy project manager for Kepler at NASA's Ames Research Center. "The spacecraft is safe and stable. We'll proceed with our investigation."

An impressive legacy

Kepler was launched in March 2009 to seek Earth-like, potentially habitable planets. The $550 million telescope has spotted more than 2,700 potential exoplanets, with 132 confirmed as planets by ground-based telescopes so far. Scientists have said, however, that they expect more than 90 percent of Kepler's finds to be verified as planets.

In April, NASA scientists confirmed Kepler-62e and 62f as planets within the habitable zone of their solar system's parent star, Kepler-62 -- the first time Earth-sized planets were detected in a region of space scientists believe would be hospitable for life as we know it.

Kepler fulfilled its life expectancy in 2012, and though it might not seem old, among operational man-made objects in space, it is a veteran. And scientists still have massive amounts of planetary data from Kepler's observations to examine.