Tagged: National Aeronautics and Space Administration (NASA)

The planet-hunting career of NASA's Kepler spacecraft might be near its end.

Astronomers said Wednesday that a reaction wheel that keeps the orbiting telescope pointed at tiny, distant patches of sky to look for Earth-like planets has failed. If they can't fix it, Kepler will be relegated to a less prestigious mission, directing its gaze much closer to home in a search for so-called "near-Earth objects," i.e., meteors and asteroids.

Two astronauts went on a last-minute spacewalk Saturday to replace a pump suspected of being the source of a serious ammonia leak.

It was unclear what caused the ammonia leak, NASA spokesman Rob Navias said, "but the installation of this spare pump package — at least at the moment — seems to have done the trick."

NASA officials called the spacewalk a success, but said it would take time to see if the leak was indeed stopped. Engineers will review photos the astronauts took at the site.