The Kepler space telescope has been peering into the heavens since 2009, carefully watching 150,000 alien suns in the search for potentially habitable worlds orbiting them. Data collected from the telescope has helped astronomers estimate that there are at least 17 billion (billion!) Earth-sized exoplanets in our galaxy.
This is amazing stuff, but Kepler has just suffered a serious hardware failure that puts its future in jeopardy. The failure is actually the second in a series of positioning hardware breakdowns, which is why it's so serious: the backup system that Kepler has been using to orient itself in space has stopped working.
The Kepler telescope uses a series of four reaction wheels to keep itself pointed at specific stars. The first of these failed on July 14, 2012. At the time, this was seen as a relatively minor problem, since the Kepler telescope really only needs three reaction wheels to stay aligned. Last night, however, a second reaction wheel failed, leaving the Kepler telescope unable to control where it's pointing.
NASA hasn't given up on their exoplanet hunter just yet. While the telescope's orbit around the Sun makes it impossible for astronauts to repair it (like they did with Hubble), NASA will nonetheless be searching for a workaround to the failure in the coming weeks, including trying to fix the old broken reaction wheel or seeing if they can successfully work out the kinks on the one that just quit. If all goes well, the Kepler telescope will be back up and searching for alien worlds after only a brief stint on the disabled list.
Fingers crossed, everyone, and we'll bring you an update as soon as NASA lets us know what's going on.