A look back at NASA's planet-pinpointing space 'scope
The space agency says the Kepler space telescope is having equipment issues. With the mission threatened, we look back at Kepler's mind-expanding search for Earth-like exoplanets.
NASA announced this week that a key piece of gear on its Kepler space telescope has run into trouble. And though the space agency hasn't given up on a jump-start, the mission may well be at risk.
It's already gone far beyond its planned duration, however, and presented us with many fascinating discoveries.
In this gallery, we take a look back at that mission -- at Kepler's intriguing quest to find Earth-like, life-friendly planets among the Milky Way's many stars.