科学美国人60秒:Kepler Exoplanet Hunter Limps into Sunset

NASA’s best exoplanet hunter is limping into retirement. The Kepler space telescope has discovered more than 130 exoplanets in our galaxy. But it will seek new worlds no more.

Kepler relies on a set of four flywheels to stabilize its pointing and lock onto its target stars. The spacecraft was designed to tolerate one broken wheel, but not two. One gave out last year, and this May the really bad news arrived—a second wheel had failed. The Kepler team says they can’t revive the wheels. So astronomers will rely on ground-based telescopes to look for other worlds until NASA’s next planet hunter, the TESS satellite, launches around 2017.

But don’t send Kepler off into the sunset just yet. In an August 15th teleconference, NASA’s Bill Borucki, the mission’s principal investigator, noted that Kepler has loads of data that have yet to be fully searched for planets, including those Earth-like worlds that might host life: “So basically in the next two years, when we complete this analysis, we’ll be able to answer the question that inspired the Kepler mission: Are Earths common or rare in our galaxy?”

—John Matson