It’s alive! After suffering a critical injury last year, NASA’s Kepler space telescope has just observed an exoplanet for the first time in months. The Jupiter-sized world is not a new discovery – it was found by another telescope – but spotting it again with Kepler is solid evidence that, following a few modifications, the famed planet-hunter is ready to get back to work.

Launched in 2009, Kepler was designed to see planetary transits – the tiny dips in starlight when a planet passes in front of its star, from Earth’s perspective. Over four years the mission collected almost 250 confirmed planets and thousands more candidates, boosting our confidence that the galaxy is brimming with alien worlds.

But observations ground to a halt last year, when mechanical failures killed Kepler’s precision steering system and ruined its ability to hold steady enough to see transits. At least, until now. At a meeting in November last year, the Kepler team announced the K2 mission, which would use the radiation pressure from sunlight to hold the craft steady for up to 75 days at a time.

During a test run in January, the K2 team nabbed their first planet: a previously identified gas giant called WASP-28b. Seeing a clear signal is verification that the Kepler’s new mission concept will work as planned.


“It’s a lovely planet transit. If you were in this field you’d look at this and right away say, ‘Oh, of course it’s a planet!'” says project scientist Steve Howell. “It’s very exciting.”

Younger quarry

WASP-28b is about the size of Jupiter and is in a very tight orbit around its star, with a year that lasts just 3.4 Earth days. Unfortunately, K2 will not be able to carry on with Kepler’s original quest to find habitable Earth-sized planets around sun-like stars. To confirm that a planet is real, Kepler needed to see it transit three times, meaning true Earth twins would take about three years to confirm. The modified space telescope won’t be able to maintain its lock on a star for that long.

But the K2 mission will be able to collect data on very young stars and search for planets or planet-forming discs around them. “This will be a window into both star formation and planet formation,” says Howell.

For now K2 is operating on funding reserves from the main Kepler mission, and the team is waiting on approval for NASA funding for another two years. That decision is expected by the end of May. In the meantime, the team is ploughing ahead. The first official science campaign will start on 1 March – and the team has already received requests to observe 110,000 target stars.

“For us that’s great news, not because we can do all of that, but because it’s a sign of the interest of the community,” says Howell.