Today brought some incredibly sad news to planet hunters everywhere. The Kepler satellite, which has provided all the data which has fed our site since the beginning, has probably reached the end of its useful life, at least as far as hunting for planets goes.

Facts first. As reported elsewhere, Kepler’s fourth reaction wheel seems to have failed. The reaction wheels are what the spacecraft uses to point accurately, and with this failure Kepler’s down to only two, not the three needed to point precisely at its targets. Without three functioning reaction wheels, Kepler won’t be able to hold its gaze on the part of the sky that hold the stars that we’ve all become so familiar with over the last few years. There are still things to be tried – most of them variants on the tried and trusted ‘turn off and turn back on again’ methods – but the participants in today’s press conference didn’t seem very confident. The likely best case scenario involves Kepler being placed into a stable mode while those of us left on Earth spend the next few months contemplating what else it might be used for (budgets notwithstanding).

So where does this leave Planet Hunters? Bill Borucki – Kepler’s indefatigable principal investigator – was at pains during the press conference to stress that there is plenty of science left in the data that the spacecraft has already sent to Earth. He believes (and who are we to doubt) that Kepler already has enough information on hand to satisfy the critical science goal of determining what the odds of an Earth-sized planet are. There is a year or so of data that hasn’t been seriously reviewed by anyone, and much less than half of the data supplied has ever been viewed by Planet Hunters. In the long run, there are other data sets (the European COROT mission might be worth a look) and future missions (NASA’s TESS will follow where Kepler led, but looking for nearby planets).

Those discussions are for the days to come, though. For now, I want to pay tribute to the people behind the spacecraft. There’s a temptation at times like this to anthropomorize, to feel sorry for our plucky little planet hunter way up in space. Yet the truth is a mission like Kepler is what it is because of the blood, sweat and tears of hundreds of people, many of whom have dedicated literally years of their lives. I don’t know Bill Borucki well, but I first met him when I interviewed him for the BBC’s Sky at Night program. What struck me then, apart from his relaxed humility, was the tale he spun of year after year pitching what was to become Kepler only to be told that his ideas were unrealistic. Most people would have given up, but Bill and his team pressed on and as a result of that dedication were in the right place at the right time when the time came for an exoplanet mission to be picked.

The Kepler team are scattered across the US, and indeed across the world this evening. I hope many of them will be raising a glass to (what seems to be) the end of a job well done. Before we join them, the least we can do is go and look at some of their data they collected – after all, we still don’t know what’s lurking in the Kepler data displayed at Planet Hunters.

Chris