On Nov. 12, 2014, the European Space Agency's Rosetta orbiter dropped a little lander named Philae down onto the surface of comet 67P/Churyumov-Gerasimenko. The robot made history as the first man-made object to have a controlled landing on a comet and was meant to help us uncover some of the secrets of our early solar system from 67P's icy core. And it did — for two days.
A bumpy landing put Philae in the shade, rendering its solar panels useless. Scientists worked frantically with the bot's reserve battery power, doing improvised science experiments to glean as much data as possible from a lander whose exact whereabouts remained unknown. But once its 60 hours of battery life ran out, the lander went silent.
Scientists hoped that as the comet reached perihelion — its closest orbital approach of the sun — the increase in light would give Philae a charge. Rosetta listened for a signal, even as the chances grew more and more slim. As of February of this year, with the sun in 67P's rearview mirror, hearing from Philae again became virtually impossible.
But until Wednesday morning, Rosetta kept listening.
"Today communication with Philae was stopped," Andreas Schütz, media spokesman of German space agency DLR, told the AFP on Wednesday.
At around 5 a.m. Eastern time, scientists switched off Rosetta's Electrical Support System Processor Unit (ESS), which was used to communicate with the lander. On Sept. 30, just over two years after entering orbit around 67P, Rosetta will crash onto the comet's surface and complete its mission. Because Rosetta will have very little solar power by that time — it's already over 320 million miles from the sun — the mission team needs to start shutting down unnecessary systems. Four months after the last real chance of hearing from Philae, they've decided it's finally time to stop listening.
Nature reports that the mission team isn't too emotional over the official shutdown. They'd given up on Philae's long odds back in February. Instead, they're saving their tears for September — when the Rosetta orbiter crashes down to join its long lost pal.