Mark your calendars and stock up on tissues: On Sept. 30, the European Space Agency's Rosetta orbiter will crash into a cometary cemetery. After two years circling Comet 67P/Churyumov-Gerasimenko and doing some great science, the spacecraft will be no more.

Rosetta is perhaps most famous for being the mothership of Philae, a robot that made history as the first artificial object to land on the surface of a comet. Philae captured global attention — and stole all of our hearts — when a bumpy touchdown led to her premature demise. As recently as a few months ago, ESA scientists attempted to regain contact with Philae — but now it's safe to say that the lander is lost, having only gotten in a few precious hours of scientific exploration before failing.

Rosetta has been plenty busy without the help of her lost lander, but even the most successful mission must eventually draw to a close. Even ignoring age and decay — Rosetta has now been in space for some 12 years — the spacecraft's ever-increasing distance from the sun will soon keep it from absorbing enough solar power to remain functional.

The orbiter was once put into hibernation to save its life as it zipped away from the sun's powerful rays, but this was back when it was still en route to the comet it now orbits. Now its trajectory is tied to the comet's — and that means it's going to get very, very far away before it comes back to the sun's warm embrace. Since it's unlikely that the spacecraft would survive this journey, even while hibernating, it's going to bite the dust on Sept. 30.

"Planning this phase is in fact far more complex than it was for Philae's landing," Sylvain Lodiot, ESA Rosetta spacecraft operations manager, said in a statement. In the weeks leading up to the final crash in September, Rosetta will be brought closer and closer to Comet 67P. The closer it gets, the more the spacecraft will be influenced by the comet's irregular gravitational pull.

"The last six weeks will be particularly challenging as we fly eccentric orbits around the comet — in many ways this will be even riskier than the final descent itself," Lodiot said.

The orbiter will switch off many of its instruments before the crash, and it's likely that the antenna it uses to transmit data back to Earth will end up pointed in the wrong direction — so the impact will mark the end of our communication with the spacecraft. But the mission is far from over.

"We're trying to squeeze as many observations in as possible before we run out of solar power," project scientist Matt Taylor said in a statement. "30 September will mark the end of spacecraft operations, but the beginning of the phase where the full focus of the teams will be on science. That is what the Rosetta mission was launched for and we have years of work ahead of us, thoroughly analyzing its data."

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