We'll smash probe into comet 300 million miles away for kicks, er, sorry, ... for science

What a long, crazy ride it has been for ESA's Rosetta

Comet 67P/Churyumov-Gerasimenko

The European Space Agency (ESA) has set the date for the Rosetta probe's deathday and says that on September 30 the spacecraft will crash into the comet it has been orbiting for nearly two years.

With Comet 67P/Churyumov-Gerasimenko more than 300 million miles from Earth and heading out toward Jupiter, the spacecraft's solar panels are barely pulling in enough power to transmit data and power the probe's radiators.

So the astroboffins will bring it in a series of lower and lower orbits that will lead to its eventual demise somewhere on the surface. Rosetta earlier dropped a lander called Philae on 67P's surface.

"Planning this phase is in fact far more complex than it was for Philae's landing," said Sylvain Lodiot, ESA Rosetta spacecraft operations manager.

"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. The closer we get to the comet, the more influence its non-uniform gravity will have, requiring us to have more control on the trajectory, and therefore more maneuvers – our planning cycles will have to be executed on much shorter timescales."

Rosetta's companion craft, the lander Philae, is already on the comet's surface, but has produced very little science after a botched landing. The harpoons that were supposed to anchor the lander to the comet's surface failed and it bounced across the surface before landing at an angle that denied its solar panels vital sunlight.

It was possible to get some readings from the lander before its battery failed, but not much. So now Rosetta's going to take a second shot at getting details on the comet's surface.

The final orbital corrections will begin in August and the probe will swing closer and closer to the surface, taking high-resolution images and firing them back to Earth. Scientists also hope to get some information on the composition of the surface if the probe can be brought down softly enough, but that's very unlikely.

"We're trying to squeeze as many observations in as possible before we run out of solar power," said Matt Taylor, ESA Rosetta project scientist.

"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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