Goodbye Rosetta: Historic Space Mission To End With Controlled Crash Into Comet 67P

A few months ago, on February 12, 2016, the German Aerospace Agency (DLR) decided to say goodbye to the Philae lander. Now, the European Space Agency team that guided the Rosetta exploration is preparing for the last operation in which the spacecraft will crash into the comet 67P/Churyumov-Gerasimenko, which it has been circling for more than two years. The impact is told to be taking place on September 30th.

Rosetta is getting closer to the orbit of Jupiter, that means it'll eventually run short on solar power and also the bandwidth required to downlink necessary data to Earth. The early ideas, however, were to take Rosetta into hibernation as the comet headed towards aphelion and to awaken it again when the orbiter would reapproach the sun in four years' period. But the team finally decided against this as the aging spacecraft is not likely to survive another extended span in its hibernation.

During the coming weeks, Rosetta will be ordered to assume a series of looping elliptical orbits around the comet, terminating with a final "controlled crash landing" on the nucleus. The team hopes to get data from Rosetta until the very end. "Rosetta is going to continue the flow of current wealth of scientific data from 67P and will follow the comet's activity till its complete end," said Patrick Martin, Rosetta mission manager.

Achievements

The Rosetta story spans more than two decades since the very mission approval in 1993. Launched on the top of an Ariane 5 rocket on March 2, 2004, Rosetta cruised for an amazing 10 years and arrived in the orbit around the Comet 67P. Rosetta's discovery of organic molecules on 67P - the amino acid 'glycin' and phosphorus - supports the idea that material from comets could have played a major role in the appearance of life on Earth.

Rosetta has since then revealed the strange world of Comet 67P. One such amazing reveal is how dark the comet's surface is: with average reflectivity of just around 6½ %. The decision to end Rosetta's journey also represents the end of an era for the ESA researchers and all those scientists who spent decades on this amazing journey.

The spacecraft is going to descend in a more leisurely fashion than that of Philae, and scientists do expect to bring 'Rosetta's Orbiter Spectrometer for Ion and Neutral Analysis' (ROSINA) to study gases released from the still active comet. Similar applies for the OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) that will have a bird's eye view on its descent.

Landing the Rosetta is going to be tricky, with the starting changes to its trajectory already done in August. Scientists are still trying to figure out the exact location to set down Rosetta, but the descent is planned to be just 50 cm/s that is about half of Philae's landing speed.

"Planning this phase is far more complex than it was for Philae's landing," operations manager Sylvain Lodiot says. "The last weeks will be particularly challenging as we fly eccentric orbits around the comet -- this will be even riskier than the final descent itself."