In DepthPlanetary Science

Rosetta ends 2-year comet mission with final descent

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Science  30 Sep 2016:
Vol. 353, Issue 6307, pp. 1482-1483
DOI: 10.1126/science.353.6307.1482

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Summary

All good things must come to an end, and so it will be on 30 September when the Rosetta spacecraft makes its planned soft landing onto the surface of comet 67P/Churyumov-Gerasimenko, the culmination of 2 years of close-up studies. Solar power has waned as 67P's orbit takes it and Rosetta farther from the sun, and so the mission team decided to go on a last data-gathering descent before the lights go out. This last data grab is a bonus after a mission that is already changing theorists' views about how comets and planets arose early in the solar system. Several Rosetta observations suggest that comets form not from jolting mergers of larger cometesimals, meters to kilometers across, but rather from the gentle coalescence of clouds of pebbles. And the detection of a single, feather-light, millimeter-sized particle—preserved since the birth of the solar system—should further the view of a gentle birth.