sciencehabit writes from a report via Science Magazine: All good things must come to an end, and so it will be tomorrow 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 quiet birth. The report concludes: "A slew of instruments will keep gathering data as Rosetta approaches the surface at the speed of a gentle stroll. For team members whose instruments have already been turned off to conserve power, the ending is bittersweet -- but their work is far from over. Most instrument teams have only examined their own data, and are just now thinking about combining data sets. "We've just started collaborating with other teams," [Holger Sierks of the Max Planck Institute for Solar System Research in Gottingen, Germany, chief of Rosetta's main camera,] says. "This is the beginning of the story, not the end."