In DepthPlanetary Science

Philae probe makes bumpy touchdown on a comet

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Science  21 Nov 2014:
Vol. 346, Issue 6212, pp. 900-901
DOI: 10.1126/science.346.6212.900

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Until last week, space robots had landed on just six extraterrestrial worlds: the moon, Venus, Mars, Saturn's moon Titan, and the asteroids Eros and Itokawa. In successfully dropping the Philae lander to the surface of 67P/Churyumov-Gerasimenko on 12 November, Europe's Rosetta mission has added another locale to the list: a comet. The landing was not a perfect 10, however. Harpoons and reverse thrusters failed to fire, and Philae bounced its way into an awkward, shadowy spot. After 57 hours, it went into hibernation, its batteries exhausted. A much sought-after subsurface sample analysis did not occur in time. Yet scientists can bask in plenty of returned data and hope for a future resurrection, when more sunlight will fall on the lander. Meanwhile, the Rosetta orbiter will collect data for another 13 months. Already, it has made key measurements, including an exceptionally high deuterium-to-hydrogen ratio in the comet's halo of water. That indicates that comets like 67P were probably not responsible for delivering water to early Earth.

  • * in Darmstadt, Germany

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