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Rosetta mission

Deployment of the Philae lander to comet 67PDeployment of the Philae lander to comet 67POn 12th November 2014, the Rosetta space probe launched its lander, called Philae, on to the comet 67P/Churyumov-Gerasimenko. The Philae lander had 10 instruments on board, including a drill capable of penetrating 20 centimetres into the ground and a radio transmitter. Rosetta released the lander at 08:35 GMT from a position of around 20 kilometres from the comet. It took 7 hours for Philae to descend to its target. The first landing was confirmed at around 16:05 GMT—but events did not quite turn out as expected.

Philae about to land on the cometPhilae about to land on the cometIt was discovered that harpoons designed to tether the washing-machine-sized Philae to the comet (which has extremely low gravity) had failed to fire. The craft "bounced", initially looping a kilometre or so back into space. It landed again after about two hours, before bouncing a second time—this time just for six minutes. It eventually came to rest on its side wedged between boulders and a cliff on the far side of a large crater. Any attempt to fire the harpoons at this stage might have risked sending Philae back into space.

Fears that the lander's solar panels might not receive enough sunlight in its new location to charge its batteries were realised at 00:36 GMT on 15th November, when contact was lost. It tweeted "I'm feeling a bit tired, did you get all my data? I might take a nap..." In fact, Philae managed to transmit all its data in the 57 hours of battery time available, including the detailed chemical composition of the comet itself. Its instruments also detected organic molecules in the comet's atmosphere.

The Philae lander is named after the obelisk discovered at Philae, Egypt. It has inscriptions in both ancient Egyptian hieroglyphs and Greek carved on its surface. Comparing its hieroglyphs with those on the Rosetta Stone helped scholars decipher ancient Egyptian writing in the early 19th century.

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