Science & Technology: Lander: "Lander
Introduction
The 100 kg Rosetta Lander will be the first spacecraft ever to make a soft landing on the surface of a comet nucleus. The Lander is provided by a European consortium under the leadership of the German Aerospace Research Institute (DLR). Other members of the consortium are ESA, CNES and institutes from Austria, Finland, France, Hungary, Ireland, Italy and the UK.
The box-shaped Lander is carried in piggyback fashion on the side of the Orbiter until it arrives at Comet 67P/Churyumov-Gerasimenko. Once the Orbiter is aligned correctly, the ground station commands the Lander to self-eject from the main spacecraft and unfold its three legs, ready for a gentle touch down at the end of the ballistic descent. On landing, the legs damp out most of the kinetic energy to reduce the chance of bouncing, and they can rotate, lift or tilt to return the Lander to an upright position.
Immediately after touchdown, a harpoon is fired to anchor the Lander to the ground and prevent it escaping from the comet's extremely weak gravity. The minimum mission target for scientific observations is one week, but surface operations may continue for many months."

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