Design
The lander is designed to touch down on the comet’s surface after detaching itself from the main spacecraft body and “falling” towards the comet along a ballistic trajectory. It also will deploy harpoons to anchor itself to the surface, and the legs are designed to dampen the initial impact to avoid bouncing. Communications with Earth will use the orbiter spacecraft as a relay station to reduce the electrical power needed. The mission duration on the surface is planned to be at least one week, but an extended mission lasting months is possible.
The main structure of the lander is made from carbon fiber, shaped into a plate maintaining mechanical stability, a platform for the science instruments, and a hexagonal “sandwich” to connect all the parts. The total mass is about 100 kg. Its "hood" is covered with solar cells for power generation.
It was originally planned to rendezvous with the comet 46P/Wirtanen. A failure of the Ariane 5 launch vehicle necessitated a change in target to the comet 67P/Churyumov-Gerasimenko. The larger comet mass and the resulting increased impact velocity made modification of the landing gear necessary. Besides the changes made to launch time and target, the mission profile remained unchanged.
Read more about this topic: Philae (spacecraft)
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