The European Space Agency will launch in January 2003 a mission called “Rosetta” to visit a comet. This space-craft will rendezvous with comet Wirtanen, follow it on its way to the sun in a close orbit and observe the comet core from this position. As part of the mission, a small package is carried, the “Rosetta Lander”, which separates and lands softly on the surface of the comet, where it will carry out a sequence of scientific investigations.