Space junk craters. Dr Simon Green reflected in a foil sheet he is examining for impact craters. The sheet was part of an experiment carried on the Long Duration Exposure Facility (LDEF) satellite. This was launched on 7 April 1984 to monitor the environment in orbit, and was scheduled to be collected in February 1985. However, delays and the Challenger disaster allowed the LDEF to remain in orbit until it was collected in January 1990. This delay actually aided most of the experiments on board. Data from the impacts provides information about the damage they cause. This data is important in the planning of future missions, notably the proposed space station.