An experiment to count impacts made by meteoroid and space debris while in space. MAP was flown on NASA's Long-Duration Exposure Facility satellite that was launched in April 1984 by the space shuttle Challenger. It was retrieved in January 1990 by Columbia. MAP consisted of thin foil layers that were pointed in five directions. During their 69 months in space, the foils received 2 342 perforations. Most came from ‘unbound particles’ of extraterrestrial origin rather than ‘bound particles’ from the Earth orbital area.