Laser Ranging Retroreflector

Laser Ranging Retroreflector

The Apollo 11 Laser Ranging Retroreflector experiment on the Moon
Mission duration	Apollo 11: 54 years, 10 months, 2 days Apollo 14: 53 years, 3 months, 23 days Apollo 15: 52 years, 9 months, 23 days (in progress)
Spacecraft properties
Manufacturer	Arthur D. Little Inc PerkinElmer

The Laser Ranging Retroreflector (LRRR) is the first ever deployable lunar laser ranging experiment. It was carried on Apollo 11 as part of the Early Apollo Scientific Experiments Package, and on Apollo 14 and Apollo 15 as part of the Apollo Lunar Surface Experiments Package (ALSEP). The LRRR consists of a series of corner reflectors set within a panel. Laser beams sent from Earth are bounced off the retroreflector and the timing of the return signal can be used to measure the distance from the signal source to the reflector. The reflector was conceived by James E. Faller in 1961. The experiment's principal investigator was initially Carroll Alley of the University of Maryland who was eventually succeeded by Faller.