Lunar Litter Used to Reveal Moon's Love Number

nickynicky9doors writes: "NASA's Jet Propulsion Laboratory has an article on the Moon's Love number. A planet's Love Number is a measure of ... 'how much a planet's surface and interior move in response to the gravitational pull of nearby bodies.' To measure the Moon's Love Number Laser pulses are directed off discarded retroreflectors leftover from missions thirty years ago."