ScienceShot: Decades-Old Soviet Reflector Spotted on the Moon

It’s gotta be around here somewhere! No one had seen a laser reflector that Soviet scientists had left on the moon almost 40 years ago, despite years of searching. Turns out searchers had been looking kilometers in the wrong direction. On 22 April, a team of physicists finally saw an incredibly faint flash from the reflector, which was ferried across the lunar surface by the Lunokhod 1 rover (inset). The find comes thanks to NASA’s Lunar Reconnaissance Orbiter, which last month imaged a large area where the rover was reported to have been left. Then the researchers, led by Tom Murphy of the University of California, San Diego, could search one football-field-size area at a time until they got a reflection. Using their laser on the 3.5-meter telescope at the Apache Point Observatory in New Mexico like a radar, they immediately measured the distance from Earth to the reflector to within a centimeter. Now the team can eventually pin down the changing shape of the lunar orbit to the millimeter to help test Einstein’s theory of general relativity.