A retroreflector laser, originally placed on the Moon by the Soviet probe Luna 17 in 1970, has been rediscovered after nearly four decades of being lost to history. This device, part of a collaborative effort between France and the Soviet Union, was installed on the Lunokhod 1 rover—a lunar rover that landed on the Moon’s Sea of Rain on November 17, 1970. The rover operated for 11 lunar days, traveling about 10.5 kilometers before its power source, a radioactive polonium isotope, ran out in September 1971, causing it to stop functioning. After its shutdown, the exact location of the rover and its retroreflector was lost, buried in Soviet archives. The rediscovery came in 2010, when high-resolution satellite images from NASA’s Lunar Reconnaissance Orbiter (LRO) revealed the rover’s location with an accuracy of about 100 meters. This breakthrough allowed scientists to locate the retroreflector, which had been silent for nearly 40 years. The Apache Point Observatory Lunar Laser-ranging Operation (APOLLO) team, led by physicist Tom Murphy, successfully aimed a laser at the device on April 22, 2010. The team detected a signal that was four to five times stronger than signals from other lunar retroreflectors, likely due to the mirror’s better preservation. Its location in a higher latitude may have protected it from the accumulation of lunar dust, which often degrades such instruments over time. The retroreflector is now an active part of the international lunar laser ranging program, which uses these devices to measure the distance between the Earth and the Moon with extreme precision. This data helps refine our understanding of the Earth-Moon system and test Einstein’s theory of general relativity. Despite the dissolution of the Soviet Union and the scattering of its archives, the retroreflector continues to function, responding to laser pulses from observatories on Earth. Its rediscovery highlights the enduring value of early space missions and the importance of international collaboration in scientific research.