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In 1970, the Soviet¹ Union put a laser reflector on the moon, carried by a rover. A few months later, it disappeared. Some speculated that the rover had fallen into a crater² or parked in such a way as to render the reflector inaccessible³. Now after 40 years on the lunar surface, the reflector has been found.

A team at U.C. San Diego has been searching for it. Earlier this year, NASA’(National Aeronautics⁴ and Space Administration）lunar reconnaissance orbiter camera provided images of the regional landing area. A sunlit speck⁵ miles from where the team was looking, turned out to be the rover and reflector. The San Diego team was quickly able to pinpoint⁶ the reflector's location to within 10 meters. Scientists send laser pulses to the moon and measured signals that bounce back from three reflectors left by Apollo astronauts, along with another Soviet one. This information helps track the moon's position and orbit. And the researchers say that the rediscovered Russian reflector is particularly useful for studying in the moon liquid core and testing ideas about gravity. Says team leader Tom Murphy of the reflector, “It’s got a lot to say after almost 40 years of silence."