NASA's Lunar Orbiter Successfully Pings India's Vikram Lander on Moon

The first successful transmission and reflection of a laser beam between a moving spacecraft and a stationary one on the lunar surface opens the door to precise location tracking for future lunar missions.

NASA's Lunar Reconnaissance Orbiter (LRO) successfully transmitted a laser beam to a small retroreflector on India's Vikram lander on the Moon, marking the first time a laser beam has been transmitted and reflected between a moving spacecraft and one stationed on the lunar surface.
The retroreflector, developed by NASA's Goddard Space Flight Center, is only 2 inches wide and contains eight quartz-corner-cube prisms set into a dome-shaped aluminum frame. It requires no power or maintenance and can reflect incoming light from any direction back to its source.
The technique of transmitting laser pulses towards an object and measuring how long it takes the light to bounce back is commonly used to track the locations of Earth-orbiting satellites from the ground. This new reverse application of the technique could be used by future astronauts on the Moon to determine precise locations.
It took the LRO eight attempts to make contact with the retroreflector on the Vikram lander due to the large gaps between the laser pulses emitted by the LRO's Lunar Orbiter Laser Altimeter (LOLA).
NASA plans to use more retroreflectors in future missions to the Moon, including the upcoming Artemis missions. The agency also has a retroreflector on Japan's SLIM, which recently landed on the Moon.