Long-lost lunar rover successfully zapped with laser

Long-lost lunar rover successfully zapped with laser

Mirror mirror, on the moon, whose discovery has been a boon? The answer: a long-lost lunar rover. Now that we have a fix on its location, the rover's reflectivity could come in particularly handy for studying the moon's wobble.

Astronomers measure the moon's distance from Earth by bouncing laser beams off reflectors delivered to the surface by lunar missions. Three were left behind by Apollo astronauts and one is attached to the back of a Soviet-built robotic rover, Lunokhod 2.

Now, astronomers have managed to bounce laser light off another Soviet rover, Lunokhod 1, after a hiatus of nearly 40 years.

Lunokhod 1 landed on the moon in 1970 and last communicated with Earth by radio in 1971. It also has a reflector on its back but could not be targeted as its exact location was not known.

That changed in March when NASA's Lunar Reconnaissance Orbiter spotted Lunokhod 1. On 22 April, a team led by Tom Murphy of the University of California, San Diego, fired a laser at the new coordinates and got a reflected signal back. "We found it within minutes of our first attempt," Murphy says. "Once we knew where it was, it popped right out."

Lunokhod 1 is closer to the edge of the moon's Earth-facing side than any other reflector. That makes it useful for measuring slight wobbles in the moon's orientation, which could help reveal its internal structure. It could also allow precise tests of general relativity, which predicts how the moon should move in response to the gravity of Earth, the sun, and other solar system bodies.