- This is what the Lunokhod rover released on the moon looked like in 1970. Nearly 40 years later, scientists have been able to locate the laser reflector, with the help of a telescope at Apache Point Observatory. (Courtesy of NASA)
A serendipitous discovery on the Moon can now be used to test Einstein’s theory of gravity.
Researchers at New Mexico State University’s Apache Point Observatory can now “laser ping” a once lost, but now found Russian robotic rover, the Lunokhod 1.
The robot carries a retroreflector, with the machinery last heard from way back in September 1971. Since that time, Lunokhod 1’s true whereabouts on the Moon remained unknown.
But in March, NASA’s Lunar Reconnaissance Orbiter took new high resolution pictures of the Moon’s surface – spotting the Russian rover. Once the Lunokhod 1 was located, scientists have also detected the lost reflector using Apache Point’s 3.5-meter telescope.
The Apache Point Observatory Lunar Laser-ranging Operation (APOLLO) is a special project, which is using the telescope to test Albert Einstein’s General Theory of Relativity. General relativity predicts how mass and energy give rise to gravitation and how objects should move under the influence of gravity.
Round-trip travel time
For Apache Point’s APOLLO project, physicists are using the telescope to bounce laser pulses off lunar reflectors on the moon to measure the round-trip travel time to within a few picoseconds and the instantaneous distance of the moon to within about a millimeter.
According to Kurt Anderson, director of Apache Point, once scientists had a better position of Lunokhod 1 from NASA’s Lunar Reconnaissance Orbiter images they were able to hit their target with laser pulses. Indeed, they were able to pinpoint its exact location to within 10 meters, he noted.
As for the fate of the decades-old reflector and rover, Anderson said there are no plans to retrieve the device. Since its position is now known, it can also be used to test Einstein’s theory of gravity.
“This was a serendipitous discovery,” Anderson said in a recent press statement. “It enables us to help the APOLLO project be more successful.”
By LD/CSE