It might not be in the stars for humans to return to the moon anytime soon.
But NASA’s Lunar Reconnaissance Orbiter, launched last year in part to scout locations for a moon base, is proving that there’s still plenty it can do in the name of space exploration.
High-resolution LRO images have helped researchers track down the first successful robotic lunar rover, a U.S.S.R. craft known as Lunokhod 1.
The Soviet rover landed on the moon on November 17, 1970. The probe drove around for ten months, returning data on soil composition and lunar topography, before its signal was lost on September 14, 1971.
As can happen when you leave a broken vehicle roughly 239,000 miles (384,000 kilometers) from home, the exact location of Lunokhod 1 was lost to history.
Finding the rover wasn’t just an archaeological feat: Lunokhod 1 was carrying a reflector specifically designed to bounce back laser light beamed from Earth.
Knowing where to find the reflector will allow scientists today to aim lasers at the moon and get back precise readings on distance, lunar orientation, and tidal distortions.
Aside from adding proof that yes, in fact, we landed on the moon, accurate information from this laser ranging can in turn tell us about the moon’s interior composition and its long-term plans (our main satellite, btw, is slowly spiraling away from Earth at about 40 millimeters a year).
Combining laser data from several reflectors placed by the Apollo program and on Lunokhod 2 has been helping physicists study deviations in Einstein’s theory of general relativity.
That’s because lasers can measure the shape of the lunar orbit to within an accuracy of a millimeter, and GR predicts the lunar orbit to a similar degree of accuracy.
For 40 years Lunokhod 1 was like a missing piece of the puzzle.
“Lunokhod 1, by virtue of its location, would provide the best leverage for … producing an accurate estimate of the position of the center of the moon—which is of paramount importance in mapping out the orbit and putting Einstein’s gravity to a test,” UC San Diego physicist Tom Murphy said in a statement.
Murphy’s team had been on the hunt for Lunokhod 1 for years with no success, prompting fears that the rover has fallen into a ditch or parked itself so that the reflector was facing away from Earth.
Turns out, the LRO images proved, they were simply searching miles away from their target.
Let there be [an itteh-bitteh dot of] light.
“Not only now do we know that Lunokhod 1 is there, we also know that it is parked perfectly so that its reflector faces Earth,” Murphy said.
“In fact, the signal is so surprisingly strong that the rover could not be in anything but a level parking spot with its last commanded roll on the lunar surface deliberately oriented toward the Earth.”
In the spirit of international camaraderie that’s blossomed since the space race, Russian scientist and original Lunokhod analyst Ruslan Kuzmin wrote a special “thank you note” to NASA after seeing the new LRO pictures, which included high-res shots of the craft he worked with, Lunokhod 2.
“While looking at LROC images of the Lunokhod-2 rover, I felt a deep interior excitement due to the welled up memories of the earliest ‘pages’ of my science career,” he wrote.
“The LRO camera is without any doubt a really fantastic instrument that simultaneously brings our eyes close to the lunar surface, while reminding us of pioneering results from historical missions.”
Well said, Ruslan.
—Images courtesy NASA/GSFC/Arizona State University