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NASA Shot Lasers At The Moon For 50 Years, And One Finally Bounced Back
By Ell Ko, 21 Aug 2021
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Image via NASA
For the last decade, scientists at NASA have been taking aim with laser beams at a tiny reflector on the moon. Around 240,000 miles away, the panel—the size of a paperback novel—suddenly fired one back.
This reflector is mounted on the Lunar Reconnaissance Orbiter (LRO), a spacecraft that has been orbiting and studying the Moon since 2009. Its place was always meant to serve as a target, so scientists could test the reflecting power of panels previously left on the Moon around five decades ago.
Experiments like these have taken place ever since the Apollo era and are pretty simple: shoot a laser beam at the surface, and see how long it takes to come back.
By measuring the time it takes laser light to bounce back after reflected—an average of around 2.5 seconds—researchers can calculate the distance between the starting point on Earth and the reflectors on the Moon with an accuracy of just a few millimeters.
And the results have been no short of fascinating. NASA published its findings in the journal Earth, Planets, and Space, writing that through these measurements, it’s been able to learn that the Earth and the Moon are slowly drifting apart, moving about 1.5 inches further every year due to gravity.
A total of five reflecting panels are currently sitting on the Moon, three having been delivered by Apollo crews in the early 1970s and two in the form of Soviet rovers.
However, they’re all around 50 years old each, and researchers are speculating that dust may have kicked up and settled over them. As well as blocking light, the dust also insulates them, causing them to potentially overheat.
“Now that we’ve been collecting data for 50 years, we can see trends that we wouldn’t have been able to see otherwise,” states Erwan Mazarico, a planetary scientist from NASA’s Goddard Space Flight Center, in the news release. “Laser-ranging science is a long game,” he adds.
By using the reflector on the LRO and comparing the resultant discrepancies from the results gleaned from the quintet on the Moon, the team is hoping to be able to narrow down the reason why they’ve stopped functioning so well. Computer models will reveal if dust is responsible, or an unknown “something else.”
[via The Smithsonian Magazine, image via NASA]
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