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For the first time, scientists have successfully bounced off a laser from a mirror attached to a spacecraft orbiting the moon.

Reflecting the laser off the mirror on the lunar surface is an old trick. Astronauts walking on the moon first left reflective objects in 1969. And since then, researchers have emitted lasers from those reflectors to make precise measurements. about the distance between the moon and the Earth, using the speed of light and laser beam time. to return to Earth.

Sweeter than honey stronger than moonshine shirt, hoodie, tank top, sweater

But hitting a laser in orbit around the moon is a much more complicated task. The lunar reconnaissance orbiter (LRO) has been orbiting the moon with a mirror on its back since 2009. But almost a decade has passed without a successful laser beam. In an August 6 article in the Earth journal, Planets and Space, a group of researchers reported the first successful exposure to the laser: Twice on September 4, 2018 and twice more from August 23 to August 24, 2019, technicians at the Moon Laser Station (LLR) in Grasse, France, fired laser blasts at the LRO and saw the light return 2.5 seconds later there.
To ensure that the light that is reflected from the LRO returns in the direction it came from, the mirror on its back is more complicated than the mirror in your bathroom. Like the old mirrors on the surface of the Moon, it’s a “corner cube” – a series of three-dimensional mirrors, each shaped like the inside surface of one corner of the cube. When a laser is directed at it, the light will bounce back three times before the geometry of the mirror returns it in the exact direction it came from.

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An animation illustrates how the sheets that reflect the cube at an angle reflect light back in the direction it came from.
An animation illustrates how the sheets that reflect the cube at an angle reflect light back in the direction it came from. (Photo credit: V.pantaloni / Wikimedia Commons / CC BY 4.0)
Tracking the movement of the LRO over time is an exciting science project in its own right. However, the researchers wrote, these four successful laser contacts didn’t provide enough data to track that movement. The LRO is still moving too fast and too unpredictable to reliably hit the laser, and all four touchpoints are carried under the ideal conditions the researchers describe. The Moon, LRO and France are all perfectly lined up for improved laser exposure rates.