In addition to this orbital reflector, there are five other larger reflectors on the Moon than were installed between 1969 and 1973 by astronauts during three Apollo missions of U.S and also by the unmanned vehicles of the Soviet Union Lunojod 1 and Lunojod 2, but their signals darkened over the years, perhaps due to dust.
The United States space agency launched the LRO probe into orbit in 2009, and since then astronomers fired the laser several times in an attempt to hit the tiny reflector, which consists of 12 mirrors in the shape of a cube corner. The goal of science was to point a laser beam at the reflector and measure the amount of time it took for the light to return, but it didn’t work for years because getting it right is difficult.
According to what NASA indicated, this successful experience made possible some important discoveries, as the slow separation of the Earth and its natural satellite: by an average of 3.8 centimeters per year. This growing gap is due to gravitational interactions between the two bodies.
As detailed by NASA, the light covers the 384 thousand kilometers of distance that separate the Earth and the Moon in about 2.5 seconds. Exact measurements allow science to calculate the distance between laser emitters on Earth and lunar reflectors with pinpoint precision.
“The precision of this single measurement has the potential to refine our understanding of gravity and the evolution of the solar system,” said Xiaoli Sun, scientific collaborator at the Goddard Geophysical and Astronomical Observatory in Greenbelt, who had helped design the reflector for the LRO.
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