New observations have raised the question, is the Moon drifting away from Earth?
Over several decades scientists have bounced laser beams off reflector panels on the Moon, about 240,000 miles away from Earth. Researchers can measure the distance by recording how long it takes the laser light to return to Earth.
The data now reveals the Earth and Moon are slowly drifting apart at 1.5 inches per year, about the rate fingernails grow.
“Now that we’ve been collecting data for 50 years, we can see trends that we wouldn’t have been able to see otherwise,” said Erwan Mazarico, a planetary scientist from NASA’s Goddard Space Flight Center.
Two out of the five reflecting panels on the Moon were delivered by Apollo 11 and 14 crews in 1969 and 1971 and are each made of 100 mirrors known as “corner cubes.” These panels can reflect light back to any direction from which it comes. Panels were subsequently dropped off by Apollo 15 astronauts in 1971 and two more panels by Soviet robotic rovers in 1970 and 1973. Using this network of panels, the reflectors are the last remaining science experiment from the Apollo era still active on the lunar surface.
But lately they have a diminished return, about a tenth of the expected signal, which may be the result of space dust. Scientists believe the dust may have settled on the reflectors over the decades as the lunar surface gets pummeled by micrometeorite impacts. The debris could be restricting light, causing the system to overheat and reduce its efficiency and accuracy.
Scientist hope to use the Lunar Reconnaissance Orbiter (LRO) reflector to verify if the dust particles are blocking the light from reaching the mirrors by cross-referencing it with the lunar surface panels.
The LRO has been studying the Moon from orbit since 2009, according to Business Standard. The reflectors on the spacecraft were intended to test and verify the power of the lunar surface panels left by Apollo missions nearly half a century ago.
The laser experiments conducted on the Moon have been going on for quite some time now beginning with astronaut Neil Armstrong and Buzz Aldrin in 1969. There are four telescopes in observatories in New Mexico, France, Italy, and Germany that fire lasers, measuring the time that it takes to bounce off and return to Earth. This worldwide network of reflectors helps measure distance, orbit, rotation and the orientation of the Moon over the years, which are highly critical for spacecraft landing and orbital missions around Earth’s primary satellite.
The beams also help scientists understand the natural phenomenon of tides, providing useful information for sea-going vessels navigating the oceans, ports and waterways. Contrary to popular belief the tide is highest not when the Moon is overhead, but hours later after it reaches its apex. The Moon itself also expands and contracts. According to NASA, “the positions of the reflecting arrays have varied as much as six inches (15 centimeters) up and down each month as the Moon flexes.”
The laser research also revealed the Moon has a partially liquid core as scientists continue to study if the solid material there would have energized the now-defunct magnetic field. “The precision of this one measurement has the potential to refine our understanding of gravity and the evolution of the solar system,” said Xiaoli Sun, a Goddard planetary scientist who helped design LRO’s reflector.