Researchers rediscovered long-lost data and used it to measure how quickly lunar dust piles up.
The moon-dust proved to be a huge issue during the 1969 Apollo moon landing. It stuck to everything it touched, caused some instruments to overheat, and even caused some astronauts to experience "hay-fever-like" symptoms, an American Geophysical Union news release reported.
Back in the 1970s researchers had conducted a study to see how fast lunar dust piled up, but the data was lost. After the data was rediscovered the researchers analyzed it, and found moon dust piles up extremely slowly.
The data suggests the dust piles up at a rate of only one millimeter every 1,000 years. This pace may seem sluggish, but researchers are concerned it could still be bad news for solar cells used in space exploration missions.
"You wouldn't see it; it's very thin indeed, "University of Western Australia Professor Brian O'Brien," a physicist who developed the experiment while working on the Apollo missions in the 1960s and now has led the new analysis," said. "But, as the Apollo astronauts learned, you can have a devil of a time overcoming even a small amount of dust."
Since the dust actually piles up faster than researchers had expected, the team believes the dust may have undiscovered methods of moving around.
The team gauged how quickly the dust moved by looking at the rate at which it layered onto a solar cell, which they determined to be 100 micrograms per square centimeter every year. This means an area about the size of a basketball court would collect a pound of dust annually.
The team also determined the dust could inhibit the performance of these solar cells.
"While solar cells have become hardier to radiation, nothing really has been done to make them more resistant to dust," O'Brien's colleague on the project Monique Hollick, who is also a researcher at the University of Western Australia, said. "That's going to be a problem for future lunar missions."
Researchers once believed the dust came solely from meteors and other types of impacts since the moon has little to no air movement.
"But that's not enough to account for what we measured," O'Brien said.
The researchers believe the movement could be caused by a phenomenon known as the "dust atmosphere." In this theory radiation from the Sun knocks some of the atoms in dust particles, causing a positive charge. On the moon's "nighttime side" electrons from the solar wind (the flow of energetic particles that come off the Sun) hits the particles and gives them a gentle negative charge.
The researchers believe the meeting of these dark and light regions could create electric forces which may have the power to levitate nearby dust.
"Something similar was reported by Apollo astronauts orbiting the Moon who looked out and saw dust glowing on the horizon," Hollick said.
