NASA's LRO finds larger meteors dug up more metal from Moon's subsurface

Scientists searching for ice in the Moon’s polar craters found evidence that more metal lurks beneath the lunar surface than they expected.

Researchers using the Miniature Radio Frequency (Mini-RF) instrument on NASA’s Lunar Reconnaissance Orbiter (LRO) spacecraft found little evidence of metals in the dust in small craters, NASA said, the agency’s LRO website reported. But by using the Mini-RF to measure the dielectric constant within lunar soil on different sized craters’ floors in the Moon’s northern hemisphere, they saw that the property rose with the size of the crater.

They reasoned that since larger craters dig deeper into the Moon’s subsurface, that increase could come from the bigger meteors excavating iron and titanium oxides farther below the surface. The concentration of the metal minerals is linked to dielectric properties, NASA said on the LRO website.

A comparison of the Mini-RF images with metal oxide maps from NASA’s Lunar Prospector, the LRO Wide-Angle Camera and Japan’s Kaguya mission bore this out. Larger amounts of metals were found in the larger craters, which suggest that depths below 0.3 miles have more iron and titanium oxides than from upper levels of the lunar subsurface, the LRO website reported.

“The LRO mission and its radar instrument continue to surprise us with new insights about the origins and complexity of our nearest neighbor,” Wes Patterson, Mini-RF principal investigator from the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland, and a study co-author, said, the LRO website reported.

Researchers see evidence that a collision between Earth and a Mars-sized protoplanet created the Moon. Finding that rocks in the lunar highlands only have small amounts of metal-bearing minerals relative to Earth seems to point to the impact happening before the Earth had its core, mantle and crust differentiated. But the amount of metal in the Moon’s maria is richer than many rocks on Earth.

The discovery using the Mini-RF seems to suggest a solution by showing more metal beneath the subsurface, the LRO website reported.