An ocean of molten rock covered the moon's entire surface early in its history, which then cooled over millions of years, but a new analysis suggests it wasn't the last time the Moon's surface was melted on a massive scale, planetary scientists from Brown University said.
Data from NASA's Lunar Orbiter Laser Altimeter shows an impact event that formed the Orientale basin on the Moon's western edge and far side produced a sea of melted rock 220 miles across and at least six miles deep, they said.
Similar seas of impact melt were probably present at various times in at least 30 other large impact basins on the moon, and the amount of rock formed in melt seas is far from trivial, researchers said.
Brown graduate student William Vaughan and his colleagues said they estimate impacts forming the Moon's 30 large basins produced almost 240,000 cubic miles of melt, enough to make up 5 percent of the Moon's crust.
"This work adds the concept of impact melt magma seas to the lexicon of lunar rock-forming processes," Brown planetary geologist James W. Head III said.