Moon's Impact Craters Contain Remnants of Asteroids

A new study shows that approximately 25 percent of the moon's impact craters may actually retain substantial remnants of the asteroids that created them.

"Future studies of the moon's composition will have to show that exposed surface rocks really come from the moon and were not delivered by impacts, especially for unusual or exotic minerals," said co-author Jay Melosh of Purdue University.

Melosh and his colleagues, led by Zhong Yue of Purdue and the Chinese Academy of Sciences' Institute of Remote Sensing Applications in Beijing, used computer models to simulate the formation of lunar craters by asteroid impacts.

The researchers saw that one-quarter of space rock strikes on the moon is likely to occur at a velocity of 26,800 mph or less. 

According to the National Park Service, the width of a crater can accumulate remanats of asteroids as the body tends to collapse under the moon's gravity. 

These findings might explain the occurrence of minerals called spinels and olivines in the central peaks of large lunar craters.

Spinels and olivines are common in many asteroids, so it's possible that these and other minerals that scientists had assumed were indigenous to the moon were actually delivered via space rock strikes, researchers said.

"We cannot infer the deep composition of the moon from rocks in the centers of large craters without more care than has been used to date," Melosh said, according to SPACE.com via email, according to Fox News.

These finds could show that material blasted off Earth by colossal impacts long ago, which may have hit the moon at relatively slow velocities. 

"This raises the possibility of finding early Earth material, ejected by collisions billions of years ago, in massive deposits on the moon, and suggests yet another explanation for the spinels: that they are deposits derived from the Earth's upper mantle, emplaced long ago on to the moon and reworked," Erik Asphaug of Arizona State University, according to the same issue of Nature Geoscience.

"Even more provocative is the suggestion that we might someday find Earth's protobiological materials, no longer available on our geologically active and repeatedly recycled planet, in dry storage up in the lunar 'attic."

The findings of the new study are published online May 26 in the journal Nature Geoscience.