Higher Metal Concentration on Moon Provides New Clues to Origin

Ethen Kim Lieser

Science,

The fact that our moon could be richer in metals than the Earth challenges the hypothesis that portions of Earth’s mantle and crust were ejected into orbit to eventually form the moon.

According to the leading hypothesis regarding the formation of our natural satellite, an early Earth collided with another planet-sized body some 4.5 billion years ago, and the rubble from that devastating impact eventually coalesced into the moon.

Scientists have long believed that Earth’s upper crust, which is poor in metals, was impacted the most during this violent collision. Thus, one would think that the moon should also be lacking in metals.

However, a new study published in Earth and Planetary Science Letters suggests that the moon’s subsurface is richer in metals, like iron and titanium, than previously thought, which could challenge this popular theory on how our moon came to be.

Led by Essam Heggy, research scientist of electrical and computer engineering at the USC Viterbi School of Engineering and co-investigator of the Mini-RF instrument onboard NASA Lunar Reconnaissance Orbiter (LRO), the team members of the Miniature Radio Frequency (Mini-RF) instrument on the Lunar Reconnaissance Orbiter (LRO) mission used radar to image and characterize the fine lunar dust.

According to researchers, the fine dust located at the bottom of the moon’s craters is actually materials forced up from the lunar subsurface during meteor impacts. The team also discovered that larger and deeper craters possessed higher metal concentrations than smaller and shallower ones.

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

The fact that our moon could be richer in metals than the Earth challenges the hypothesis that portions of Earth’s mantle and crust were ejected into orbit to eventually form the moon.

“By improving our understanding of how much metal the moon’s subsurface actually has, scientists can constrain the ambiguities about how it has formed, how it is evolving and how it is contributing to maintaining habitability on Earth,” Heggy said in a release.

“Our solar system alone has over 200 moons—understanding the crucial role these moons play in the formation and evolution of the planets they orbit can give us deeper insights into how and where life conditions outside Earth might form and what it might look like.”

The team plans to continue carrying out additional radar observations on crater floors in the moon’s southern hemisphere to see if the same trends exist there.

Ethen Kim Lieser is a Minneapolis-based Science and Tech Editor who has held posts at Google, The Korea Herald, Lincoln Journal Star, AsianWeek and Arirang TV. Follow or contact him on LinkedIn.