While studying the ice formations in polar lunar craters, scientists have made a startling discovery about the Moon. As per the findings, the Earth¡¯s natural satellite might be richer in metals and minerals like iron and titanium than previously assumed.
The new study has been conducted by team members of the Miniature Radio Frequency (Mini-RF) instrument on NASA¡¯s Lunar Reconnaissance Orbiter (LRO) spacecraft and has been published in Earth and Planetary Science Letters on July 1.
Through the evidently mineral-rich subsurface of the Moon, the study sheds more light on the connection between Earth and the Moon, possibly revealing answers to questions around its formation.
The researchers used Mini-RF to measure the dielectric constant on lunar soil. Dielectric constant is an electrical property that measures the relative ability of a material to transmit electric fields in comparison with the vacuum of space.
The researchers were using the technique to locate ice formations in the crater shadows on the northern hemisphere of the moon. The team, however, noticed an increase in the dielectric constant as the crater size increased.
For 2 to 5 kilometers wide craters, the dielectric constant of the material steadily increased with size. Craters between 5 to 20 kilometers wide, however, showed it to be constant.
¡°It was a surprising relationship that we had no reason to believe would exist,¡± said Essam Heggy, as mentioned in a NASA report. Heggy is the co investigator of the Mini-RF experiments from the University of Southern California in Los Angeles and lead author of the published paper.
Dielectric properties are directly proportionate to the concentration of metal minerals. Based on this fact, the team came up with a possibility that the increasing dielectric constant on the larger craters could be because of meteors excavating iron and titanium oxides lying below the Moon¡¯s surface.
Since the larger craters were formed by bigger meteors that dug deeper into the surface, the minerals are possibly located deeper into the Moon¡¯s soil.
The hypothesis suggested that the Moon is devoid of such minerals only for a few hundred meters below the surface. Deeper down the Moon¡¯s surface ¡°there¡¯s a steady increase to a rich and unexpected bonanza.¡±
To confirm the theory, scientists compared crater floor radar images from Mini-RF with metal oxide maps from the LRO Wide-Angle Camera, Japan¡¯s Kaguya mission and NASA¡¯s Lunar Prospector spacecraft. The findings matched with the suggestions from the theory.
¡°The larger craters, with their increased dielectric material, were also richer in metals, suggesting that more iron and titanium oxides had been excavated from the depths of 0.3 to 1 mile (0.5 to 2 kilometers) than from the upper 0.1 to 0.3 miles (0.2 to 0.5 kilometers) of the lunar subsurface,¡± points out the report.
The startling discovery rekindles the interest in Moon¡¯s history. ¡°This exciting result from Mini-RF shows that even after 11 years in operation at the Moon, we are still making new discoveries about the ancient history of our nearest neighbor,¡± said Noah Petro, the LRO project scientist at NASA¡¯s Goddard Space Flight Center in Greenbelt, Maryland.?
The results are in line with recent evidence from NASA¡¯s Gravity Recovery and Interior Laboratory (GRAIL) mission. The evidence similarly suggested a ¡°significant mass of dense material exists just a few tens to hundreds of kilometers beneath the Moon¡¯s enormous.¡± This indicates that such metal minerals are not uniformly distributed in the Moon¡¯s subsurface.
The researchers are now examining crater floors in the Moon¡¯s southern hemisphere to look for similar trends there.