The ancient atmosphere of our Moon

A recent study has revealed that the ancient Moon once had an atmosphere believed to be 3-4 billion years ago. The atmosphere was created due to the intense volcanic eruptions which spewed gases above the surface faster than they could escape to space. The dark surfaces that are seen on the moon are the volcanic basalts that fill the large impact basins. Analysis of the Apollo samples indicated that magmas generated from the eruptions of seas of basalts carried gas components such as carbon monoxide, the ingredients for water, sulfur, and other volatile species.

Dr. Debra H. Needham, Research Scientist of NASA Marshall Space Flight Center, and Dr. David A. Kring, Universities Space Research Association (USRA) Senior Staff Scientist, at the Lunar and Planetary Institute (LPI), who were doing the study, calculated the amounts of gases that came out from erupting lavas as they flowed over the lunar surface for hundreds of kilometres and revealed that those gases got accumulated around the Moon to form a transient atmosphere.

It was also observed that the atmosphere of Moon was thickest during the pick in volcano activity around 3.5 billion years ago and might have persisted for about 70 million years before it got immersed in space. The study revealed that two largest pulses of gas were produced when lave seas filled the Imbrium and Serenitatis basins about 3.5 and 3.8 billion years ago, respectively. The margins of those lava seas were explored by astronauts of the Apollo 15 and 17 missions, who collected samples that not only provided the ages of the eruptions but also contained evidence of the gases produced from the erupting lunar lavas.

David Kring said that this work dramatically changed their view of the Moon from an airless rocky body to one that used to be surrounded by an atmosphere more prevalent than that surrounding Mars today. He also informed that when this type of atmosphere was present in Moon, the Moon was nearly three times closer to Earth and it is today.

This new discovery by Needham and Kring indicated that volatiles must have been trapped inside ice present in cold, permanently shadowed regions near the lunar poles. These volatiles present inside icy deposits could provide air and fuel for astronauts conducting lunar surface operations and, potentially, for missions beyond the Moon. The study was published in Earth and Planetary Science Letters and was supported by NASA’s Solar System Exploration Research Virtual Institute


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