Moon had a thicker atmosphere about 3-4 billion years ago, suggests NASA study

Earth's moon had a thicker atmosphere about 3 to 4 billion years ago, which lasted for nearly 70 million years, according to a joint study carried out by scientists from the Lunar and Planetary Institute (LPI) in Houston and NASA’s Marshall Space Flight Center in Alabama.

Moon’s current atmosphere is extremely thin

The atmosphere of today’s Moon is so thin that it is technically called an “exosphere” rather than an “atmosphere.” This exosphere consists of some uncommon gases, including potassium and sodium, which are not found in Earth’s atmosphere.

The number of gas molecules found in the Moon’s exosphere is extremely small compared to those found in Earth’s atmosphere. Moreover, the density of the atmosphere at the lunar surface is comparable to the density of the outermost boundaries of the Earth's atmosphere.

The new study by NASA and LPI, however, suggests that the ancient atmosphere on the Moon was created by giant clouds of gases spewed by Volcanic Eruptions. There were two key sites on the Moon where gases were produced in large amounts—the Serenitatis basin and the Imbrium basin. During the Apollo missions of the 1970s, NASA astronauts collected some rock samples from these two basins, and these samples were then brought to Earth.

Experimental studies of these samples revealed that these rocks contained components of gases including carbon monoxide, sulfur, water, and other volatile species (substances spewed during ancient volcanic eruptions).

Volcanic eruptions created temporary atmosphere on ancient Moon

LPI’s David A. Kring and NASA’s Debra H. Needham carried out a new study on these rock samples to calculate the amounts of gases released from the lava during ancient volcanic eruptions.

The findings revealed that the gases released during eruptions were enough to create a temporary atmosphere on the Moon. With the increase in eruptions, the thickness of the atmosphere also increased, which attained its peak level about 3.5 billion years ago. However, this temporary atmosphere lasted only for about 70 million years and eventually evaporated into space.

According to LPI scientists, these results could have larger implications for future lunar missions as the volatiles substances from the Moon's ancient atmosphere could be trapped as icy deposits in areas near Moon's poles and might provide a source of fuel and air for astronauts going to the Moon.

The detailed findings of the study were published in the journal "Earth and Planetary Science Letters."