Indeed, it is the milestone study that has revealed meteorite impacts as the real cause behind the enigmatic tenuous atmosphere of the Moon. Now, one realizes from the careful analyses of lunar samples returned by the Apollo missions that a play exists between the surface and the exosphere of the Moon.
The existence of the moon’s atmosphere was discovered during the NASA lunar expeditions in the 1960s and 70s. The atmosphere hovering over the moon is much tenser than on planet Earth, which was initially cited to be caused by space weathering on the lunar surface. Recent findings state that meteorite impacts are the chief contributors to this very thin veil made up of atmospheric particles.
“Our findings provide a clearer picture of how the moon’s surface and atmosphere interact over long timescales and enhance our understanding of space weathering processes,” said Dr. Nicole Nie, co-author of the study and a planetary scientist at MIT.
The study, found in the journal Science Advances, elucidates that the moon’s atmosphere, technically an exosphere, must be constantly replenished because it is so diaphanous and almost a space. This replenishment is needed since atoms can readily escape into space or else become trapped on the lunar surface since the latter has only a weak gravity. Although ultraviolet photons from the sun can rerelease trapped atoms, the key replenishment mechanisms are vaporization by meteorite impacts and solar wind sputtering, in which charged particles from the sun trigger atoms to get ejected from the lunar surface.
The study, which was based on data collected by the Lunar Atmosphere and Dust Environment Explorer launched by NASA in 2013, looked, through this research, to establish the most viable process through which the lunar atmosphere could be maintained. By testing isotopes of potassium and rubidium present within ten samples of the lunar soil brought back to the Earth by Moonshots, the researchers found that meteorite impact accounted for around 70% of the moon’s atmospheric replenishment, while solar wind sputtering accounts for the remaining 30%.
Dr. Simeon Barber, senior research fellow with the Open University, said these results drive home the importance of understanding lunar dynamics. “Understanding just how this thin atmosphere forms on moons and small planets helps us understand how these bodies have come to be so varied,” he said. He also added possibilities for comparable studies on the Martian moons Phobos and Deimos.
The study, once again, underscored the intrinsic value of samples that have been brought by Apollo missions and which have been capable of providing critical inputs into lunar science. “Using samples brought back from the Apollo missions is both an honor and a unique scientific opportunity,” said Nie. Even today, over 50 years since they were first collected, such samples prove very valuable in scientific research.
“Future especially into the moon’s south polar region likely to continue to sophisticate our understanding of lunar processes,” said Myriam Lemelin, a geologist with the Universite de Sherbrooke. Potential future missions could return new samples for the investigation of isotopic compositions and, more generally, for the measurements of various aspects of the moon’s atmosphere.
In other words, despite the inability of the scattered particles on the moon’s exosphere to support breathing to future lunar explorers, knowledge regarding its origin due to meteorite impacts and solar wind provides a deep insight into the history of evolution of the moon and the general dynamism of celestial bodies. This information will be critical to future lunar missions and also in setting up possible habitats on the moon.