Terrestrial Particles Travel to the Moon by Hitchhiking Along Earth’s Magnetic Field Lines

One of the key challenges in building and sustaining a permanent settlement on the moon, as in 2001: A Space Odyssey, is finding a reliable and economical means of transporting essential resources, such as water and energy.

The good news is that while the moon may look like a barren wasteland — and, according to NASA, be a hundred times drier than the Sahara — it is not quite as desolate as it first appears. This is because for billions of years, particles have travelled from our atmosphere to its surface via the Earth’s geomagnetic field, scientists at the University of Rochester reported in the journal Communications Earth & Environment.

"By combining data from particles preserved in lunar soil with computational modeling of how solar wind interacts with Earth's atmosphere, we can trace the history of Earth's atmosphere and its magnetic field," Eric Blackman, a professor in the Department of Physics and Astronomy and a distinguished scientist at URochester's Laboratory for Laser Energetics (LLE), said in a statement.

Read More: Earth and the Mysterious Planet Theia Were Likely Close Neighbors Before the Moon Formed

Analyzing The Composition Of Lunar Soil

It has been more than 50 years since humans last set foot on the moon, but samples from earlier missions led to the findings.

A previous analysis of these soil samples found light volatile elements, such as hydrogen, helium, neon, argon, and nitrogen. Crucially, these substances have been found in lunar soil but not in lunar rock, meaning they must have come from elsewhere. While their presence can, in part, be attributed to the steady stream of particles that emanates from the sun (solar wind), the volume of nitrogen in the soil suggests there is at least one additional source.

A few theories have been put forward, including those that suggest the light volatile elements arrived on interplanetary dust, through asteroid collisions, or from the gas of lunar volcanoes. However, one leading theory is that the particles have a terrestrial origin.

If this is indeed the case, the question is: when and how did they travel from Earth to the moon? In 2005, a separate team of researchers made the case that the particles made the journey before the formation of Earth’s magnetic field. Twenty years later, Blackman and co put that theory to the test.

Hitchhiking On Earth's Magnetic Field Lines

To do so, the team used complex computer simulations to model two different scenarios: one involving a primitive Earth with no magnetic field and stronger solar wind, and one involving a modern Earth with a strong magnetic field and weaker solar wind. Of the two, the latter was the best-fit scenario.

According to the results, ions in Earth’s atmosphere are displaced by solar wind and shepherded along Earth’s magnetic field lines. This happens most efficiently when the moon falls within the Earth’s magnetotail — i.e., the elongated section of Earth’s magnetic field, which falls on the side furthest from the sun.

The only element that could not be accounted for in either model is hydrogen. This, the researchers explain, suggests it has a solar or extrasolar origin and not a terrestrial origin.

Resourcing Lunar Bases

The findings could have important implications when it comes to resourcing future expeditions to the moon, with the particles offering a nearby source of essential substances like water and nitrogen.

“By examining planetary evolution alongside atmospheric escape across different epochs, we can gain insight into how these processes shape planetary habitability,” Shubhonkar Paramanick, a graduate student in the Department of Physics and Astronomy and a Horton Fellow at the LLE, said in a statement.

Read More: The Moon Is Moving Farther From Earth Each Year, and Tides Are the Reason

Article Sources

Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:

• This article references information from the recent study published in Communications Earth & Environment, Terrestrial atmospheric ion implantation occurred in the nearside lunar regolith during the history of Earth’s dynamo
• This article references information from NASA: Water & Ices on the Moon