Planetary scientists find evidence of solar-induced changes on the Moon

PhD student discovers solar radiation could be a bigger source of lunar iron nanoparticles than previously thought.

Tiny iron nanoparticles, different from those found naturally on Earth, are found almost everywhere on the Moon, and scientists are trying to figure out why. A new study led by Northern Arizona University doctoral candidate Christian J. Tai Udovicic in collaboration with Associate Professor Christopher Edwards, both of the NAU Department of Astronomy and Planetary Sciences, has uncovered important clues to help understand the surprisingly active lunar surface. In an article recently published in Geophysical research letters, scientists have discovered that solar radiation may be a larger source of lunar iron nanoparticles than previously thought.

Asteroid impacts and solar radiation affect the Moon in a unique way because it lacks the protective magnetic field and atmosphere that protects us here on Earth. Asteroids and solar radiation break down lunar rocks and the ground, forming iron nanoparticles (some smaller, others larger) that can be detected by instruments on satellites orbiting the moon. The study used data from the National Aeronautics and Space Administration (Nasa) and the Japan Aerospace Exploration Agency (JAXA) to understand how quickly iron nanoparticles form on the Moon over time.

“We have long believed that the solar wind has a small effect on the evolution of the lunar surface, when in fact it could be the most important process producing iron nanoparticles,” said Tai Udovicic. “Since iron absorbs a lot of light, very small amounts of these particles can be detected from a great distance, making it a great indicator of change on the Moon.”

Surprisingly, the smaller iron nanoparticles appeared to form at a rate similar to the radiation damage in samples returned from the Apollo missions to the moon, a hint that the Sun has a strong influence on their formation.

“When I saw the Apollo sample data and our satellite data side by side for the first time, I was shocked,” Tai Udovicic said. “This study shows that solar radiation could have a much greater influence on active change on the Moon than previously thought, not only by darkening its surface, but it could also create small amounts of usable water in future missions. “

As NASA prepares to land the first woman and the next man on the surface of the moon by 2024 as part of the Artemis mission, it is essential to understand the solar radiation environment and possible resources on the moon. the moon. In future work recently awarded a grant from NASA Future Investigators in Space Science and Technology (FINESST), Tai Udovicic plans to expand his focused study to the entire Moon, but also wants to take a closer look at the mysterious vortices. lunars, one of which was recently selected as the landing site for the upcoming Lunar Vertex rover. He is also studying lunar temperatures and the stability of water ice to inform future missions.

“This work helps us understand, as the crow flies, how the lunar surface changes over time,” Tai Udovicic said. “While there is still a lot to learn, we want to make sure that when we get our boots on the Moon again, these missions will be supported by the best science available. This is the most exciting time to be a lunar scientist since the end of the Apollo era in the 1970s. ”

Reference: “New Constraints on the Lunar Optical Space Weathering Rate” by CJ Tai Udovicic, ES Costello, RR Ghent and CS Edwards, June 19, 2021, Geophysical research letters.
DOI: 10.1029 / 2020GL092198