Tiny iron nanoparticles unlike any found naturally on Earth are nearly
everywhere on the moon—and scientists are trying to understand why. A new
study led by Northern Arizona University doctoral candidate Christian J. Tai
Udovicic, in collaboration with associate professor Christopher Edwards,
both of NAU's Department of Astronomy and Planetary Science, uncovered
important clues to help understand the surprisingly active lunar surface. In
an article recently published in Geophysical Research Letters, the
scientists found that solar radiation could be a more important source of
lunar iron nanoparticles than previously thought.
Asteroid impacts and solar radiation affect the moon in unique ways because
it lacks the protective magnetic field and atmosphere that protect us here
on Earth. Both asteroids and solar radiation break down lunar rocks and
soil, forming iron nanoparticles (some smaller, some larger) that are
detectable from instruments on satellites orbiting the moon. The study used
data from National Aeronautics and Space Administration (NASA) and Japan
Aerospace Exploration Agency (JAXA) spacecraft to understand how quickly
iron nanoparticles form on the moon over time.
"We have thought for a long time that the solar wind has a small effect on
lunar surface evolution, when in fact it may be the most important process
producing iron nanoparticles," Tai Udovicic said. "Since iron absorbs a lot
of light, very small amounts of these particles can be detected from very
far away—making them a great indicator of change on the moon".
Surprisingly, the smaller iron nanoparticles seemed to form at a similar
rate as radiation damage in samples returned from the Apollo missions to the
moon, a hint that the sun has a strong influence in 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
the solar radiation could have a much larger influence in active change on
the moon than previously thought, not only darkening its surface, but it
might also create small quantities of water usable 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, understanding the solar
radiation environment and possible resources on the moon are critical. In
future work recently awarded a NASA Future Investigators in Space Science
and Technology (FINESST) grant, Tai Udovicic plans to broaden his targeted
study to the entire moon, but is also eager to take a closer look at
mysterious lunar swirls, one of which was recently selected as a landing
site for the upcoming Lunar Vertex rover. He also studies lunar temperatures
and water ice stability to inform future missions.
"This work helps us understand, from a bird's eye view, how the lunar
surface changes over time," said Tai Udovicic. "While there is still a lot
to learn, we want to make sure that when we have boots back on the moon,
that those missions are backed by the best science available. It's the most
exciting time to be a lunar scientist since the tail end of the Apollo era
in the 70s."
Reference:
C. J. Tai Udovicic et al, New Constraints on the Lunar Optical Space
Weathering Rate, Geophysical Research Letters (2021).
DOI: 10.1029/2020GL092198
Tags:
Space & Astrophysics