Artemis I Mission Reveals Radiation Levels Near Moon Higher Than Earth Orbit

NASA’s Artemis I mission has provided new insights into cosmic radiation levels near the Moon. Using experimental detectors aboard the Orion spacecraft, researchers found that radiation exposure in the lunar environment is higher than in low Earth orbit, though the difference is not as large as some had intuitively expected, according to researchers from the Henryk Niewodniczanski Institute of Nuclear Physics Polish Academy of Sciences (IFJ PAN).

Radiation Detection Methods

During the uncrewed Artemis I mission in late November and early December 2022, the Orion spacecraft carried more than 10,000 tiny crystals embedded inside two human-shaped mannequins. These devices were part of the Matroshka AstroRad Radiation Experiment (MARE) study.

Among the detectors were several dozen experimental fluorescent lithium fluoride detectors created by scientists at IFJ PAN. These detectors work by capturing microscopic changes caused by radiation. When electrically charged particles pass through a crystal, they create defects known as "color centers." When illuminated with blue light, these regions glow red, allowing researchers to identify particle paths under a microscope.

Prof. Pawel Bilski of IFJ PAN, a co-author of the study published in the journal Radiation Measurements, explained, "The fluorescent radiation dose detectors based on lithium fluoride, developed at our institute, are passive in nature. In other words, they work like photographic film: once the crystals have been exposed to radiation, the tracks left by individual particles must be analyzed optically under a microscope."

Comparison of Radiation Environments

Researchers compared the Artemis I data to the MATROSHKA experiment conducted over a decade ago aboard the International Space Station. The findings revealed distinct differences in how radiation is distributed:

• Low Earth Orbit: Radiation is largely composed of low-energy protons trapped within Earth's Van Allen radiation belts. These particles deposit energy at different depths, creating an uneven distribution of radiation doses within the mannequins.
• Lunar Orbit: The Van Allen belts do not extend to the Moon. Consequently, radiation near the Moon is dominated by high-energy galactic cosmic rays that can pass through the entire human body, resulting in radiation doses that are distributed almost uniformly throughout the mannequins.

"Low-energy protons, trapped by our planet's magnetic field within the Van Allen belts, can account for the majority of the radiation dose received by astronauts in low Earth orbit. In the vicinity of the Moon, this substantial contribution disappears," Prof. Bilski noted. "Our measurements from the MARE experiment indicate that, although total radiation doses near the Moon are higher than those in Earth orbit due to the considerable levels of galactic radiation, the difference is not as large as one might intuitively expect."

Implications for Future Missions

The lithium fluoride detectors used in the mission were grown using the Czochralski method and are small enough to be worn by people. Because they do not require the chemical etching needed for traditional plastic detectors, they allow for more straightforward observation of particle tracks.

These findings are considered significant for planning future crewed lunar missions, as understanding these radiation levels will assist in the development of shielding technologies to protect astronauts in deep space.

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Sources

• sciencedaily.com: NASA’s Artemis I mission reveals surprising radiation levels near the Moon | ScienceDaily
• ua.news: NASA has detected dangerously high levels of cosmic radiation near the Moon | UA.NEWS
• scitechdaily.com: NASA’s Artemis I Reveals a Surprising Radiation Mystery Near the Moon
• inkorr.com: Artemis I detects high lunar cosmic radiation levels without critical risk
• news.ssbcrack.com: NASA's Artemis I Mission Reveals New Insights on Cosmic Radiation Near the Moon - SSBCrack News

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