Scientists last year observed evidence of water ice on the Moon’s surface.
Located in the darkest and coldest parts of its polar regions, these patchy deposits are likely billions of years old. But some, according to new research, may be much more recent.
“The ages of these deposits can potentially tell us something about the origin of the ice, which helps us understand the sources and distribution of water in the inner Solar System,” lead study author Ariel Deutsch, a graduate student at Brown University, said in a statement.
Working with Brown professor Jim Head and Gregory Neumann of the Goddard Space Flight Center, Deutsch studied data from NASA’s Lunar Reconnaissance Orbiter, which has been circling the Moon since 2009.
A majority of the reported ice deposits were found within large craters formed some 3.1 billion years (or longer) ago; patchy distribution suggests the ice has been battered by debris over a long period.
Analysts, however, also found evidence of ice in smaller craters, which appear to be “quite fresh,” Brown boasted, suggesting some deposits on the south pole emerged relatively recently.
“That was a surprise,” Deutsch said. “There hadn’t really been any observations of ice in younger cold traps before.”
Differently aged deposits also indicates different sources: Older ice could have come from water-bearing comets and asteroids or volcanic activity—neither of which are a problem today.
So more recent ice must have developed from something else—perhaps bombardment of pea-sized micrometeorites or implantation by solar wind.
The best way to find out, the researchers said, is to send a spacecraft to collect samples.
That’s what NASA did with its Moon Mineralogy Mapper (M3), which helped researchers identify three specific signatures that “definitely prove” there is water ice on Earth’s satellite.
The machine not only picked up reflective properties expected of ice, but also measured the distinctive way its molecules absorb infrared light, allowing researchers to differentiate between liquid water or vapor and solid ice.
Most of the newfound water ice is situated in the shadows of craters near the orb’s poles, where the temperature never reaches above a balmy -250 ℉. The tiny tilt of the Moon’s rotation axis, NASA explained, restricts sunlight from reaching these regions.
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