NASA mission aims to study ice and water on the moon’s surface

In the fall of 2023, a U.S. rover will land at the south pole of the moon. Its mission: to explore the water ice that scientists know lurks within the lunar shadows, and which they believe could help sustain humans who may one day explore the moon or use it as a launching pad for more distant space exploration.

NASA recently selected Kevin Lewis, an associate professor in the Krieger School’s Department of Earth and Planetary Sciences who has also worked on missions on Mars, as a co-investigator of the mission. Using part of the rover’s navigational system, he plans to explore the moon’s subsurface geology from his office in Olin Hall.

“I have been on other rover missions, but on Mars, so I’m a little bit new to the moon,” Lewis said. “We’re going to see into shadows that have never seen the sun, let alone been seen by humans. So it could be a very different type of surface than we’ve seen in other photos of the surface of the moon.”

Drier than a desert

Most of the moon is completely without water. That’s because of the way the satellite was formed, in a giant impact between the proto-Earth and a Mars-size object. Temperatures were high enough not only to melt rock, but to vaporize it, causing a cloud of rock vapor to orbit Earth. The vapor eventually coalesced to form the moon.

Those temperatures were also high enough to drive off any water, not even leaving appreciable traces trapped within rocks the way it is on Earth. But over time, meteors and comets containing water ice bombarded the moon, sending ice molecules hopping around the lunar surface.

The sun’s angle at the moon’s poles is steep, creating long shadows. This means that some of the polar craters receive no sunlight at all. When the water molecules happen to hop into one of those unlit areas, whose temperatures are among the coldest in the solar system at just tens of degrees above absolute zero, it drains their thermal energy and they remain stuck to the surface.

“So, over time, you could build up ice deposits in these permanently shadowed regions, which might be basically the only source of water on the entire moon in useful quantities,” Lewis said.


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