Water on the Moon Isn’t Just Hiding in the Shadows
By: James Maynard
Tags: Technology, Future, Space, Science, NASA

Water on the Moon has been seen before in the shadows of craters. Now, water has been detected on the sunlit face of the Moon as well.

This illustration highlights the Moon’s Clavius Crater with an illustration depicting water trapped in the lunar soil there, along with an image of NASA’s Stratospheric Observatory for Infrared Astronomy (SOFIA) that found sunlit lunar water. Image credit: NASA

Water is essential to the exploration of the Solar System, and this presents one of the greatest challenges to the colonization of space. The discovery of water ice hidden in the dark recesses of deep craters opens new resources for astronauts as they reach out beyond the Earth. However, accessing that water, deep in treacherous craters, would be challenging.

Water was just found in Clavius Crater, one of the largest craters in the Moon’s southern hemisphere, which is visible from Earth. This suggests water deposits may be found throughout the lunar surface.

Researchers previously saw evidence of water on the sunlit surface of the Moon, but evidence was uncertain. Hydroxyl, a fragment of molecules consisting of one atom each of hydrogen and oxygen, could have created the signal seen by researchers.

Rising Above the Din

SOFIA lifting off on a mission to explore the Cosmos. Image credit: Screenshot from NASA video.

The Stratospheric Observatory for Infrared Astronomy (SOFIA) is a modified Boeing 747SP aircraft, allowing researchers a chance to lift an infrared telescope above most of the interfering water-filled atmosphere of Earth.

Using the Faint Object infraRed CAmera for the SOFIA Telescope (FORCAST) aboard SOFIA, researchers examined the Moon in infrared light, centered at a wavelength of 6.1 microns, confirming the presence of water. This wavelength is seen from molecules of water, but not from hydroxyl, allowing researchers to confirm they were looking at full water molecules.

“We observed a region at high southern latitudes near Clavius crater and a low-latitude portion of Mare Serenitatis… Data from SOFIA reveal a strong 6 [micron] emission band at Clavius crater and the surrounding terrain,” researchers wrote in Nature Astronomy.

The SOFIA discovery explained in one minute. Video credit: NASA/Ames Research Center

The atmosphere of Earth is also fairly quiet at this wavelength, aiding observations with SOFIA.

“Prior to the SOFIA observations, we knew there was some kind of hydration. But we didn’t know how much, if any, was actually water molecules — like we drink every day — or something more like drain cleaner,” said Casey Honniball, from the University of Hawaii at Mānoa in Honolulu.

Water You Doing There?

A look at water on the Moon, SOFIA, and the future of space exploration. Video credit: The Cosmic Companion

How the water got on the Moon remains a mystery. One possibility is it arrived via micrometerorites, depositing water on the Moon. Or, it might form as hydrogen arriving on the solar wind reacts with oxygen in the surface of the Moon forming hydroxyl molecules, which are transformed into water through the impact of micrometeorites.

The water may be now caught up in glass beads, or could be hidden between grains of soil in the form of ice.

All in all, the lunar surface appears to hold, roughly, 12 ounces of water in each cubic meter of lunar surface.

NASA is currently planning to send the first woman and the next man to the Moon in 2024. As human exploration of the Solar System expands, it will be vital to provide colonists with water.

Additional studies will be conducted of the Moon using SOFIA and other instruments, searching for answers to how this water forms, moves, and stays stable in the harsh, sunlit conditions on the lunar surface.