Shattering a long-held belief that Earth’s moon is a dead and dry world, a trio of spacecraft uncovered clear evidence of water and hydrogen-oxygen molecules throughout the lunar surface.Aside from scientific interest, finding water on the moon could impact plans for eventual human settlements beyond Earth, said geologist Paul Spudis, with the Houston-based Lunar and Planetary Institute.
An instrument on board the ill-fated Chandrayaan-1 spacecraft, the Moon Mineralogy Mapper (M cubed) found that infrared light was being absorbed near the lunar poles at wavelengths consistent with hydroxyl- and water-bearing materials.
M3 analyzes the way that light from the sun reflects off the lunar surface to understand what materials comprise the lunar soil. Light is reflected in different wavelengths off of different minerals, and specifically, the instrument detected wavelengths of reflected light that would indicate a chemical bond between hydrogen and oxygen. Given water’s well-known chemical symbol, H2O, which represents two hydrogen atoms bonded to one oxygen atom, this discovery was a source of great interest to the researchers.
The instrument can only see the very uppermost layers of the lunar soil – perhaps to a few centimeters below the surface. The scientists were looking for a signature of water in the craters near the poles, but found evidence for water instead on the sunlit portions of the moon. This was certainly unexpected and the science team from M3 looked and re-looked at their data for several months.
Scientists have suspected water could exist inside deep craters at the moon’s poles that are never exposed to sunlight. The new research is surprising because it found chemical bonds between hydrogen and oxygen throughout the lunar surface. The concentrations appear denser near the polar regions.
How much water and hydroxyl is on the moon and where it came from remains a mystery.
Data indicate that water exists diffusely across the moon as hydroxyl or water molecules — or both — adhering to the surface in low concentrations.
The message the scientists wanted everyone to take away is that a combination of water (H2O) and hydroxyl (OH) that resides in upper millimeter of the lunar surface doesn’t actually amount to much. The average amount of water, if extracted, is about a quart (1 liter) of water per ton of surface soil, or about 16 ounces (.5 liters) of water might be present for every 1,000 pounds (450 kg) of surface soil near the moon’s poles. For soil near the equator, only about two tablespoons of water is believed to be present in every 1,000 pounds (450 kg).
“That is truly astounding, and generating much excitement,” said Jim Green, director of the Planetary Science Division at NASA. “But please keep in mind that even the driest deserts on the Earth have more water than are at the poles and the surfaces of the moon.”
So maybe this water on the Moon is not such a big deal.
But there’s still the very real possibility that there could be water ice underneath the regolith on the Moon or buried deep within craters at the poles. Fairly recent (within the past million years) impact craters on the moon were found to have ejecta “rich” with water and hydroxyl, according to M cubed data, which implies recently those molecules are buried under the surface.
Watch Out for Future Missions.