Water on the moon?

May 30, 2016, Harvard University
Water on the moon?
This illustration shows a promising new technique for locating water on the Moon. Galactic cosmic rays (GCR) that penetrate the lunar surface, when encountering a layer with material containing hydrogen atoms (like water), trigger the ejection of protons (red spheres) that can be detected by the appropriate instrumentation in an orbiting satellite. Credit: Schwadron et al. 2016

Prior to the Apollo missions to the moon, scientists speculated that volatiles - including water - may have accumulated in permanently shaded regions at the poles. Then the Apollo era brought the return of lunar samples, enabling real measurements: They found none of the water-bearing minerals common on Earth. Over the past ten years, however, several developments have reinvigorated the discussion. In particular, new analyses of volcanic glasses in the sample returns have inferred the presence of water in the moon's interior. Meanwhile, several new lunar missions have been launched. The ones using neutron spectroscopy to search for water have come up with mixed conclusions, but those using infrared spectroscopy seemed to reach unambiguous identification of water on the lunar surface, although in disagreement with the neutron experiments.

CfA astronomers Anthony Case and Justin Kasper were members of a team of astronomers who propose a new method to detect hydrated material on the moon - like water - by measuring the strength of protons coming from the lunar surface with the CRaTer instrument (Cosmic Ray Telescope for the Effects of Radiation) on the Lunar Reconnaissance Orbiter, a NASA robotic orbiter launched in 2009. Cosmic rays from the galaxy, when striking the lunar surface, will knock protons out of material on the surface which can be detected by the CRaTER instrument. The team completed a set of laboratory tests using high energy particle accelerators to simulate the effects of on materials containing hydrogen, and found that the presence of hydrogen - in water for example – actually suppresses the overall proton emission. The implication is that if water is present near the poles of the moon, a scan across the should show a clear reduction in numbers of protons as it crosses the poles.

Actually, the CRaTER scans found an increase in the proton emission at the poles. The scientists soon realized that there were some effects, originally thought to be negligible, that were responsible. Protons and neutrons, released from material below the surface down to about ten centimeters, will collide with other atoms and produce the emission of secondary particles. The enhancement of these secondary is indeed consistent with the presence of hydrogen. But it turns out that there are other possible solutions as well, and the team is continuing to investigate them. Meanwhile their current paper shows that the technique of using CRaTER measurements to search for water is at least in principle possible, and when the remaining issues are resolved, the techniques could be used in other missions to probe other solar system bodies.

Explore further: Digging deep in search of water on the moon

More information: N.A. Schwadron et al. Signatures of volatiles in the lunar proton albedo, Icarus (2016). DOI: 10.1016/j.icarus.2015.12.003

Related Stories

Digging deep in search of water on the moon

May 19, 2014

One of the main aims of the Apollo missions of the 1960s was to determine whether the moon had any water on it. If man were to build a colony on the moon, having water present would make living there easier.

Characterizing the Moon's radiation environment

April 9, 2013

The radiation environment near the Moon could be damaging to humans and electronics on future missions. To characterize this potentially hazardous environment, the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) ...

Metamorphosis of moon's water ice explained

June 19, 2013

Using data gathered by NASA's Lunar Reconnaissance Orbiter (LRO) mission, scientists believe they have solved a mystery from one of the solar system's coldest regions—a permanently shadowed crater on the moon. They have ...

Recommended for you

Magnetized inflow accreting to center of Milky Way galaxy

August 17, 2018

Are magnetic fields an important guiding force for gas accreting to a supermassive black hole (SMBH) like the one that our Milky Way galaxy hosts? The role of magnetic fields in gas accretion is little understood, and trying ...

First science with ALMA's highest-frequency capabilities

August 17, 2018

The ALMA telescope in Chile has transformed how we see the universe, showing us otherwise invisible parts of the cosmos. This array of incredibly precise antennas studies a comparatively high-frequency sliver of radio light: ...

Another way for stellar-mass black holes to grow larger

August 17, 2018

A trio of researchers with The University of Hong Kong, Academia Sinica Institute of Astronomy and Astrophysics in Taiwan and Northwestern University in the U.S., has come up with an alternative theory to explain how some ...

Six things about Opportunity's recovery efforts

August 17, 2018

NASA's Opportunity rover has been silent since June 10, when a planet-encircling dust storm cut off solar power for the nearly-15-year-old rover. Now that scientists think the global dust storm is "decaying"—meaning more ...

Sprawling galaxy cluster found hiding in plain sight

August 16, 2018

MIT scientists have uncovered a sprawling new galaxy cluster hiding in plain sight. The cluster, which sits a mere 2.4 billion light years from Earth, is made up of hundreds of individual galaxies and surrounds an extremely ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.