According to the BBC, “Moon's Water Is Useful Resource, Says Nasa”:
Scientists studied the full results of an experiment that smashed a rocket and a probe into a lunar crater last year.
The impacts kicked up large amounts of rock and dust, revealing a suite of fascinating chemical compounds and far more water than anyone had imagined.
A Nasa-led team tells Science magazine that about 155kg of water vapour and water-ice were blown out of the crater.
The researchers’ analysis suggests the lunar regolith, or soil, at the impact site contains 5.6% by weight of water-ice.
“That's a significant amount of water,” said Anthony Colaprete, from the US space agency's Ames research centre.
“And it's in the form of water-ice grains. That's good news because water-ice is very much a friendly resource to work with. You don't have to warm it very much; you just have to bring it up to room temperature to pull it out of the dirt real easy.”
In an article entitled “Lunar ‘Permafrost’: Evidence for Widespread Water Ice on the Moon,” Science Daily writes:
Diviner, an infrared spectrometer aboard NASA's Lunar Reconnaissance Orbiter (LRO), has made the first infrared measurements of temperatures in the permanently shadowed craters at the moon's poles.
. . . . .
UCLA professor of planetary science David Paige, Diviner's principal investigator and lead author of one of the Science papers, used temperature measurements of the lunar south pole obtained by Diviner to model the stability of water ice both at and near the surface. The stability of water ice is an indication that is has existed in a particular location over an extended period of time.
“The temperatures inside these permanently shadowed craters are even colder than we had expected,” Paige said. “Our model results indicate that in these extreme cold conditions, surface deposits of water ice would almost certainly be stable; but perhaps more significantly, these areas are surrounded by much larger permafrost regions where ice could be stable just beneath the surface.”
This lunar ‘permafrost’ is analogous to the high-latitude terrain found on the Earth and on Mars, where subfreezing temperatures persist below the surface throughout the year, Paige said.
The Science article “How Wet the Moon? Just Damp Enough to Be Interesting” (October 22, 2010) has this summary:
The moon's recently discovered hydrosphere is nothing like Earth's watery regime. None of the moon's water is ever liquid. Water in its reservoirs can be imperceptibly sparse, flows into its reservoirs may proceed a few molecules at a time, and none may ever leave. And . . . many enigmas remain.
The full Science article goes on to explain that evidence from India’s Chandrayaan-1 orbiter suggests that some craters near the lunar north pole may have “massive, nearly pure ice just beneath the crater floors. ‘How that would come about I haven't a clue,’ says Spudis, who is principal investigator of the Chandrayaan-1 radar.”
Here are links to NASA’s news about its LRO (Lunar Reconnaissance Orbiter) and LCROSS (Lunar CRater Observation and Sensing Satellite) missions, and here is the home page of the Chandrayaan-1 mission.
Should works about ice on the moon be classed in the interdisciplinary number for the moon—523.3 Moon? Interdisciplinary works about the moon that include something about ice may of course be classed in 523.3 Moon. Works that focus on ice, however, do not belong in 523.3. At 523 Specific celestial bodies and phenomena is the class-elsewhere note: “Class phenomena of celestial bodies directly comparable to terrestrial phenomena with the terrestrial phenomena in 550, e.g., volcanic activity on Mars 551.21099923.” Since class-elsewhere notes have hierarchical force, that note applies to the moon. At 550 Earth sciences is the class-here note: “Class here geophysics; phenomena of celestial bodies directly comparable to terrestrial phenomena, e.g., volcanic activity on Mars 551.21099923.” Class-here notes also have hierarchical force. Further explanation is given in the Manual note 523 vs. 559.9 Earth sciences in extraterrestrial worlds.
What subdivisions of 550 Earth sciences should be used for works about the moon’s ice? At 551.46 Hydrosphere and submarine geology Oceanography is the class-elsewhere note: “Class ice in 551.31.” Also at 553.7 Water is the class-elsewhere note: “Class interdisciplinary works on ice in 551.31.” Should interdisciplinary works about the moon’s ice be classed in 551.31 Geologic work of ice Glaciology? Probably for now, though given today’s limited knowledge about ice on the moon, we would not attempt to predict what number might prove best in the long run. Here are the notes at 551.31:
Class here interdisciplinary works on ice
For ice in water and other forms of ice, see 551.34
For geologic work of frost, see 551.38
Since ice is in the class-here note, further addition is possible; thus ice on the moon would be classed in 551.3109991 Ice on the moon (built with 551.31 plus T1—09 Geographic treatment plus T2—991 Earth's moon).
Depending on treatment, some works about ice on the moon might fit best in 551.38409991 Permafrost on the moon (built with 551.384 Permafrost plus T1—09 plus T2—991).
If the ice in fact turns out to be a valuable resource, works on the economic geology of the moon’s ice might be classed in a subdivision of 553 Economic geology, specifically 553.7 Water, which has the including note “Including ice.” Because ice is mentioned in the including note at 553.7, the topic is in standing room and no further addition is possible.