Has ice really been detected on the Moon?

The Clementine 1 mission's radar reflectometer found material in the permanently shaded regions of the lunar south pole which SEEMS to be an ice-type material.

In 2008, NASA's Lunar Reconnaissance Orbiter mapped the south polar region and ejected an Impactor that produced a cloud of lunar dust when it struck the shadowed surface of a crater .The result was the detection of significant amounts of water, suhhesting that the lunar solis in these shadowed polar craters do indeed have sub-surface ice deposits!

Figure: LRO Diviner Lunar Radiometer Experiment surface temperature map of the south polar region of the moon. Data were acquired during September and October 2009, when south polar temperatures were close to their annual maximum values. The map shows the locations of several intensely cold impact craters that are potential cold traps for water ice, as well as a range of other icy compounds commonly observed in comets. The approximate maximum temperatures at which these compounds would be frozen in place for more than a billion years is shown next to the scale on the right.

UCLA Press Release October 21, 2010:

Scientists from NASA's Diviner Lunar Radiometer Experiment team have detected the widespread presence of water ice in large areas of the moon's south pole. Their findings appear Oct. 22 in two papers published in the journal Science. The research was funded by NASA. 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.

In October 2009, Diviner also made the first infrared observations of a controlled impact on the moon, when NASA's Lunar Crater Observation and Sensing Satellite (LCROSS), the companion spacecraft to the LRO, slammed into one of the coldest of these craters in an experiment to confirm the presence or absence of water ice.

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 it 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. "These permafrost regions may receive direct sunlight at certain times of the year, but they maintain annual maximum subsurface temperatures that are sufficiently cold to prevent significant amounts of ice from vaporizing," he said. Given that these permafrost regions are not in permanent shadow, surface lighting and thermal conditions in these locations would be far more hospitable for humans, which makes them of prime interest for future manned missions to the moon, Paige said. Subsurface water ice deposits are also likely to be more stable than surface deposits of water ice because they are protected from bombardment by ultraviolet radiation and energetic cosmic particles. "We conclude that large areas of the lunar south pole are cold enough to trap not only water ice but other volatile compounds (substances with low boiling points) such as sulphur dioxide, carbon dioxide, formaldehyde, ammonia, methanol, mercury and sodium," Paige said.