The “Lunar Volatiles” International Team was proposed to ISSI to address to the recent findings and current development of a new field of lunar science, concerning the origin, transport and accumulation of volatiles at lunar poles. The first suggestion of water ice in polar craters was due to observations of the bistatic radar on board Clementine, the first mission of the new period of lunar exploration began in the 90’s and continuing now. However, this result was not supported by subsequent high-resolution Earth-based radar measurements. Evidence for the presence of water ice in polar regolith was provided by the Lunar Prospector Neutron Spectrometer (LPNS), in the form of extended suppression of neutron emissions around both lunar poles. The first direct detection of polar enhancement of H2O and/or OH in the regolith was performed by means of the M3 hyper-spectral IR mapping spectrometer onboard the ISRO Chandrayaan-1 mission; however such IR data characterize only the uppermost few micrometers of the surface.

The latest proof for the presence of localized areas with a relatively high content of water and other volatiles at the lunar poles has been recently provided by the remote sensing measurements of NASA’s LRO and LCROSS missions: the orbital neutron spectrometer telescope LEND identified the polar crater Cabeus, as the most promising LCROSS impact site with an anomalously high content of hydrogen, and instruments onboard LRO and LCROSS measured direct signatures of water, H2 and another volatiles in the plume material ejected by the LCROSS artificial impact event. The average quantity of water in the regolith of Cabeus was estimated to be about 0.5 – 4.0 % by weight, substantially higher than previously measured amounts of < 0.1 % in regolith at moderate latitudes. These discoveries highlight the exploration of a New Moon at the poles, which is very much different from the Moon studied by Apollo and Lunas.

Main Goals of the Team work:

• GOAL I is to understand the origin of Neutron Suppression Regions (NSRs) at lunar poles with local enhancement of hydrogen in the shallow subsurface, and their relationship to coincident PSRs and daily illuminated regions.
• GOAL II is to consider the physics of newly discovered NSRs, as local lunar environments with concentration of hydrogen-bearing volatiles, and to study the mechanisms of their production, migration and accumulation.
• GOAL III is to perform comparable studies of volatiles on Moon, Mercury, Phobos and comets to understand the origin and evolution of volatiles on the airless celestial bodies in the inner solar system.