Washington: New maps produced by the Lyman Alpha Mapping Project (LAMP) aboard NASA’s Lunar Reconnaissance Orbiter have revealed features of the Moon’s northern and southern poles in regions that lie in perpetual darkness.
LAMP, developed by the Southwest Research Institute (SwRI), uses a novel method to peer into these so-called permanently shadowed regions (PSRs), making visible the invisible.
The LAMP maps show that many PSRs are darker at far-ultraviolet wavelengths and redder than nearby surface areas that receive sunlight.
They show many permanently shadowed regions (PSRs), are darker at far-ultraviolet wavelengths (top) and redder than nearby surface areas that receive sunlight (bottom).
The darker PSR regions are consistent with having large surface porosities, indicating “fluffy” soils, while the reddening is consistent with the presence of water frost on the surface.
“Our results suggest there could be as much as 1 to 2 percent water frost in some permanently shadowed soils,” Randy Gladstone, the study author, said.
“This is unexpected because naturally occurring interplanetary Lyman-alpha was thought to destroy any water frost before it could accumulate,” Gladstone said.
The LAMP team estimates that the loss of water frost is about 16 times slower than previously believed. In addition, the accumulation of water frost is also likely to be highly dependent on local conditions, such as temperature, thermal cycling and even geologically recent “impact gardening” in which micrometeoroid impacts redistribute the location and depth of volatile compounds.
Finding water frost at these new locations adds to a rapidly improving understanding of the Moon’s water and related species, as discovered by three other space missions through near-infrared emissions observations and found buried within the Cabeus crater by the LCROSS impactor roughly two years ago.
“An even more unexpected finding is that LAMP’s technique for measuring the lunar Lyman-alpha albedo indicates higher surface porosities within PSRs, and supports the long-postulated presence of tenuous ‘fairy-castle’ like arrangements of surface grains in the PSR soils,” Kurt Retherford, the study co-author, said.
The study has been published in the Journal of Geophysical Research.