Once again, in the quest for lunar resources, scientists used data from NASA’s Lunar Reconnaissance Orbiter to try and find water ice. They studied shaded areas and concluded that up to 20 percent of the frozen water on the Moon could be in small cold traps scattered over the polar regions. These cold traps are not only shadowed but could be more accessible to lunar rovers. 

PSI senior scientist Norbert Schörghofer explains: Future lunar rovers may have a hard time driving into a large dark crater with extremely low temperatures. Small cold traps are far more accessible. Approximately 10 to 20% of the permanent cold-trap area for water is found to be contained in these micro cold traps. In terms of numbers, most cold traps are smaller than 1 meter.

Co-author and also a senior scientist at PSI Oded Aharonson goes on to say: The smaller deposits should be more accessible for at least two reasons: the distance to the nearest one from a hypothetical landing site might be shorter, and the deposit would not be surrounded by imposing tall crater rims, but rather much gentler slopes.

A lot of the work here is theoretical since even the LRO cannot give us the spatial resolution to see these micro traps. Instead, the team did a statistical analysis using several extrapolation techniques to determine the potential number of micro traps on the lunar surface. 

For example, per the press release: ...the team calculated how the instantaneous shadow in a crater for a given height of the Sun above the horizon is related to the extent of the truly permanent shadow in that crater. They then measured the extent of shadows in thousands of images of the lunar surface for various Sun elevations, and combined the measurements with the geometric factors to estimate the total area in permanent shadow. They also calculated the temperatures of these areas to predict in which one’s ice can accumulate.

And my son thinks geometry is useless.

So while looking for a thimbleful of water in 1000 thimbles full of regolith sounds extremely energy-intensive, driving into a small cold trap with shallow slopes to access a water ice deposit with your lunar rover sounds relatively simple. Both of these studies aid in the quest for lunar resources, and I’m sure there will be more to come as we get closer to the launch of NASA’s Artemis mission.

More Information

PSI press release 

“Micro Cold Traps on the Moon,” P. O. Hayne, O. Aharonson & N. Schörghofer, 2020 Oct. 26, Nature Astronomy (preprint on arxiv.org)