Leonard David's INSIDE OUTER SPACE

Map of the distribution of subsurface water ice in Cabeo Crater. Image credit: Department of Nuclear Planetology of the Space Research Institute of the Russian Academy of Sciences.

New views of water ice resident in polar craters of the Moon have been issued by the Space Research Institute of the Russian Academy of Sciences.

The data has been collected by the Russian Lunar Exploration Neutron Detector (LEND), an experiment on board NASA’s Lunar Reconnaissance Orbiter (LRO) that was launched back in June 2009.

Based on measurements taken by the Russian neutron telescope onboard LRO, the features of water ice occurrence in the lunar polar craters Cabeo and Galimov were studied.

Large volume of data

According to a December 24 posting on the Press Service Bulletin of the Space Research Institute of the Russian Academy of Sciences (IKI RAS), LEND has accumulated a large volume of neutron mapping data over 15 years of work.

In the soil of the polar crater Cabeo, the mass fraction of water ice is on average about 0.5%, and in some areas even 0.7%. Polar crater Cabeo coordinates are 35.5 W, 84.9 S. 

“Such an area ‘enriched’ with water ice is located at the deepest point of the permanently shadowed section of the crater Cabeo,” the website explains. “The mass fraction of ice in the soil of this crater increases with depth, and ice is present in both sunlit and permanently shadowed areas of the surface.”

Galimov Crater. Image credit: Department of Nuclear Planetology of the Space Research Institute of the Russian Academy of Sciences.

Crater ages

Russia’s LEND also observed the polar crater Galimov located closer to the equator at coordinates 126.59° W, 64.32° S. This feature is comparable to the Cabeo crater in age – 3.85 billion years. However, Galimov is nearly three times smaller in diameter than crater Cabeo, roughly 21 miles (34 kilometers) across.

“It turned out that there are no signs of water ice in the soil at its bottom. At the same time, the soil in the immediate vicinity of the crater contains water ice,” the posting adds.

The research work was carried out by a team of the Department of Nuclear Planetology of the Space Research Institute of the Russian Academy of Sciences under the supervision of Igor Mitrofanov. Also cited in the research, Maxim Litvak, Anton Sanin, and Maya Dyachkova.

Installing Russia’s LEND device on the Lunar Reconnaissance Orbiter (LRO) by NASA Goddard Space Flight Center specialists.
Image credit by IKI RAS

History of lunar permafrost

The scientists explain that the absence of ice in the Galimov crater basin is due to the eruption of hot magma, which took place between 0.2 and 1.0 billion years ago, as evidenced by cracks on the bottom of the crater.

“Thus, a comparison of these two craters showed that the polar glaciers on the Moon formed between 3.85 billion and 1.0 billion years ago,” the IKI RAS specialists point out.

The researchers add that additional study of the lunar soil using neutron orbital mapping data “will help to reconstruct in even greater detail the history of the appearance of permafrost on the Moon and also solve the practical problem of choosing the optimal location for a future lunar base.”

NASA’s Lunar Reconnaissance Orbiter (LRO).
Credit: NASA/GSFC

Fairly “wet” place

According to an overview of the work of LEND, maps of the prevalence of water in the lunar regolith at the north and south poles of the Moon have been developed.  

“As its measurements show, the Moon turned out to be a fairly ‘wet’ place: in certain areas, under a layer of dry soil from several tens of centimeters to one meter thick, the content of water ice can be up to 5% by weight of the soil, which is more than in the Sahara Desert on Earth,” the IKI RAS website explains.