The Natural Radiation Background in a Lunar Lava Tube

Abstract

The recent announcements of evidence from the U.S. Grail satellite and from the Japanese SELENE (Kaguya) radar soundings of a possible lunar lava tube over 30 kilometers long have enhanced interest in exploiting lunar lava tubes for exploration and habitation. In a paper presented at ICES last year, Turner and Kunkel, 2017, examined the effectiveness of GCR shielding by the lunar regolith overburden covering a lunar lava tube, and found that less than 10 meter depth would reduce the radiation levels to terrestrial levels or lower. But a missing ingredient was the radiation levels produced by natural radionuclides in the walls of a lunar lava tube. This paper examines the possible range of natural (background) radiation levels from common radionuclides, including Thorium, Uranium, and Potassium expected to be present in lunar caves.