WCSAR-TR-AR3-9201-2 Lunar He-3 Mining: Improvements on the Design of the UW Mark II Lunar Miner [prepared for Space 92, The Third International Conference on Engineering, Construction, and Operations in Space, 31 May-4 June 1992, Denver CO]

One of the minor constituents of the solar wind which has been implanted in the lunar regolith over its several billion year history, is helium 3 (He-3), a rare isotope of helium which has two protons and a single neutron in its nucleus. Helium 3 is a potential fuel that can be used in near-aneutronic advanced nuclear fusion reactors for generating electric power on earth in a safe and environmentally clean way. Unfortunately He-3 is not available on earth. Although its existence on the moon is in a very dilute form, nevertheless, it can be shown that it is the only lunar resource which is worth bringing back to earth. Several methods have been proposed for mining lunar He-3, one being the roving lunar miner described in this paper. The Mark II miner excavates, beneficiates, processes and redeposits the lunar regolith while moving slowly across the lunar landscape on a charted path. This miner can obtain approximately 33 kg of He-3 in one year while operating during lunar days to take advantage of solar energy. During this time it covers one square kilometer, mining the surface to a depth of three meters. One of the most limiting factors in He-3 acquisition is beneficiating the lunar regolith down to particles smaller than 50 microns. In the original design, beneficiation down to the fine fraction took place in an electrostatic separator. An alternate method is to use a fluidizing stream of gas to separate a range of particles. A preliminary analysis of such a process is addressed in this paper. * Senior Scientist, Fusion Technology Institute, Nuclear Engineering and Engineering Physics Department and Wisconsin Center for Space Automation and Robotics, University of Wisconsin-Madison, Madison, WI, 53706-1687.