Neutron Probes for the Construction and Resource Utilization eXplorer (CRUX)

The Construction and Resource Utilization eXplorer (CRUX) project is developing a flexible integrated suite of instruments with data fusion software and an executive controller for in situ regolith resource assessment and characterization. CRUX includes two neutron detectors, the Surface Neutron Probe (SNeuP) and the Borehole Neutron Probe (BNeuP) to help locate and assess potential hydrogen-bearing deposits at the lunar poles and on Mars. Carried on a rover, SNeuP locates near-surface water (or other hydrogenous volatiles) in a lightweight (481 g) package. BNeuP determines the stratigraphy of hydrogenous subsurface layers to depths of 10 meters (or more if an integrated neutron source is used) while operating within a drill string segment. It weighs 517 g, and consumes 2.25 W. The instruments' heritage includes the Lunar Prospector neutron spectrometer and numerous programmatic space instrument applications at Los Alamos. We have tested the SNeuP and BNeuP prototypes and have demonstrated their ability to detect near-surface hydrogenous materials. In a lunar or Mars exploration application the instruments could be passive, sounding materials through the detection of neutrons produced by cosmic ray spallation in soils and ice. However, in terrestrial field tests we have used a neutron source to `illuminate' surrounding materials and gauge the instruments' efficacy.