Maturation of the Bulk Elemental Composition Analyzer (BECA) for Surface and Sub-surface Lunar Studies

The Bulk Elemental Composition Analyzer (BECA) is ideally suited to making high precision in situ measurements of the bulk elemental composition of the near-surface of the Moon. With no moving parts, BECA will provide bulk elemental composition information over a volume roughly 1m radius and 20 cm depth beneath the lunar surface without the need to touch the surface regolith. This powerful new BECA instrument will therefore be a highly useful tool for answering fundamental lunar science questions. BECA fills a special niche in that it measures the bulk composition of materials beneath the lunar surface and is thus less sensitive to effects of space weathering and other surface processes. BECA is especially versatile in application, with its ability to produce scientifically important information in both static lander and lunar rover configurations. BECA’s measurement of the local concentrations of both major and minor rock-forming elements such as H, O, Na, Mg, Al, Si, P, S, Cl, Ca, Ti, and Fe and the naturally radioactive elements (K, U and Th) will provide important geochemical constraints on the thermal and compositional evolution of the Moon. BECA can also answer outstanding science questions about lunar formation through its measurements of the distribution of lunar volatile elements at both polar and middle latitudes. In addition to these scientific contributions, BECA will also provide in situ ground truth validation for orbital composition maps obtained by multiple missions. Finally, BECA will also provide extremely useful information about near-surface resources important for future lunar exploration. BECA consists of a Pulsed Neutron Generator (PNG) which emits high energy neutrons that penetrate into the lunar subsurface and cause the materials to emit gamma rays with energies characteristic of the elements that produced them. BECA’s Gamma Ray Spectrometer (GRS) measures these gamma rays’ energies to identify the elements and the gamma ray line intensities to determine the quantity of the elements present. Low energy neutrons are also emitted by the lunar surface and measurements by BECA’s Neutron Detectors (NDs) allow for a more sensitive and deeper measurement of hydrogen than available from the gamma rays alone. BECA offers important science and resource detection capability for both static landers and rovers. Although the inclusion of the PNG dramatically increases its capabilities, BECA would provide important measurements on a static lander even without the PNG. The full BECA instrument is especially powerful for small rovers where it can make scientifically important elemental composition measurements for some elements in 15 minutes and complete composition measurements in about 2 hours. The BECA instrument currently contains components ranging from TRL 4 to TRL 9, thus its entering system TRL is 4. We propose to bring the individual components to TRL 6 and then test BECA in both a static lander and rover configuration to verify the maturation of the entire BECA instrument system to TRL 6 so that it is ready for both static lander and rover applications. We will verify BECA’s performance in both the static lander and small rover configurations at the Gamma ray Neutron Test (GNT) facility at NASA/GSFC. The static lander configuration will be tested by placing the BECA components on top of large, previously-assayed basalt and granite monuments and measuring their composition. The rover configuration will be tested by mounting the BECA components onto a small APL-developed rover. The rover would then drive over buried materials at the test site to demonstrate its capabilities for measuring variations in subsurface composition. This rover experiment will also allow us to develop operations procedures and quick turn-around analysis software so that the bulk elemental composition results from BECA can be used as part of the decision-making process for future lunar missions. More »