Reducing the Size of the Borehole X-Ray Fluorescence Spectrometer (XRFS) Probe: Preliminary Design Study

摘要

This report describes the preliminary design effort for a borehole X- ray fluorescence spectroscopy (XRFS) instrument for the NASA Mars Subsurface Access Program. The original proposed design was 30 mm in diameter and was based on an existing terrestrial probe for analyzing heavy metal contaminants in soils. The new probe is intended to operate in conjunction with planetary drilling systems being developed for future missions in the next decade. Because the borehole will be pre-drilled, the new probe can be smaller than the existing probe and analyze a wider range of elements. The drills being developed may require excessive power consumption to drill a 30-mm diameter borehole, so a smaller diameter for the new XRFS probe would be a great advantage. This study was added to the project to investigate whether the new probe could be made smaller and to determine development costs for a smaller probe. A multi-pronged approach was taken to obtain as much information as possible for future plans and decisions. The design of the prototype XRFS probe being built under this project will not necessarily be changed by this study, but it is being undertaken early in the project so that as much information as possible can be included. The study began with a broad inquiry into the critical technologies for the components of the XRFS probe. The purpose was to find all appropriate components that were available off-the-shelf, to insure that no possible choices were overlooked, and to determine if any new developments were likely in the near future. Personal contacts of the APL-UW Principal Investigator (PI) and the NASA Technical Representative (TR) were employed to search for new vendors to manufacture these critical components and to discuss future developments with both familiar and new vendors. To broaden the investigation as much as possible, a formal search was made for potential vendors. A letter requesting information was sent to a large number of possible vendors.