Title of Presentation: An IR Spectrometer for Mars Drill Operations
Primary (Corresponding) Author: William D. Smythe
Organization of Primary Author: NASA Jet Propulsion Laboratory
Co-Authors: M. Foote, E. Johnson, J. Daly, P.Loges,
Abstract: An infrared spectrometer suited for use during drilling has been implemented by integrating an Ion-Optics solid-state IR spectrometer, a Pulse-IR blackbody source and a microthermopile detector array developed by Marc Foote at JPL into a package to fit within a Honeybee Mars Drill design. The borehole IR spectrometer is used to monitor subsurface stratigraphy encountered throughout the drilling process. The spectrometer/IR combination is used in reflectance spectrometer mode to monitor H2O and CO2 content, as well as iron and carbonate mineralogies.
The solid state spectrometer uses the index of refraction of silicon to achieve the required dispersion in a small footprint. The package has low mass, with minimal requirements for a supporting structure and has most components are bonded into alignment to withstand launch and drilling loads. The original Ebert solid state spectrometer has been modified to fit within the spatial constraint of the drill segment diameter. Changes include using a Littrow layout (more compact) and stacking the grating and detector on planar part of the optical bench to conform better to the cylindrical geometry.
The illuminator is built a standard Ion Optics (Pulse-IR) infrared source with off-axis paraboloid concentrators. Illumination is a critical element for the borehole spectrometer, with the illumination and reflected signal sharing the same (small) window.
The spectrometer window is situated between fluting on the drill thus sampling cuttings near drill tip. This spectrometer will both speed operations and reduce risk in remote drilling operations by reducing the number of times the drill string must be extracted from the borehole.