Tricorder Tech: The Development and Demonstration of the Portable Acousto‐Optic Spectrometer for Astrobiology in Cave Environments
Planetary caves are desirable environments for the search for biosignatures corresponding to extant or extinct extraterrestrial life due to the protection they offer from surface-level solar radiation and ionizing particles.
Near-infrared (NIR) reflectance spectroscopy is one of a multitude of techniques that, when taken together, can provide a comprehensive understanding of the geomicrobiology in planetary subsurface regions.
To that end, we developed two portable NIR spectrometers that employ acousto-optic tunable filters and demonstrated them in three geochemically distinct cave environments. The instruments were deployed both as stand-alone spectrometers positioned against the targets manually and as a component of an instrument payload mounted on a quadruped robot capable of vertical excursions of several meters.
In situ measurements of calcium carbonates, sulfates, metal oxides, and microbial colonies and mats revealed spectral signatures that enable a distinction between the targets of interest and the underlying substrates.
The ruggedness and portability of the instruments, and their low size, weight, and power, spectral agility, and active illumination make AOTF-based spectrometers ideally suited for studies of planetary caves.
(a) Top-down view of the aluminum optical head that contains the acousto-optic tunable filter crystal and focusing optics. The optical head is affixed inside the stainless steel housing box with a sapphire window over the optical aperture. (b) Top-down view of the electronics box, which contains controllers for the main power, detector thermoelectric cooler, the RF synthesizer, and the lamp. (c) View of the electronics box as deployed in Fort Stanton Cave. The switches and boards are covered with a plastic sheet to protect them from dust and moisture, and the rugged case is equipped with desiccant (taped to the lid) to control the moisture level near the electronics. Photo courtesy of R. Hull. (d) The portable acousto-optic spectrometer for astrobiology instrument in operation. Four team members are managing the instrument control laptop (lower right), cables (upper right), electronics module (upper left), and the spectrometer module (lower left). The battery pack is being worn around the waist of one of the team members (upper left). Photo courtesy of W. Walker. — Earth and Space Science
The Development and Demonstration of the Portable Acousto‐Optic Spectrometer for Astrobiology in Cave Environments, Earth and Space Science (open access)
Astrobiology
