Demonstration of a portable AOTF IR spectrometer for in situ exploration of planetary surfaces

We discuss the development of a portable NIR reflectance point spectrometer based on acousto-optic tunable filter (AOTF) technology for future in situ geologic investigations of planetary surfaces. AOTFs are low power devices that operate on the principle of diffraction in a birefringent crystal. We have demonstrated the efficacy of this technique in extreme subterranean environments using the Portable AOTF Spectrometer for Astrobiology (PASA) to detect spectral biosignatures consistent with microbial alteration of geologic samples. PASA measures the IR reflectance spectrum of geologic samples in the 1.6 – 3.6 µm range with a resolution of λ/Δλ ≈ 250 – 400. We present the development and specifications of PASA, results from these expeditions, and discuss potential applications of a portable NIR point spectrometer based on AOTF technology for future landed or roving missions to other Solar System bodies.