Thermal Infrared Spectrometers for the Polar Radiant Energy in the Far-Infrared Experiment (PREFIRE)

The Polar Radiant Energy in the Far-InfraRed Experiment (PREFIRE) was selected by NASA to fly two miniaturized Thermal InfraRed Spectrometers (TIRS) capable of distinguishing the spectral signatures of surface and atmospheric properties in Earth's polar regions. A trade study examining spectral sampling as well as separation of cloudy and clear scenery at 20 km scales highlighted the possibility to utilize ambient (uncooled) detector technologies in a miniaturized spectrometer that could facilitate low-cost and rapid access to space. This work describes the design, implementation, testing and performance of two TIRS systems, as well as the challenges and acceptable limitations of the cost-constrained effort, that feature the novel joining of compact thermopile array technologies with concentric imaging spectrometry methods. The TIRS systems presented here each have 2.7 kg mass, draw 4.3 W power, and provide spectral resolution of 1.71 $\mu$m below 35 $\mu$m sampled at 0.86 $\mu$m increments.