The Hyperspectral Thermal Emission Spectrometer (HyTES) is an airborne imaging spectrometer with 256 spectral channels between 7.5 and 12 micrometers in the thermal infrared part of the electromagnetic spectrum and 512 pixels cross-track. HyTES is being developed to support the Hyperspectral Infrared Imager (HyspIRI) mission. HyspIRI includes two instruments mounted on a satellite in Low Earth Orbit. There is an imaging spectrometer measuring from the visible to short wave infrared (VSWIR) and a multispectral thermal infrared (TIR) imager. The VSWIR and TIR instruments will both have a spatial resolution of 60 m at nadir. HyTES will provide the HyspIRI Group data at much higher spatial and spectral resolutions to help determine the optimum band positions for the HyspIRI-TIR instrument as well as provide precursor datasets for Earth Science research in the TIR. HyTES completed its first flights in July 2012.
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The Prototype HyspIRI Thermal Infrared Radiometer (PHyTIR) is being developed as part of the risk reduction activities associated with the Hyperspectral Infrared Imager (HyspIRI). The HyspIRI mission was recommended by the National Research Council Decadal Survey and includes a visible shortwave infrared (SWIR) pushboom spectrometer and a multispectral whiskbroom thermal infrared (TIR) imager. Data from the HyspIRI mission will be used to address key science questions related to the Solid Earth and Carbon Cycle and Ecosystems focus areas of the NASA Science Mission Directorate. The HyspIRI TIR system will have 60m ground resolution, better than 200mK noise equivalent delta temperature (NEDT), 0.5C absolute temperature resolution with a 5-day repeat from LEO orbit. PHyTIR addresses the technology readiness level (TRL) of certain key subsystems of the TIR imager, primarily the detector assembly and scanning mechanism. The PHyTIR focal plane (FPA) assembly consists of a Mercury Cadmium Telluride (MCT) detector array with a custom Read Out Integrated Circuit (ROIC) and a spectral filter assembly that defines each band. The FPA includes time delay integration. The custom ROIC provides a high speed readout enabling the high data rates needed for the 5 day repeat. PHyTIR also demonstrates a newly developed interferometeric metrology system. This system will provide an absolute measurement of the scanning mirror to an order of magnitude better than conventional optical encoders. This will minimize the reliance on ground control points hence minimizing post-processing (e.g. geo-rectification computations).