© 2011 California Institute of Technology. Government sponsorship acknowledged. Title: The Hyperspectral Thermal Emission Spectrometer (HyTES): preliminary results Author: Simon Hook Organization: Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California 91109 Co-Authors: William R. Johnson, Bjorn T. Eng, Sarath D. Gunapala, Andrew U. Lamborn, Pantazis Z. Mouroulis, Christopher G. Paine, Alexander Soibel, Daniel W. Wilson Abstract: The Hyperspectral Thermal Emission Spectrometer (HyTES) is being developed as part of the risk reduction activities associated with the Hyperspectral Infrared Imager (HyspIRI). HyspIRI is one of the Tier 2 Decadal Survey Missions. HyTES will provide information on how to place the filters on the HyspIRI Thermal Infrared Instrument (TIR) as well as provide antecedent science data. The pushbroom design has 512 spatial pixels over a 50- degree field of view and 256 spectral channels between 7.5μm to 12μm. HyTES includes many key enabling state-of-the-art technologies including a high performance convex diffraction grating, a quantum well infrared photodetector (QWIP) focal plane array, and a compact Dyson-inspired optical design. The Dyson optical design allows for a very compact and optically fast system (F/1.6). It also minimizes cooling requirements due to the fact it has a single monolithic prism-like grating design which allows baffling for stray light suppression. The monolithic configuration eases mechanical tolerancing requirements which are a concern since the complete optical assembly is operated at cryogenic temperatures (~100K). The QWIP allows for optimum spatial and spectral uniformity and provides adequate responsivity or D-star to allow 200mK noise equivalent temperature difference (NEDT) operation across the LWIR passband. Assembly of the system is nearly complete. After completion, alignment results will be presented which show low keystone and smile distortion. This is required to minimize spatial-spectral mixing between adjacent spectral channels and spatial positions. Predictions show the system will have adequate signal to noise for laboratory calibration targets. Introduction: The Jet Propulsion Laboratory (JPL) has a long history in developing science-grade imaging spectrometers for remote sensing applications. Examples include the Airborne Visible Infrared Imaging Spectrometer 1 (AVIRIS) and more recently a compact Offner type imaging spectrometer called the Moon Mineralogical Mapper 2 (M 3 ). The current effort involves completing the Hyperspectral Thermal Emission Spectrometer (HyTES) which is being developed under the NASA Instrument Incubator Program (IIP). HyTES brings together numerous in-house specialties such as optical design and general spectrometer alignment optimization, precision slit fabrication, high efficiency and low scatter concave diffraction grating design and fabrication, precision mechanical and machining capability and quantum well infrared photo detectors (QWIP) focal plane arrays. HyTES will operate between 7.5 and 12 µm. Spectral information from this wavelength range is extremely valuable for Earth Science research. The airborne instrument will be used in support of the HyspIRI mission. This mission was recommended by the National Research Council in their Earth Science Decadal Survey. The HyspIRI mission includes a visible shortwave infrared (SWIR) spectrometer and a