Title: Mineral and Gas Identification Using a High-Performance Thermal Infrared Imaging Spectrometer
Author: Jeffrey Hall
Organization: The Aerospace Corporation
Co-Authors: David Gutierrez, Michael S. Ramsey, David M. Tratt, David W. Warren, Stephen J. Young
A novel multi-channel, thermal-band airborne imager to address HyspIRI-type measurement applications such as rock and soil identification, and volcano characterization and monitoring, is currently in the final year of development. The high-performance instrument, MAGI (Mineral And Gas Identifier), will use 32 bands covering the 7 to 12.7 micron region to both exceed the capabilities of existing thermal IR imagers and to enable additional missions, such as detection of gases from natural and anthropogenic sources. The higher spectral resolution, compared to existing thermal-infrared sensors, will improve discrimination of rock types, greatly expand the gas-detection capability, and result in more accurate land-surface temperature retrieval (important in evapotranspiration and drought studies). Data from The Aerospace Corporationís SEBASS sensor have been used to examine the trade-offs between spectral resolution, spectral range, area-coverage rate and instrument sensitivity. To maximize swath width, MAGI will use a whiskbroom scanner. The optical design for MAGI will incorporate a novel compact Dyson spectrometer mated to a high-frame-rate 2-D HgCdTe focal plane array. The Dyson spectrometer can operate at low f-numbers while still maintaining very small optical distortions. The optics and detector will be cooled by separate Stirling cryocoolers. Assembly and lab testing of the MAGI sensor will occur in the early summer timeframe with flight testing on a Twin Otter platform scheduled for August 2011. Comparison of data from these flights with data from ASTER and The Aerospace Corporationís Mako sensor will demonstrate the utility of this moderate spectral resolution sensor. Our program objectives include formulation of a concept for a space-based version of MAGI that would have a smaller pixel size and smaller NEDT than current sensors, thereby enabling smaller thermal changes to be tracked and smaller gas-emission sources to be monitored. It would include a field-splitting mirror and two-module design, thereby doubling the along-track field-of-view, and hence swath width, while halving the sensor revisit time.