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Retrieving surface properties from airborne hyperspectral imagery requires the use of an atmospheric correction model to compensate for atmospheric scattering and absorption. In this study, a solar spectral irradiance monitor (SSIM) from the University of Colorado Boulder was flown on a Twin Otter aircraft with the National Ecological Observatory Network’s (NEON) imaging spectrometer. Upwelling and downwelling irradiance observations from the SSIM were used as boundary conditions for the radiative transfer model used to atmospherically correct NEON imaging spectrometer data. Using simultaneous irradiance observations as boundary conditions removed the need to model the entire atmospheric column so that atmospheric correction required modeling only the atmosphere below the aircraft. For overcast conditions, incorporating SSIM observations into the atmospheric correction process reduced root-mean-square (rms) error in retrieved surface reflectance by up to 57% compared with a standard approach. In addition, upwelling irradiance measurements were used to produce an observation-based estimate of the adjacency effect. Under cloud-free conditions, this correction reduced the rms error of surface reflectance retrievals by up to 27% compared with retrievals that ignored adjacency effects.

Hyperspectral infrared measurements of Earth’s atmosphere from space have proven their value for weather forecasting, climate science and atmospheric composition. The CubeSat Infrared Atmospheric Sounder (CIRAS) instrument will demonstrate a fully functional infrared temperature, water vapor and carbon monoxide sounder in a CubeSat sized volume for at least an order of magnitude lower cost than legacy systems. Design for a CubeSat significantly reduces cost of access to space and enables flight in a constellation to reduce revisit time and enable new measurements including 3D winds. A technology demonstration of CIRAS is currently under development at JPL. The effort has completed integration and ambient testing of a high fidelity brassboard, complete with the flight configured optics assembly developed by Ball Aerospace with a JPL Immersion Grating and Black Silicon Entrance Slit. The brassboard includes a flight-configured High Operating Temperature Barrier Infrared Detector (HOT-BIRD) mounted in an Integrated Dewar Cryocooler Assembly (IDCA), enabling testing in the ambient environment. Ambient testing included radiometric testing of the system to characterize the instrument operability and NEdT. Spatial testing was performed to characterize the system line spread function (LSF) in two axes and report FWHM of the LSF. Spectral testing involved an air path test to characterize the spectral/spatial transformation matrix, and an etalon was used to measure the Spectral Response Functions (SRFs). Results of the testing show the CIRAS performs exceptionally well and meets the key performance required of the system. The end result of testing is the CIRAS instrument now meets TRL 4 with confidence in a brassboard configuration ready for thermal vacuum (TVac) testing necessary to achieve TRL 5 for the system.

Space imagery provides a unique resource for addressing environmental challenges associated with land cover change, land use, disaster relief, deforestation, regional planning and global change research. At Ball Aerospace, we are developing the Compact Hyperspectral Prism Spectrometer (CHPS) as a candidate imaging spectrometer technology for insertion into future Sustainable Land Imaging missions. The 2013 NRC report Landsat and Beyond: Sustaining and Enhancing the Nations Land Imaging Program recommended that the nation should “maintain a sustained, space-based, land-imaging program, while ensuring the continuity of 42-years of multispectral information.” In support of this, NASA’s Sustainable Land Imaging-Technology (SLI-T) program aims to develop technology for a new generation of smaller, more capable, less costly payloads that meet or exceed current Landsat imaging capabilities. CHPS is designed to meet these objectives, providing high-fidelity visible-to-shortwave spectroscopic information. CHPS supports continuity of legacy Landsat data products, but also, provides a path to enhanced capabilities in support of land, inland waters, and coastal waters science. CHPS features full aperture full optical path calibration, extremely low straylight, and low polarization sensitivity; all crucial performance parameters for achieving the demanding SLI measurement objectives. In support of our space-borne instrument development, we have developed an airborne instrument to provide representative spectroscopic data and data products. Now in the final year of this 3-year development program, we have completed our initial engineering airborne flights and are beginning science flights. We present initial results from laboratory characterization and calibration and from our engineering flights and close with an overview of instrument performance.

Ball Aerospace has developed CIRiS (Compact Infrared Radiometer in Space), a versatile multispectral, infraredimaging radiometer with on-orbit calibration capability. CIRiS generates images in three spectral bands between 7.5 um and 13.5 um. On-board calibration employs views to two flat-panel, high-emissivity carbon nanotube calibration sources and a third view to deep space. Image processing capabilities of the single electronics board include frame shifting and co-adding, binning and windowing, all with parameters selectable on orbit. An uncooled microbolometer focal plane enables CIRiS to operate without a cryocooler, thereby eliminating the associated power draw, complexity, and mission-life limitation. Total instrument power consumption measured in vacuum is < 10 Watts, including instrument heater power. A modular architecture that permits independent changes to CIRiS subsystems facilitates customization for Earth and planetary science missions. Constellations of 8 to 12 spacecraft carrying CIRiS instruments achieve global coverage from Low Earth Orbit (LEO) with daily revisit times, and varying spatial resolution. Among the potential Earth Science applications are measurements of evapotranspiration, plant health, volcano activity, sea surface and inland water body temperature, and vertical atmospheric profile of temperature and trace gas concentration. Lunar CIRiS, or “L-CIRiS” is a modified implementation for lunar surface mineralogy and thermophysical measurements from a lander or rover on the Moon’s surface. The present CIRiS flight model has completed all testing in preparation for an upcoming demonstration mission in LEO on a 6U CubeSat.

Ball’s Compact Hyperspectral Prism Spectrometer is being developed for technology insertion in the Sustainable Land Imaging (SLI) program. NASA’s SLI program aims to develop technologies for future Landsat-like measurements. In support of this, NASA’s SLI-Technology program aims to develop a new generation of smaller, more capable, less costly payloads that meet or exceed current Landsat imaging capabilities. By providing continuous visible-to-shortwave hyperspectral data, CHPS will support legacy Landsat data products as well as a much broader range of land science products. We discuss the development of the CHPS technology, initial performance test results, planned airborne demonstration and data distribution to science collaborators, and path to spaceborne demonstration.

The Compact Hyperspectral Prism Spectrometer is being developed as a candidate imaging spectrometer technology for insertion into future Sustainable Land Imaging missions. The 2013 NRC report Landsat and Beyond: Sustaining and Enhancing the Nations Land Imaging Program recommended that the nation should “maintain a sustained, space-based, land-imaging program, while ensuring the continuity of 42-years of multispectral information.” In support of this, NASA’s Sustainable Land Imaging-Technology program aims to develop a new generation of smaller, more capable, less costly payloads that meet or exceed current Landsat imaging capabilities. CHPS meets these objectives and will provide continuous visible-to-shortwave spectroscopic information at high spectral resolution. CHPS supports continuation of legacy Landsat data products as well as providing additional spectral information for a broader range of land science products. CHPS features full aperture full optical path calibration, exhibits high uniformity, extremely low straylight, and low polarization sensitivity. These are critical for meeting the demanding SLI measurement objectives. In preparation for space-borne instrument development, Ball is currently developing an airborne instrument that will provide representative spectroscopic data and data products. We are now in year 2 of a 3-year program and anticipate conducting initial airborne engineering flights in 4th-quarter 2018.

The Operational Landsat Imager (OLI) stray light performance was tested in 2010 in Ball’s stray light test facility. After the launch of OLI in 2013, measurements of on-orbit stray light performance confirmed the excellent pre-launch results. Ball is currently building OLI-2 for launch in 2020 and stray light testing was performed on the instrument in March 2018. This paper compares these measurements to OLI stray light test results and shows how they provide high confidence that OLI-2 will also provide excellent on-orbit stray light performance. Stray light performance of the two near identical builds is quite similar. This demonstrates the consistency of the assembly process and the repeatability of the testing performed in the Ball stray light test facility.

A wide variety of critical information regarding bioclimate, biodiversity, and biogeochemistry is embedded in airborne hyperspectral imagery. Most, if not all of the primary signal relies upon first deriving the surface reflectance of land cover and vegetation from measured hyperspectral radiance. This places stringent requirements on terrain, and atmospheric correction algorithms to accurately derive surface reflectance properties. An observatory designed to measure bioclimate, biodiversity, and biogeochemistry variables from surface reflectance must take great care in developing an approach which chooses algorithms with the highest accuracy, along with providing those algorithms with data necessary to describe the physical mechanisms that affect the measured at sensor radiance. Such an approach is in development with the Airborne Observation Platform (AOP) part of the National Ecological Observatory Network (NEON). NEON is a continental-scale ecological observation platform designed to collect and disseminate data to enable the understanding and forecasting of the impacts of climate change, land use change, and invasive species on ecology [1].

The National Ecological Observatory Network (NEON) will be the first observatory network of its kind designed to detect and enable forecasting of ecological change at continental scales over multiple decades. NEON will collect data at sites distributed at 20 ecoclimatic domains across the United States on the impacts of climate change, land use change, and invasive species on natural resources and biodiversity. The NEON Airborne Observation Platform (AOP) is an aircraft platform carrying remote sensing instrumentation designed to achieve sub-meter to meter scale ground resolution, bridging the scales from organisms and individual stands to satellite-based remote sensing. AOP instrumentation consists of a VIS/SWIR imaging spectrometer, a scanning small-footprint waveform LiDAR, and a high resolution airborne digital camera. AOP data will provide quantitative information on land use change and changes in ecological structure and chemistry including the presence and effects of invasive species. A Pathfinder Flight Campaign was conducted over a two week period during late August to early September 2010 in order to collect representative AOP data over one NEON domain site. NASA JPL flew the AVIRIS imaging spectrometer and NCALM flew an Optech Gemini waveform LiDAR over the University of Florida Ordway-Swisher Biological Station and Donaldson tree plantation near Gainesville Florida. The pathfinder data are discussed in detail along with how the data are being used for early algorithm and product development prototyping activities. The data collected during the campaign and prototype products are openly available to scientists to become more familiar with representative NEON AOP data.

Airborne remote sensing measurements provide the capability to quantitatively measure biochemical and biophysical properties of vegetation at regional scales, therefore complementing surface and satellite measurements. The National Ecological Observatory Network (NEON) will build three airborne systems to allow for routine coverage of NEON sites (60 sites nationally) and the capacity to respond to investigator requests for specific projects. Each airborne system will consist of an imaging spectrometer, waveform lidar and high-resolution digital camera. Remote sensing data gathered with this instrumentation needs to be quantitative and accurate in order to derive meaningful information about ecosystem properties and processes. Also, comprehensive and long-term ecological studies require these data to be comparable over time, between coexisting sensors and between generations of follow-on sensors. NEON's calibration plan for the airborne instrument suite relies on intensive laboratory, on-board, ground-based characterization as well as inter-sensor comparisons. As part of these efforts, NEON organized a pathfinder mission in September 2010 to test prototype techniques and procedures for field sampling and sensor validation. Imaging spectroscopy data from AVIRIS and waveform lidar data were acquired in addition to ecological field sampling at the Ordway-Swisher Biological Station near Gainesville, Florida. This paper presents NEON's capabilities for validation of at-sensor radiance of airborne and space-based sensors and shows results from the September 2010 pathfinder mission.

The National Ecological Observatory Network (NEON) is a planned facility of the National Science Foundation with the mission to enable understanding and forecasting of the impacts of climate change, land use change and invasive species on continental-scale ecology. Airborne remote sensing plays a critical role by providing measurements at the scale of individual shrubs and larger plants over hundreds of square kilometers. The NEON Airborne Observation Platform is designed to bridge scales from organism and stand scales, as captured by plot and tower observations, to the scale of satellite based remote sensing. Fused airborne spectroscopy and waveform LiDAR is used to quantify vegetation composition and structure. Panchromatic photography at better than 30 cm resolution will retrieve fine-scale information on land use, roads, impervious surfaces, and built structures. NEON will build three airborne systems to allow for regular coverage of NEON sites and the capacity to respond to investigator requests for specific projects. The system design achieves a balance between performance and development cost and risk, taking full advantage of existing commercial airborne LiDAR and camera components. To reduce risk during NEON construction, an imaging spectrometer design verification unit is being developed at the Jet Propulsion Laboratory to demonstrate that operational and performance requirements can be met. As part of this effort, NEON is also focusing on science algorithm development, computing hardware prototyping and early airborne test flights with similar technologies. This paper presents an overview of the development status of the NEON airborne instrumentation in the context of the NEON mission.

Airborne remote sensing plays a crucial role in the scaling strategy underpinning the National Ecological Observatory Network (NEON) design.12 Airborne spectroscopy will quantify plant species type and function, and waveform LiDAR will quantify vegetation structure and heterogeneity at the scale of individual shrubs and larger plants over hundreds of square kilometers. Digital imagery at better than 30 cm resolution will retrieve fine-scale information regarding land use, impervious surfaces, and built structures. NEON will operate three airborne systems to allow for routine coverage of NEON sites (60 sites nationally) and provide the capacity to respond to investigator requests for specific projects. The NEON system design achieves a balance between performance and development cost and risk, taking full advantage of existing commercial airborne LiDAR and camera components. Requirements for the imaging spectrometer require significant technology advancement. A pushbroom imaging spectrometer is under development to simultaneously achieve high spatial and spectral uniformity in response as well as high signal-to-noise ratio across a broad spectral range and over a wide field of view. To reduce risk during NEON construction, a spectrometer design verification unit is under development by the Jet Propulsion Laboratory to demonstrate that the design meets performance and operational requirements. Additional activities including algorithm development, computing hardware prototyping and early airborne test flights with similar technologies to reduce science data product development risk. Here we present an overview of system design, key requirements and development status of the NEON airborne instrumentation.

Airborne remote sensing plays a critical role in the scaling strategy underpinning the National Ecological Observatory Network (NEON) design. Airborne spectroscopy and waveform LiDAR will quantify plant species type and function, and vegetation structure and heterogeneity at the scale of individual shrubs and larger plants (1-3 meters) over hundreds of square kilometers. Panchromatic photography at better than 30 cm resolution will retrieve fine-scale information regarding land use, roads, impervious surfaces, and built structures. NEON will build three airborne systems to allow for routine coverage of NEON sites (60 sites nationally) and the capacity to respond to investigator requests for specific projects. The system design achieves a balance between performance, and development cost and risk. The approach takes full advantage of existing commercial airborne LiDAR and camera components. However, requirements for the spectrometer represent a significant advancement in technology. A pushbroom imaging spectrometer design is being proposed to simultaneously achieve high spatial, spectral and signal-to-noise ratio and a high degree of uniformity in response across wavelength and a wide field of view. To reduce risk during NEON construction, a spectrometer design verification unit is under development by the Jet Propulsion Laboratory to demonstrate that the design and component technologies meet operational and performance requirements. This paper presents an overview of system design, key requirements and development status of the NEON airborne instrumentation.

Airborne remote sensing provides the opportunity to quantitatively measure biochemical and biophysical properties of vegetation at regional scales, therefore complementing surface and satellite measurements. Next-generation programs are poised to advance ecological research and monitoring in the United States, the tropical regions of the globe, and to support future satellite missions. The Carnegie Institution will integrate a next generation imaging spectrometer with a waveform LiDAR into the Airborne Taxonomic Mapping System (AToMS) to identify the chemical, structural and taxonomic makeup of tropical forests at an unprecedented scale and detail. The NEON Airborne Observation Platform (AOP) is under development with similar technologies with a goal to provide long-term measurements of ecosystems across North America. The NASA Next Generation Airborne Visible/Infrared Imaging Spectrometer (AVIRISng) is also under development to address the science measurement requirements for both the NASA Earth Science Research and Analysis Program and the spaceborne NASA HyspIRI Mission. Carnegie AToMS, NEON AOP, and AVIRISng are being built by the Jet Propulsion Laboratory as a suite of instruments. We discuss the synergy between these programs and anticipated benefits to ecologists and decision-makers.

The National Ecological Observatory Network (NEON) Airborne Observation Platform (AOP) will fly an imaging spectrometer, small footprint waveform LiDAR and high-resolution digital camera to observe both the human drivers of climate change and the biological consequences of environmental change at a continental scale. The project is planned for a 30-year period. To be meaningful as an ecological climate data record, the AOP data set must have a continuous and consistent calibration effort. This paper briefly describes plans for the development of a robust calibration and validation plan to ensure data continuity from instrument-to-instrument, flight-to-flight, and year-toyear over the lifetime of the NEON project.

The National Ecological Observatory Network (NEON) is a continental-scale research platform for discovering, understanding and forecasting the impacts of climate change, land-use change, and invasive species on ecology. Site-based flux tower and field measurements will be coordinated with high resolution, regional airborne remote sensing observations. This data combined with satellite observations, national data sets and ecosystem models will extend site-based and regional coverage to the continental scale. The NEON Airborne Observation Platform (AOP) will carry remote sensing instrumentation designed to achieve sub-meter to meter scale ground resolution to bridge scales from organism and stand scales to the scale of satellite based remote sensing. The capability of the airborne system will be well beyond existing systems in its ability to produce quantitative information about ecosystem structure and functioning covering nearly 2 million hectares each year for 30 years or more.

The National Ecological Observatory Network (NEON) is an ecological observation platform for discovering, understanding and forecasting the impacts of climate change, land use change, and invasive species on continental-scale ecology. NEON will operate for 30 years and gather long-term data on ecological response changes and on feedbacks with the geosphere, hydrosphere, and atmosphere. Local ecological measurements at sites distributed within 20 ecoclimatic domains across the contiguous United States, Alaska, Hawaii, and Puerto Rico will be coordinated with high resolution, regional airborne remote sensing observations. The Airborne Observation Platform (AOP) is an aircraft platform carrying remote sensing instrumentation designed to achieve sub-meter to meter scale ground resolution, bridging scales from organisms and individual stands to satellite- based remote sensing. AOP instrumentation consists of a VIS/SWIR imaging spectrometer, a scanning small-footprint waveform LiDAR for 3-D canopy structure measurements and a high resolution airborne digital camera. AOP data will be openly available to scientists and will provide quantitative information on land use change and changes in ecological structure and chemistry including the presence and effects of invasive species. AOP science objectives, key mission requirements, and development status are presented including an overview of near-term risk-reduction and prototyping activities.

Ball Aerospace & Technologies Corp. (BATC) has added a powerful capability to its existing imaging spectrometer alignment and test facilities: Scanning Fabry-Perot source filters. These interferometers provide a means for efficient instrument testing with full characterization from the ultra-violet (UV) to longwave infrared (LWIR). Spectral Response Functions (SRF) and geometric distortions are accurately determined with a common approach. The techniques were demonstrated with a two band cryogenic LWIR spectrometer and with the mid-wave infrared (MWIR) Spaceborne InfraRed Atmospheric Sounder for Geosynchronous Earth Orbit (SIRAS-G) laboratory demonstration imaging spectrometer. The spectrometer testing and performance is presented.

The Spaceborne Infrared Sounder for Geosynchronous Earth Orbit (SIRAS-G) was developed by Ball Aerospace & Technologies Corp (BATC) under NASA’s 2002 Instrument Incubator Program. SIRAS-G was a technology development program focused on next-generation IR imaging spectrometers for sounding of the atmosphere. SIRAS-G demonstrated that the dispersive grating spectrometer is a suitable instrument architecture for this application. In addition to providing atmospheric temperature and water vapor profiles, SIRAS-G can provide trace gases concentrations, land and ocean surface temperatures and the IR mineral dust aerosol signature from satellite. The 3-year SIRAS-G IIP development effort included the successful cryogenic testing of the SIRAS-G laboratory demonstration spectrometer operating in the 2083 to 2994 cm -1 frequency range. The performance of the demonstration instrument has been quantified including measurement of keystone distortion, spectral smile, MTF, and the spectral response function (SRF). Development efforts associated with this advanced infrared spectrometer technology provides the basis for instrumentation to support future Earth science missions.

The Spaceborne Infrared Sounder for Geosynchronous Earth Orbit (SIRAS-G) was developed by Ball Aerospace and Technologies Corp (BATC) under NASA's 2002 Instrument Incubator Program. SIRAS-G is a technology development program focused on next-generation IR imaging spectrometers for sounding of the atmosphere. SIRAS-G is ideally suited for measuring atmospheric temperature and water vapor profiles, trace gases concentrations, land and ocean surface temperatures and the IR mineral dust aerosol signature from satellite, providing high-spectral resolution imaging spectroscopy over a broad IR spectral range and extended field of view. Instrument concepts for future mission in LEO and GEO are discussed, including an instrument concept to be flown in low earth orbit having the potential to provide high spatial resolution, comparable to that of MODIS, along with the high spectral resolution currently being demonstrated by the Atmospheric Infrared Sounder (AIRS). This capability would dramatically improve the yield of cloud-free pixels scenes that can be assimilated into Numerical Weather Prediction (NWP) models. The SIRAS-G dispersive spectrometer module is readily adaptable for missions in LEO, GEO and MEO orbits and can be optimized for spectral resolution over subsets of the total spectral range. We have completed the 3-year SIRAS-G IIP development effort, including successful testing of the SIRAS-G laboratory demonstration spectrometer that utilized the Hawaii 1RG MWIR FPA. Performance testing was conducted at cryogenic temperatures and the performance of the demo instrument has been quantified including measurement of keystone distortion, spectral smile, MTF, and the spectral response function (SRF) to high accuracy. We present the results of the laboratory instrument development including characterization of the demonstration instrument performance. We discuss instrument concepts utilizing SIRAS-G technology for potential future missions including an anticipated airborne flight demonstration.

] Globally significant amounts of atmospheric aerosolsand trace gases, including carbon monoxide (CO), areemitted from different types of biomass burning across theglobe ranging from human-induced burning of savanna andgrassland for agriculture and land-clearing to wildfires inboreal regions of the northern hemisphere. Biomass burningsmoke has adverse impacts on air quality and can affect theEarth’s radiative balance [Andreae et al., 1998]. Despite thegreat interest in the subject, quantifying the amount of gasesand particulates emitted from the burning of biomassremains a challenging problem. The challenges stem fromthe fact that amounts of CO and pyrogenic aerosols varystrongly depending on fuel type, oxygen availability, andburning phase. Chemical transport models (CTMs) capableof treating trace gases and aerosol particles are beingincreasingly used to improve our understanding of biomassburning emissions and transport [e.g., Heald et al., 2003].However, these models typically rely on bottoms-up emis-sion inventories with large uncertainties, assumptions onfuel type and burning efficiencies [Andreae and Merlet,2001], and on surface measurement networks with insuffi-cient coverage, particularly in the developing world. Giventhe inherent problems in ground-based measurements ofbiomass burning and a growing number of satellite sensorssuited to observing biomass burning emissions, it would bedesirable to utilize satellite remote sensing to the full extentpossible to improve our understanding of regional andglobal distributions of biomass burning aerosols and tracegases as well as their impacts.[

A small, low mass and low power imaging spectrometer for airborne remote sensing of atmospheric and surface properties called the prototype airborne visible imaging spectrometer (PAVIS) has been designed, constructed, and field-tested by the airborne sensors initiative team at Ball Aerospace & Technologies Corp. Originally a breadboard spectrometer, PAVIS was developed to validate in the laboratory that a large concave grating on a moderately aspheric surface with minimal scattering could be fabricated, and that both spectral and spatial performance could be optimized simultaneously. The airborne sensor is being developed to demonstrate that useful scientific data approaching the quality of AVIRIS and the MODIS airborne simulator whiskbroom scanning spectrometers can be obtained with a compact pushbroom imaging spectrometer.

SIRAS-G, developed under NASA’s 2002 IIP is enabling technology for future spaceborne IR sounders. A major aspect of this program was a laboratory demonstration dispersive spectrometer. Results from the demo instrument development program are described.

The impact of spectral channel registration errors in an imaging grating spectrometer on the retrieval of temperature and water vapor profiles in the presence of opaque, low-level (~700 mb) clouds is investigated.

We have developed a test method using parametric phase retrieval to estimate the wavefront of a cryogenic infrared spectrometer. The phase retrieval algorithm accounts for optical system obscurations, apodization, noisy detector pixels, polychromatic sources, and spectrometer dispersion. This tool was used in establishing the optimal alignment and focus for a two channel infrared spectrometer operating in a cryogenic environment. This paper provides an overview of the technique and test implementation.

The Spaceborne Infrared Atmospheric Sounder for Geosynchronous Earth Orbit (SIRAS-G) is an infrared imaging spectrometer concept being developed to address future Earth observation from both low-earth and geosynchronous orbit. SIRAS-G is now in its second year of development as part of NASA's Instrument Incubator Program. The SIRAS-G approach offers lower mass and power requirements than heritage instruments while offering enhanced capabilities for measuring atmospheric temperature, water vapor, and trace gas column abundances at improved spatial resolution. The system employs a wide field-of-view hyperspectral infrared optical system that splits the incoming radiation to several grating spectrometer channels. Combined with large 2-D focal planes, this system provides for simultaneous spectral and high-resolution spatial imaging. In 1999, the SIRAS team built and tested the SIRAS LWIR spectrometer also under NASA's Instrument Incubator Program (IIP-1). SIRAS-G builds on this experience with a goal of producing a laboratory demonstration instrument operating in the MWIR including the telescope, a single spectrometer channel, focal plane and active cooling subsystem. In this paper, we describe the on-going development of this instrument concept, focusing on aspects of the optical design, fabrication and testing of the demonstration instrument, performance requirement predictions and potential future scientific instrument applications.

BATC is developing the Spaceborne Atmospheric Infrared Sounder for Geosynchronous Earth Orbit (SIRAS-G) under NASA's 2002 Instrument Incubator Program. SIRAS-G represents a new approach to infrared imaging spectrometry suitable for Earth observation from geosynchronous orbit. SIRAS-G is an instrument concept with lower mass and power requirements than contemporary instruments that offers enhanced capabilities for measuring atmospheric temperature, water vapor, and trace gas column abundances in a compact package. In addition, the SIRAS-G concept is adaptable to airborne, low-Earth orbit and geosynchronous deployment. SIRAS-G employs a wide field-of-view hyperspectral infrared optical system that splits the incoming radiation to four separate grating spectrometer channels. Combined with large 2-D focal planes, this system provides simultaneous spectral and high-resolution spatial imaging designed to measure infrared radiation in 2048 spectral channels with a nominal spectral resolution (l/Dl) of between 700 and 1400. Design parameters and the associated basic design trades for a SIRAS-G laboratory demonstration instrument are presented in this paper. Results of completed instrument design analyses along with instrument performance predictions are included. Using these performance predictions, we offer a comparison of current technology with SIRAS-G's capabilities for measuring atmospheric temperature, water vapor profiles, and trace gas column abundances.

Satellite-based remote sensing offers the best opportunity for studying the properties of atmospheric aerosols and their radiative effects on the global scale over extended periods Tropospheric aerosols represent the largest uncertainty in predicting the radiative forcing of climate (IPCC, 2001). A key question is whether atmospheric aerosols contribute to warming or cool the climate system. Since the sign of direct radiative forcing is controlled by the ability of aerosol particles to absorb light, the information on the single scattering albedo of different aerosol types and its variations with aerosol lifecycles is clearly very desirable. Furthermore, the wavelength-dependent values of single scattering albedo from the UV to IR are important in retrieving aerosol optical depth from satellites passive remote sensing and for climate modeling. We describe the design of a space-borne polarimeter that was derived from the key science requirements. The performance of this candidate polarimeter, operating in the UV/VIS/NIR spectral regions, is described. The optical design form and various optical performance parameters, including transmittance calculations of the polarimeter’s spectral channels showing the “leakage” of polarization states, as well as the degree of polarization as function of wavelength and field of view are presented for the various wavelength regions. An overview of the instrument performance and driving operational parameters is presented.

A novel pushbroom sensor concept is introduced which incorporates a faceted field-condensing mirror to image the same ground pixel simultaneously in several spectral bands, while eliminating temporal misregistration and MTF smear due to earth rotation. This paper presents an overview of the instrument concept and the fabrication and performance details for the mirror.

The Spaceborne Infrared Sounder for Geosynchronous Earth Orbit (SIRAS-G) represents a new approach to infrared imaging spectrometry suitable for Earth observation from geosynchronous orbit. SIRAS-G is currently being developed under NASA’s Instrument Incubator Program (IIP-4). SIRAS-G is an instrument concept with lower mass and power requirements than heritage instruments that offers enhanced capabilities for measuring atmospheric temperature, water vapor, and trace gas column abundances in a compact package. The flight instrument concept measures infrared radiation in 2048 spectral channels with a nominal spectral resolution (λ/Δλ) of 1400. The system employs wide field-of-view hyperspectral infrared optical system that splits incoming radiation to four separate grating spectrometer channels. Combined with large 2-D focal planes, this system provides simultaneous spectral and high-resolution spatial imaging. In 1999, the SIRAS team built and tested the SIRAS LWIR Spectrometer (12.0 - 15.4μm) under NASA’s Instrument Incubator Program (IIP-1). SIRAS-G builds on this experience with a goal of producing a laboratory demonstration instrument including the telescope, a single spectrometer channel, focal plane and active cooling subsystem. In this paper, we describe the on-going development of this laboratory demonstration instrument, including design, performance requirement predictions, and potential future scientific instrument applications.

An instrument concept for an Imaging Multi-Order Fabry-Perot Spectrometer (IMOFPS) has been developed for measuring tropospheric carbon monoxide (CO) from space. The concept is based upon a correlation technique similar in nature to multi-order Fabry-Perot (FP) interferometer or gas filter radiometer techniques, which simultaneously measure atmospheric emission from several infrared vibration-rotation lines of CO. Correlation techniques provide a multiplex advantage for increased throughput, high spectral resolution and selectivity necessary for profiling tropospheric CO. Use of unconventional multilayer interference filter designs leads to improvement in CO spectral line correlation compared with the traditional FP multi-order technique, approaching the theoretical performance of gas filter correlation radiometry. In this implementation, however, the gas cell is replaced with a simple, robust solid interference filter. In addition to measuring CO, the correlation filter technique can be applied to measurements of other important gases such as carbon dioxide, nitrous oxide and methane. Imaging the scene onto a 2-D detector array enables a limited range of spectral sampling owing to the field-angle dependence of the filter transmission function. An innovative anamorphic optical system provides a relatively large instrument field-of-view for imaging along the orthogonal direction across the detector array. An important advantage of the IMOFPS concept is that it is a small, low mass and high spectral resolution spectrometer having no moving parts. A small, correlation spectrometer like IMOFPS would be well suited for global observations of CO2, CO, and CH4 from low Earth or regional observations from Geostationary orbit. A prototype instrument is in development for flight demonstration on an airborne platform with potential applications to atmospheric chemistry, wild fire and biomass burning, and chemical dispersion monitoring.

The Spaceborne Atmospheric Infrared Sounder for Geosynchronous Earth Orbit (SIRAS-G) represents a new approach to infrared imaging spectrometry suitable for Earth observation from geosynchronous orbit. SIRAS-G, selected for development under NASA’s 2002 Instrument Incubator Program, requires less mass and power than heritage instruments while offering enhanced capabilities for measuring atmospheric temperature, water vapor profiles, and trace gas column abundances in a compact package. The flight instrument concept measures infrared radiation in 2048 spectral channels with a nominal spectral resolution (Δλ/λ) of 1100. Combined with large 2-D focal planes, this system provides simultaneous spectral and high-resolution spatial imaging. In 1999, the SIRAS team built and tested the LWIR (12.0 - 15.4 μm) spectrometer under NASA’s Instrument Incubator Program (IIP-1999). SIRAS-G builds on this experience with a goal of producing and demonstrating the performance of a laboratory demonstration instrument. In this paper, we describe planned development activities and potential future scientific instrument applications.

The Spaceborne Atmospheric Infrared Sounder for Geosynchronous Earth Orbit (SIRAS -G) represents a new approach to imaging spectrometry in the infrared suitable for Earth observation from geosynchronous orbit. SIRAS - G, one of nine proposals selected for development under NASA's 2002 Instrument Incubator Program, focuses on the development of an instrument concept that requires less mass and power than heritage geosynchronous sounding instruments while offering enhanced capabilities for the measurement of atmospheric temperature, water vapor profiles, and trace gas column abundances. The SIRAS -G flight instrument concept measures infrared radiation in 2048 spectral channels with a nominal spectral resolution ( ��/�) of 1100. Combined with large area 2 -D focal planes, this system simultaneously provides both high -resolution spectral and spatial imaging. In 1999, the SIRAS team built and tested the LWIR (12.0 - 15.4 ∝m) SIRAS spectrometer under NASA's Instrument Incubator Program (IIP -1999). SIRAS -G builds on this experience with a goal of producing and demonst rating a laboratory prototype instrument. In this paper, we describe planned development activities and potential future scientific instrument applications for this instrument concept.

The performance, development and testing of the prototype spectrometer are discussed as well as potential applications for future missions.

Spatial and Temporal Scaling in Continental-Scale Ecology Workshop; Boulder, Colorado, 11–12 June 2012 Understanding the functional response of ecosystems across multiple spatial and temporal scales is one of the fundamental challenges in ecology. More than 50 researchers attended a June workshop focused on scaling ecological data from local and regional scales to the continental scale hosted by the National Ecological Observatory Network (NEON). The workshop addressed key issues associated with the influence of scale on the interpretation of ecological variation, particularly in the context of continental-scale terrestrial ecology. These questions are particularly relevant to NEON, the first ecological observation platform designed to assess the natural and human causes and the biological consequences of environmental change at large scales.

Near-field scattered light, due to ghost images produced from multiple reflections or due to scatter off optical surfaces, will contribute to background noise. This background noise can reduce contrast and blur edge transitions. These sources of background noise cannot be compensated for since they are scene-dependent. High-performance remote sensing instruments, such as the Moderate Resolution Imaging Spectrometer (MODIS), have strict systems-level radiometric performance criteria, such as transient response and stray light, which demand that background noise sources be well controlled. This paper discusses design challenges brought on by these requirements and subsequent modifications and analysis techniques used to minimize ghosting for the MODIS instrument.

A wide-field ultraviolet lens was developed under a contract from the Massachusetts Institute of Technology Center For Space Research in support of the NASA High Energy Transient Experiment (HETE). This 35 mm f/2.5 seven element lens operates over a broad portion of the near-ultraviolet spectrum and over a 52 degree field of view. Operation at cryogenic temperatures required that the lens system exhibit minimal change in focus with temperature. Aluminum was selected as the lens barrel material based on athermalization issues and the desire to minimize weight. Elastomeric bonding of elements into subcells was used for assembly along with a single adjustable airspace to compensate for tolerances.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The U.S. Navy has several hundred P3 Orion Aircraft which utilize the AN/AAS-36 Texas Instruments FLIRs. The system is an 8 - 12 micrometers long wave IR imaging system using a linear HgCdTe detector array. The FLIR optics consists of the classic common module imager which is a 3-element IR lens with an external scan mirror which produces the linear pushbroom scan over the linear detector array. This system is actually a dual field of view, and a 3-element Galilean afocal telescope located in front of the imager is used for a 3X magnification. In the wide field of view mode the imager is simply used alone looking out into object space, with the 3X afocal telescope rotated with its optical axis orthogonal to the imager axis. In order to switch to the narrow field of view, the afocal telescope is rotated 90 degree(s) and the user acquires a net 3X magnification to the imagery. The loss of imagery during the field switching operation has always been seen as a problem, and it would be far more desirable to have a continuously varying magnification instead. For this reason, the Navy put out a Small Business Innovation Research solicitation in 1989 with the intent of developing a continuously varying IR zoom lens to retrofit into onto the TI FLIR. OPTICS 1, Inc. completed Phase I of this SBIR which demonstrated feasibility of the design concept, and we have been under contract on the Phase II program since April, 1990.© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Much has been written in the past four to five years on the application of hybrid refractive/diffractive elements in infrared optical design. We are now beginning to see several excellent examples of actual systems which utilize such components. Little has been written, however, on the use of hybrid elements in lens systems for staring focal plane arrays which require 100% cold stop efficiency (CSE). Most designs presented in the literature have been for uncooled staring arrays. The purpose of this paper is to examine the requirements that present MWIR focal plane arrays (FPAs) place on the objective, and to investigate the role hybrid diffractive optical elements (DOEs) play in the solution of this imaging problem. We briefly examine the requirements imposed by the next generation MWIR FPAs to show that hybrids can play a role in compact, lightweight systems of the future. In addition, we illustrate areas of future design activity such as passively athermal IR objectives and wide angle IR lenses.

A laser diode collimator objective was developed in support of the Direct Detection Transceiver program. Close attention to optomechanical design issues including athermalization, alignment, selection of materials, mounting of elements, and hermetic sealing of the assembly was necessary to insure that the desired optical performance was maintained in space deployment.