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NASA NTRSDate not supplied

CPF-VIIRS Intercalibration Methodology

NASA’s Climate Absolute Radiance and Refractivity Observatory (CLARREO) Pathfinder (CPF) mission will carry a high-accuracy reflected solar (RS) spectrometer to measure the Earth-reflected solar radiation from International Space Station with an SI-traceable radiometric uncertainty of 0.3% (1-sigma). The CPF measurements will serve as an on-orbit reference for intercalibrating other spaceflight RS instruments. The CPF intercalibration team has developed a state-of-the-art approach to calibrate the reflective solar bands (RSB) of the NOAA-20 Visible Infrared Imaging Radiometer Suite (VIIRS) sensor against the CPF benchmark measurements with an aimed intercalibration methodology uncertainty of 0.3%. This presentation will highlight the CPF mission overview and CPF-VIIRS intercalibration approach, as well as other potential outcomes of the CPF-VIIRS intercalibration study that may benefit the broader remote sensing community.

Raj Bhatt↗
NASA NTRS1972

Advances in pyroelectric infrared detectors.

Recent improvements in the pyroelectric detector have been due to the development of locked-in polarization, further reduction of the FET leakage current, and reduction of short circuit noise. The pyroelectric detector has been successfully employed in these typical applications: (1) thermograph using a single detector and X-Y scanner, (2) focal plane reticle scanner, (3) linear array thermal imaging system, (4) pyroelectric image tube, (5) radiometers (vertical temperature profile radiometer, carbon dioxide sensor), (6) high speed spectrometer, and (7) laser detector.

Beerman, H. P.↗
NASA NTRS1976

Zero-gravity growth of NaF-NaCl eutectics in the NASA Skylab program

Continuous and discontinuous NaF fibers, embedded in a NaCl matrix, were produced in space and on earth. The production of continuous fibers in a eutectic mixture is attributed to the absence of convection current in the liquid during solidification in space. Image transmission and optical transmittance measurements of transverse sections of the space-grown and earth-grown ingots were made with a light microscope and a spectrometer. It is shown that better optical properties were obtained from samples grown in space. This was attributed to a better alignment of NaF fibers along the ingot axis. A new concept is advanced to explain the phenomenon of transmittance versus far infrared wavelength of the directionally solidified NaCl-NaF eutectic in terms of the two-dimensional Bragg Scattering and the polarization effect of Rayleigh scattering. This concept can be applied to other eutectic systems as long as the index of refraction of the matrix over a range of wavelengths is known. Experimental data are in agreement with the theoretical prediction.

Yue, A. S.↗
NASA NTRS2012

Cryogenic Photogrammetry and Radiometry for the James Webb Space Telescope Microshutters

The James Webb Space Telescope (JWST) relies on several innovations to complete its five year mission. One vital technology is microshutters, the programmable field selectors that enable the Near Infrared Spectrometer (NIRSpec) to perform multi-object spectroscopy. Mission success depends on acquiring spectra from large numbers of galaxies by positioning shutter slits over faint targets. Precise selection of faint targets requires field selectors that are both high in contrast and stable in position. We have developed test facilities to evaluate microshutter contrast and alignment stability at their 35K operating temperature. These facilities used a novel application of image registration algorithms to obtain non-contact, sub-micron measurements in cryogenic conditions. The cryogenic motion of the shutters was successfully characterized. Optical results also demonstrated that shutter contrast far exceeds the NIRSpec requirements. Our test program has concluded with the delivery of a flight-qualified field selection subsystem to the NIRSpec bench.

Chambers, Victor J.↗
NASA NTRSDate not supplied

Composition and Density Stratification Observed by SuperCam in the First 300 Sols in Jezero Crater

The Perseverance rover has traveled > 2.5 km since leaving its Octavia Butler landing site in Jezero crater ~300 sols ago. The SuperCam remote sensing instrument suite has made > 1000 observations of bedrock along the traverse to provide a comprehensive picture of Jezero crater floor’s chemistry and mineralogy. SuperCam combines high resolution imaging, visible and near-infrared (VISIR) reflectance spectroscopy (0.4-0.85, 1.3-2.6 µm), remote time-resolved green-laser Raman and fluorescence spectroscopy, laser-induced breakdown spectroscopy (LIBS), and acoustic sensing into a single co-boresighted package [1, 2]. Derivation of the major element abundances as oxide wt% for this part of the mission is presented in [3], while calibration of the VIS and IR spectrometers are given in [4-7].

R.C. Wiens↗
NASA NTRS1977

Vesta - The first pyroxene band from new spectroscopic measurements

Spectral reflectance measurements of asteroid 4 Vesta were obtained using a silicon vidicon spectrometer with a resolution of 2 to 4 thousandths of a micron. A flow chart illustrating the data reduction procedure is given, and the location, absorptivity, and bandwidth of an absorption band detected in the near infrared region are described. The absorption band has been interpreted as due to electronic absorptions in ferrous iron in sixfold coordination in the pyroxene, pigeonite. The heightened spectral resolution obtained from the silicon vidicon imaging system permits determination of the relative calcium content of the pyroxene (10 to 12%). Furthermore, the symmetry of the absorption band implies an absence of olivine, which is commonly associated with pyroxene in terrestrial and meteoritic mineral samples. Support for these conclusions is found in spectral analyses of pyroxene, as well as in spectral reflectance measurements of 4 Vesta obtained by other observers.

Mcfadden, L. A.↗
NASA NTRS1979

Remote monitoring of the Gravelly Run thermal plume at Hopewell and the thermal plume at the Surry Nuclear Power Plant on the James River

On May 17, 1977, a remote sensing experiment was conducted on the James River, Virginia, whereby thermal spectrometer and near-infrared photography data of thermal discharges at Hopewell and the Surry nuclear power plant were obtained by an aircraft for one tidal cycle. These data were used in subsequent investigations into the near field discharge trajectories. For the Gravelly Run thermal plume at Hopewell, several empirical expressions for the plume centerline were evaluated by comparisons of the computed trajectories and those observed in the remote sensing images.

Talay, T. A.↗
NASA NTRS1998

Instrument for Achieving High Angular Resolution on the Infrared Telescope

Aberrations in stellar images caused by the atmosphere sets a significant limit on angular resolution in ground based astronomy. The largest of these aberrations is the image motion or wavefront tilt. Since the image motion is random it causes a blurring of the image, and this causes a blurring of the image from 0.3 arcseconds to about 0.7 arcseconds. The purpose of the tip-tilt project was to devise a system for the NASA Infrared Telescope Facility that would measure the image movement and correct it by rapidly tilting a mirror in two axes (tip and tilt). The system would involve building a CCD sensor package to measure the image motion, a new top end for the telescope to hold the tip-tilt mirror, a control system, and software. The system was designed to correct images for the facility camera, NSFCAM, and for the facility spectrometer, SPEX. Both of these instruments are equipped with a cold beamsplitter to feed the sensor package.

Hall, Donald N. B.↗
NASA NTRS2012

Instrumentation and First Results of the Reflected Solar Demonstration System for the Climate Absolute Radiance and Refractivity Observatory

The Climate Absolute Radiance and Refractivity Observatory (CLARREO) mission key goals include enabling observation of high accuracy long-term climate change trends, use of these observations to test and improve climate forecasts, and calibration of operational and research sensors. The spaceborne instrument suites include a reflected solar spectroradiometer, emitted infrared spectroradiometer, and radio occultation receivers. The requirement for the RS instrument is that derived reflectance must be traceable to Sl standards with an absolute uncertainty of <0.3% and the error budget that achieves this requirement is described in previo1L5 work. This work describes the Solar/Lunar Absolute Reflectance Imaging Spectroradiometer (SOLARIS), a calibration demonstration system for RS instrument, and presents initial calibration and characterization methods and results. SOLARIS is an Offner spectrometer with two separate focal planes each with its own entrance aperture and grating covering spectral ranges of 320-640, 600-2300 nm over a full field-of-view of 10 degrees with 0.27 milliradian sampling. Results from laboratory measurements including use of integrating spheres, transfer radiometers and spectral standards combined with field-based solar and lunar acquisitions are presented. These results will be used to assess the accuracy and repeatability of the radiometric and spectral characteristics of SOLARIS, which will be presented against the sensor-level requirements addressed in the CLARREO RS instrument error budget.

McCorkel, Joel↗
NASA NTRS2021

Railroad Valley Radiometric Calibration Test Site (RadCaTS) as Part of a Global Radiometric Calibration Network (RadCalNet)

The Radiometric Calibration Network (RadCalNet) is a coordinated multinational effort to provide in situ data that are suitable for the radiometric calibration and validation of Earth observation sensors that operate in the visible to shortwave infrared solar reflective spectral region (400 nm to 1000 nm). The main goals of RadCalNet are to provide top-of-atmosphere reflectance data to the scientific community, standardize data collection protocols for automated test sites, and to document the SI-traceable uncertainty budgets for each automated test site, of which there are currently four. The data available from RadCalNet are suitable for the calibration and validation of spaceborne imaging spectrometers. The work presented here provides a description of RadCalNet as well as a sample of the current results from the Radiometric Calibration Test Site (RadCaTS), which is located at Railroad Valley, Nevada, USA. Selected sensors for comparison include Terra and Aqua MODIS, SNPP and NOAA-20 VIIRS, and Sentinel-3A and -3B OLCI.

RadCalNet↗
NASA NTRS2005

Extracting Compositional Variation from THEMIS Data for Features with Large Topography on Mars Via Atmospheric Equalization

We have developed a means of equalizing the atmospheric signature in Mars Odyssey Thermal Emission Imaging System (THEMIS) infrared data over regions with large topography such as the Valles Marineris (VM). This equalization allows for the analysis of compositional variations in regions that previously have been difficult to study because of the large differences in atmospheric path length that result from large changes in surface elevation. Specifically, our motivation for this study is to examine deposits that are small at the scales observable by the Thermal Emission Spectrometer (TES) onboard Mars Global Surveyor, but which are more readily resolved with THEMIS.

Anderson, F. S.↗
NASA NTRS2018

Quantifying Methane Leak Emissions by Fused Airborne Imaging Spectroscopy with in Situ Surface Mobile and Airborne Observations of a California Producing Oil Field

Methane (CH4) emission budgets remain uncertain and are projected to grow as oil and gas production from short-lived wells increases and their subsequent transport through aging gas distribution networks. Orders-of-magnitude variations in temporal, spatial, and emission scales present a key challenge to leak detection and quantification. Also, the probability distributions for large and stochastic, leaky systems such as geological reservoirs (by natural migration-seeps) and petroleum production from those reservoirs remain largely unknown, needed to address current approach limitations. The scale of many petroleum systems favors remote sensing, but the sensitivity of such systems often precludes detection of weak emissions. Consequently, an accurate evaluation requires that the relative contribution from the emission "tails" of small leaks also be quantified, which is best carried out using high-sensitivity in situ methods. Fusion of remote sensing and in situ approaches leverages complementary capabilities to address these limitations. We show results from mobile surface (AMOG) and airborne in situ (AJAX) and thermal-infrared (TIR) hyperspectral imaging spectroscopy (Mako) data applied to a producing oil field in the California Central Valley near Bakersfield. AMOG is an automobile-based mobile lab that measures 13 trace gases, aerosol size distributions and vertical profiles, 3D winds and other meteorology, and atmospheric column measurements by solar spectroscopy at highway speeds. AJAX measures 5 trace gases and 3D winds at ~140 m/s. Mako is a broad-area TIR imaging spectrometer that can discriminate multiple gases present in each pixel acquired. In situ-derived, total field emissions were 31±16 Gg/yr CH4. This was compared with Mako-derived emissions from all plumes identified across the study site. We found that super-emitters were not the dominant emissions mode and the spatial pattern of plume locations from production infrastructure was correlated to geological structures.

Leifer, Ira↗
NASA NTRS1992

Lunar UV-visible-IR mapping interferometric spectrometer

Ultraviolet-visible-infrared mapping digital array scanned interferometers for lunar compositional surveys was developed. The research has defined a no-moving-parts, low-weight and low-power, high-throughput, and electronically adaptable digital array scanned interferometer that achieves measurement objectives encompassing and improving upon all the requirements defined by the LEXSWIG for lunar mineralogical investigation. In addition, LUMIS provides a new, important, ultraviolet spectral mapping, high-spatial-resolution line scan camera, and multispectral camera capabilities. An instrument configuration optimized for spectral mapping and imaging of the lunar surface and provide spectral results in support of the instrument design are described.

Smith, W. Hayden↗
NASA NTRSDate not supplied

Using Polarized PCRTM-Solar Model to Validate EMIT Surface Reflectance L2A Product

Using the vector linearized discrete ordinate radiative transfer model (VLIDORT), a multiple-scattering multi-layer scattering code, coupled with a fast principal component (PC) radiative transfer model (PCRTM), we can simulate hyperspectral radiation fields from visible to shortwave infrared (VSWIR), i.e., 250 nm to 2500 nm. Since only limited accurate line-by-line calculation using VLIDORT is needed, this coupled PCRTM-VLIDORT approach is very efficient for simulating hyperspectral VSWIR spectra. These simulations incorporate accurately defined optical properties (gas absorptions, molecular and aerosol/cloud particle scattering) and detailed surface reflectance inputs. In this study we used the current L2A products of the Earth Surface Mineral Dust Source Investigation (EMIT) imaging spectrometer as the inputs to PCRTM-VLIDORT to simulate EMIT spectra. Comparing the simulated spectra with EMIT measurements provides an efficient method to validate the current EMIT product.

Xiaozhen Xiong↗
NASA NTRS1992

AVIRIS study of Death Valley evaporite deposits using least-squares band-fitting methods

Minerals found in playa evaporite deposits reflect the chemically diverse origins of ground waters in arid regions. Recently, it was discovered that many playa minerals exhibit diagnostic visible and near-infrared (0.4-2.5 micron) absorption bands that provide a remote sensing basis for observing important compositional details of desert ground water systems. The study of such systems is relevant to understanding solute acquisition, transport, and fractionation processes that are active in the subsurface. Observations of playa evaporites may also be useful for monitoring the hydrologic response of desert basins to changing climatic conditions on regional and global scales. Ongoing work using Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) data to map evaporite minerals in the Death Valley salt pan is described. The AVIRIS data point to differences in inflow water chemistry in different parts of the Death Valley playa system and have led to the discovery of at least two new North American mineral occurrences. Seven segments of AVIRIS data were acquired over Death Valley on 31 July 1990, and were calibrated to reflectance by using the spectrum of a uniform area of alluvium near the salt pan. The calibrated data were subsequently analyzed by using least-squares spectral band-fitting methods, first described by Clark and others. In the band-fitting procedure, AVIRIS spectra are fit compared over selected wavelength intervals to a series of library reference spectra. Output images showing the degree of fit, band depth, and fit times the band depth are generated for each reference spectrum. The reference spectra used in the study included laboratory data for 35 pure evaporite spectra extracted from the AVIRIS image cube. Additional details of the band-fitting technique are provided by Clark and others elsewhere in this volume.

Crowley, J. K.↗
NASA NTRS2002

STS-109 Flight Day 3 Highlights

This footage from the third day of the STS-109 mission to service the Hubble Space Telescope (HST) begins with the grappling of the HST by the robotic arm of the Columbia Orbiter, operated by Mission Specialist Nancy Currie. During the grappling, numerous angles deliver close-up images of the telescope which appears to be in good shape despite many years in orbit around the Earth. Following the positioning of the HST on its berthing platform in the Shuttle bay, the robotic arm is used to perform an external survey of the telescope. Some cursory details are given about different equipment which will be installed on the HST including a replacement cooling system for the Near Infrared Camera Multi-Object Spectrometer (NICMOS) and the Advanced Camera for Surveys. Following the survey, there is footage of the retraction of both of the telescope's two flexible solar arrays, which was successful. These arrays will be replaced by rigid solar arrays with decreased surface area and increased performance.

Source record↗
NASA NTRS2013

Coordinated Analyses of Antarctic Sediments as Mars Analog Materials Using Reflectance Spectroscopy and Current Flight-Like Instruments for CheMin, SAM and MOMA

Coordinated analyses of mineralogy and chemistry of sediments from the Antarctic Dry Valleys illustrate how data obtained using flight-ready technology of current NASA and ESA missions can be combined for greater understanding of the samples. Mineralogy was measured by X-ray diffraction (XRD) and visible/ near-infrared (VNIR) reflectance spectroscopy. Chemical analyses utilized a quadrupole mass spectrometer (QMS) to perform pyrolysis-evolved gas analysis (EGA) and gas chromatography-mass spectrometry (GC/MS) both with and without derivatization, as well as laser desorption-mass spectrometry (LD/MS) techniques. These analyses are designed to demonstrate some of the capabilities of near-term landed Mars missions, to provide ground truthing of VNIR reflectance data acquired from orbit by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) on MRO and to provide detection limits for surface- operated instruments: the Chemistry and Mineralogy (CheMin) and Sample Analysis at Mars (SAM) instrument suites onboard Mars Science Laboratory (MSL) and the Mars Organic Molecule Analyzer (MOMA) onboard ExoMars-2018. The new data from this study are compared with previous analyses of the sediments performed with other techniques. Tremolite was found in the oxic region samples for the first time using the CheMin-like XRD instrument. The NIR spectral features of tremolite are consistent with those observed in these samples. Although the tremolite bands are weak in spectra of these samples, spectral features near 2.32 and 2.39 micrometers could be detected by CRISM if tremolite is present on the martian surface. Allophane was found to be a good match to weak NIR features at 1.37-1.41, 1.92, and 2.19 micrometers in spectra of the oxic region sediments and is a common component of immature volcanic soils. Biogenic methane was found to be associated with calcite in the oxic region samples by the SAM/EGA instrument and a phosphoric acid derivative was found in the anoxic region sample using the SAM/MTBSTFA technique.

Mars↗
NASA NTRS2006

Space-Based Near-Infrared CO2 Measurements: Testing the Orbiting Carbon Observatory Retrieval Algorithm and Validation Concept Using SCIAMACHY Observations over Park Falls, Wisconsin

Space-based measurements of reflected sunlight in the near-infrared (NIR) region promise to yield accurate and precise observations of the global distribution of atmospheric CO2. The Orbiting Carbon Observatory (OCO) is a future NASA mission, which will use this technique to measure the column-averaged dry air mole fraction of CO2 (XCO2) with the precision and accuracy needed to quantify CO2 sources and sinks on regional scales (approx.1000 x 1000 sq km and to characterize their variability on seasonal timescales. Here, we have used the OCO retrieval algorithm to retrieve XCO2 and surface pressure from space-based Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) measurements and from coincident ground-based Fourier transform spectrometer (FTS) measurements of the O2 A band at 0.76 mm and the 1.58 mm CO2 band for Park Falls,Wisconsin. Even after accounting for a systematic error in our representation of the O2 absorption cross sections, we still obtained a positive bias between SCIAMACHY and FTS XCO2 retrievals of approx.3.5%. Additionally, the retrieved surface pressures from SCIAMACHY systematically underestimate measurements of a calibrated pressure sensor at the FTS site. These findings lead us to speculate about inadequacies in the forward model of our retrieval algorithm. By assuming a 1% intensity offset in the O2 A band region for the SCIAMACHY XCO2 retrieval, we significantly improved the spectral fit and achieved better consistency between SCIAMACHY and FTS XCO2 retrievals. We compared the seasonal cycle of XCO2 at Park Falls from SCIAMACHY and FTS retrievals with calculations of the Model of Atmospheric Transport and Chemistry/Carnegie-Ames-Stanford Approach (MATCH/CASA) and found a good qualitative agreement but with MATCH/CASA underestimating the measured seasonal amplitude. Furthermore, since SCIAMACHY observations are similar in viewing geometry and spectral range to those of OCO, this study represents an important test of the OCO retrieval algorithm and validation concept using NIR spectra measured from space. Finally, we argue that significant improvements in precision and accuracy could be obtained from a dedicated CO2 instrument such as OCO, which has much higher spectral and spatial resolutions than SCIAMACHY. These measurements would then provide critical data for improving our understanding of the carbon cycle and carbon sources and sinks.

carbon dioxide↗