Search NASA⌕ Search

SEARCH · Search NASA

Results for “Spectrometer”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 577 records · Page 32
All sourcesNASA NTRSDOE OSTI
NASA NTRS1991

Remote sensing of Earth's atmosphere and surface using a digital array scanned interferometer: A new type of imaging spectrometer

The capabilities of the digital array scanned interferometer (DASI) class of instruments for measuring terrestrial radiation fields over the visible to mid-infrared are evaluated. DASI's are capable of high throughput, sensitivity and spectral resolution and have the potential for field-of-view spatial discrimination (an imaging spectrometer). The simplicity of design and operation of DASI's make them particularly suitable for field and airborne platform based remote sensing. The long term objective is to produce a versatile field instrument which may be applied toward a variety of atmospheric and surface studies. The operation of DASI and its advantages over other spectrometers are discussed.

Hammer, Philip D.↗
NASA NTRS1991

Advanced Solid-State Array Spectrometer (ASAS) data sets from the 1990 field season: A unique look at two forested ecosystems

The Advanced Solid-state Array Spectrometer (ASAS) is a pointable imaging spectrometer which uses a solid-state array to acquire imagery of terrestrial targets in 29 spectral bands from .4 to .8 microns. Performance and calibration of the instrument are described. The ASAS data sets obtained in 1990 provide a unique look at forest canopies from two different forest regions of the North America continent under varying temporal, spectral, and bidirectional conditions. These data sets will be used to study such parameters as the albedo of forest canopies, the dynamics of scene radiation due to factors such as canopy architecture, moisture stress, leaf chemistry, topography, and understory composition.

Walthall, Charles L.↗
NASA NTRS1991

Retrieval and molecule sensitivity studies for the global ozone monitoring experiment and the scanning imaging absorption spectrometer for atmospheric chartography

The Global Ozone Monitoring Experiment (GOME) and the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) are diode based spectrometers that will make atmospheric constituent and aerosol measurements from European satellite platforms beginning in the mid 1990's. GOME measures the atmosphere in the UV and visible in nadir scanning, while SCIAMACHY performs a combination of nadir, limb, and occultation measurements in the UV, visible, and infrared. A summary is presented of the sensitivity studies that were performed for SCIAMACHY measurements. As the GOME measurement capability is a subset of the SCIAMACHY measurement capability, the nadir, UV, and visible portion of the studies is shown to apply to GOME as well.

Chance, Kelly V.↗
NASA NTRS1990

Ion mass spectrometer measurements from the Space Shuttle

Ion-mass-spectrometer measurements made, as part of the University of Iowa's Plasma Diagnostic Package, on the STS-3 and Spacelab 2 missions, sampled a variety of positive ion composition perturbations in response to gas emissions from the vehicle. A background of contaminant ion species (mostly relating to water) always exists in the vicinity of the Shuttle. The measured number fluxes of the contaminant ions vary differently from those of the ambient ions in response to changes in the spectrometer and spacecraft angles of attack. There is a near-Shuttle wake cavity in the contaminant ion distributions which has a different spatial configuration than the wake of the ambient ions. Although water dumps produce the longest term ion perturbations, the most well defined effects were observed from measurements taken during the short firings of the reaction-control-system thrusters.

Grebowsky, J. M.↗
NASA NTRS1989

Recent advances in airborne terrestrial remote sensing with the NASA airborne visible/infrared imaging spectrometer (AVIRIS), airborne synthetic aperture radar (SAR), and thermal infrared multispectral scanner (TIMS)

Significant progress in terrestrial remote sensing from the air has been made with three NASA-developed sensors that collectively cover the solar-reflected, thermal infrared, and microwave regions of the electromagnetic spectrum. These sensors are the airborne visible/infrared imaging spectrometer (AVIRIS), the thermal infrared mapping spectrometer (TIMS) and the airborne synthetic aperture radar (SAR), respectively. AVIRIS and SAR underwent extensive in-flight engineering testing in 1987 and 1988 and are scheduled to become operational in 1989. TIMS has been in operation for several years. These sensors are described.

Vane, Gregg↗
NASA NTRS1990

Mapping alteration in the Goldfield Mining District, Nevada, with the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS)

Analysis of the data acquired by the Airborne Visible/IR Imaging Spectrometer over the Goldfield Mining District, Nevada, demonstrates the unique capabilities of high resolution imaging spectrometers for alteration mapping and identification of mineralogy. The study focuses on the 2-2.45 micron window, as alteration minerals of interest have their distinctive spectral reflectance features in this region. An attempt was made to map the spatial distribution of the individual minerals and produce a mixture maps showing their relative abundance on a pixel-by-pixel basis, focussing on selected subareas. Software and SNR performances limited success in detailed mapping.

Carrere, Veronique↗
NASA NTRS1990

Fiber-coupled high resolution infrared array spectrometer for the Kuiper Airborne Observatory

A novel cryogenic grating spectrometer (FCAS) is being designed for observations of volatiles in cometary and planetary atmospheres, and in newly forming planetary systems. The instrument features two-dimensional detector arrays coupled to a high-dispersion echelle by infrared fibers, and will achieve a spectral resolving power of about 40,000. The primary observational platform for this instrument will be the Kuiper Airborne Observatory, but it will also be configured for use at ground-based observatories. Initially, the spectrometer will use a 58 x 62, 1- to 5-micron InSb array. Larger-format IR arrays and arrays of different composition, will later be incorporated as they become available. The instrument will be used in two modes. The first uses a large format IR array in the spectral image plane for the customary one-dimensional spectral-one-dimensional spatial coverage. In the second mode, a massive, coherent bundle of infrared transmitting ZrF4 fibers will be installed after the dispersive element, to reformat the two-dimensional array into an elongated one-dimensional array for wide spectral coverage, allowing multiple lines to be measured in a single integration with high sensitivity. The overall instrument design is discussed, and the system sensitivity is estimated.

Glenar, D. A.↗
NASA NTRS1990

Miniaturized, 9-12 micron heterodyne spectrometer with space qualifiable design features

A demonstration-prototype CO2-laser heterodyne spectrometer operating at 9-12 microns and suitable for long-term space missions is described and illustrated with extensive diagrams, drawings, photographs, and graphs of test performance data. The spectrometer has total volume 0.63 cu m, mass 30 kg, and power requirement 60-70 W, compatible with miniature-class Space Shuttle experiment payload specifications. It comprises three modules: (1) an optical front end with reflecting optics, a 2-GHz BW HgCdTe photomixer, and a 0-2-GHz 40-dB RF preamplifier; (2) a local oscillator with an RF-excited waveguide CO2 laser, a 75-percent-efficiency RF amplifier, a stepper-driven grating mode selector, and an etalon stabilized for over 30,000 h of use; and (3) an RF-filter-bank spectral-line receiver with a 25-MHz RF channel, 1.6-GHz IF spectral coverage, onboard instrument control, a serial link to the host computer, and highly integrated design.

Glenar, D. A.↗
NASA NTRS1990

The Moderate Resolution Imaging Spectrometer-tilt (MODIS-T)

There will be several state-of-the-art spectrometers in operation on the NASA Polar Oribting Platform (NPOP-1) as part of the Earth Observing System. The Moderate Resolution Imaging Spectrometer (MODIS) will consist of two imaging spectroradiometric instruments, one nadir-viewing (MODIS-N) and the other tiltable (MODIS-T) for ocean observation and land bidirectional reflectance studies. The MODIS-T instrument is required to cover the wavelength range of 400 to 880 nm in approximately 15 steps, have less than 2.3 percent instrument-induced polarization, be calibrated to an absolute radiometric accuracy of at least 5 percent over the full dynamic range of the instrument, have a 1.1 kilometer square instantaneous field of view at nadir, and be capable of + or - 50-deg along-track tilt.

Magner, Thomas J.↗
NASA NTRS1991

Tunable far infrared laser spectrometers

The state of the art in far infrared (FIR) spectroscopy is reviewed. The development of tunable, coherent FIR radiation sources is discussed. Applications of tunable FIR laser spectrometers for measurement of rotational spectra and dipole moments of molecular ions and free radicals, vibration-rotation-tunneling spectra of weakly bound complexes, and vibration-rotation spectra of linear carbon clusters are presented. A detailed description of the Berkeley tunable FIR laser spectrometers is presented.

Blake, G. A.↗
NASA NTRS1991

The Voyager ultraviolet spectrometers - Astrophysical observations from the outer solar system

The main characteristics of the ultraviolet spectrometers on board the Voyager 1 and 2 spacecraft and the astrophysical experiments being currently conducted are reviewed. The spectrometers are sensitive over the wavelength range of 50 to 170 nm, which is observable only from space. The experiments include a program of stellar and nonstellar observations, monitoring of the ultraviolet flux from the sun, and studies of the interstellar wind entering the solar system. Several specific observations of particular interest are discussed.

Linick, S. H.↗
NASA NTRS1991

Combined Backscatter Moessbauer Spectrometer and X Ray Fluorescence analyzer (BaMS/XRF) for planetary surface materials

A backscatter Moessbauer spectrometer (BaMS) with included x ray fluorescence (XRF) capability for the Mars Environment Survey (MESUR) Mission, which has been proposed by NASA for 1998, is being developed. The instrument will also be suitable for other planetary missions such as those to the Moon, asteroids, and other solid solar-system objects. The BaMS would be unique for MESUR in providing information about iron mineralogy in rocks, clays, and other surface materials, including relative proportions of iron-bearing minerals. It requires no sample preparation and can identify all the normal oxidation states of iron (3+, 2+, 0). Thus, BaMS is diagnostic for weathering and other soil-forming processes. Backscatter design allows the addition of XRF elemental analysis with little or no modification. The BaMS/XRF instrument complements the thermal analyzer with evolved gas analyzer (TA-EGA) and the alpha-proton x-ray spectrometer (APXS) proposed (along with BaMS) for geochemical analysis on MESUR.

Agresti, D. G.↗
NASA NTRS1991

The rotating spectrometer: Biotechnology for cell separations

An instrument for biochemical studies, called the rotating spectrometer, separates previously inseparable cell cultures. The rotating spectrometer is intended for use in pharmacological studies which require fractional splitting of heterogeneous cell cultures based on cell morphology and swimming behavior. As a method to separate and concentrate cells in free solution, the rotating method requires active organism participation and can effectively split the large class of organisms known to form spontaneous patterns. Examples include the biochemical star, an organism called Tetrahymena pyriformis. Following focusing in a rotating frame, the separation is accomplished using different radial dependencies of concentrated algal and protozoan species. The focusing itself appears as concentric rings and arises from the coupling between swimming direction and Coriolis forces. A dense cut is taken at varying radii, and extraction is replenished at an inlet. Unlike standard separation and concentrating techniques such as filtration or centrifugation, the instrument is able to separate motile from immotile fractions. For a single pass, typical split efficiencies can reach 200 to 300 percent compared to the inlet concentration.

Noever, David A.↗
NASA NTRS1992

Sensitivity of LDEF foil analyses using ultra-low background germanium versus large NaI(T1) multidimensional spectrometers

Cobalt samples were analyzed for cosmic ray induced Co-60 with both an ultralow background germanium gamma ray spectrometer and with a large NaI(T1) multidimensional spectrometer using electronic anticoincidence shielding. Aluminum samples were analyzed for Na-22. The results are presented along with the relative sensitivities and precision afforded by the two methods.

Reeves, James H.↗
NASA NTRS1991

A spectrometer for studies of diffuse emission in the 900-1200 A band

A rich assortment of emission processes from the interstellar medium should generate complex spectra in the 900-1200-A regime. However, the detection of these lines is a difficult instrumental task since geocoronal and interplanetary airglow lines form an unwanted background requiring rejection by at least six orders of magnitudes. The design and performance are described of an imaging spectrometer. This spectrometer is designed for 2.5-A spectral resolution, low instrumental scattering, and a high sensitivity to diffuse emission.

Edelstein, J.↗
NASA NTRS1991

Improved Limb Atmospheric Spectrometer (ILAS) for polar stratospheric trace gas measurements

The Improved Limb Atmospheric Spectrometer (ILAS) is a grating spectrometer designed to measure vertical profiles of high latitude stratospheric constituents in a solar occultation mode. ILAS measurement gases are ozone (03), methane (CH4), nitrous oxide (N2O), nitric acid (HNO3), water vapor (H2O), nitrogen dioxide (NO2), and CFC-11 using an IR channel. Temperature, pressure, and aerosol are also measured using a visible channel. The IR channel consists of 44 detector elements which cover the spectral range 6.2 to 11.8 microns, and the visible channel is composed of 1024 pixels that cover 753 to 784 nm. ILAS will be installed on the Advanced Earth Observing Satellite (ADEOS) which will be launched in 1995. Instrument design data are outlined.

Yokota, Tatsuya↗
NASA NTRS1991

The application of high spectral and spatial resolution imaging spectrometers for locating downed aircraft

The utility of high-resolution imaging spectrometer data is examined as an aid in locating downed aircraft by using a unique spectral signature while not requiring the extremely high spatial resolution needed to identify an aircraft by shape. Ground spectral measurements of several airplane wings, overflight spectral measurements of aircraft scenes, and the rationale for the chosen spectral signature are presented. It is concluded that imaging spectrometers which can detect and spatially locate a narrow-band spectral signature filling only a few pixels appear to have a utility for search and rescue aircraft or satellite systems as a aid in locating small downed aircraft. This spectral feature would have to be added to the surface coatings applied to aircraft. Proposed for use as such a spectral signature is a significant negative reflectance slope, in the 520 to 580 nm interval.

Gatlin, James A.↗