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All sourcesNASA NTRSDOE OSTI
NASA NTRS2011

Visible and Near-IR Reflectance Spectra of Mars Analogue Materials Under Arid Conditions for Interpretation of Martian Surface Mineralogy

Visible and near-IR (VNIR) spectra from the hyper-spectral imagers MRO-CRISM and Mars Express OMEGA in martian orbit have signatures from Fe-bearing phases (e.g., olivine, pyroxene, and jarosite), H2O/OH-bearing phases (e.g., smectites and other phyllosilicates, sulfates, and high-SiO2 phases), and carbonate [e.g., 1-5]. Mineralogical assignments of martian spectral features are made on the basis of VNIR spectra acquired in the laboratory under appropriate environmental conditions on samples whose mineralogical composition is known. We report here additional results for our ongoing project [6] to acquire VNIR spectra under arid conditions.

Morris, R. V.↗
NASA NTRS1987

Deconvolution of spectra for intimate mixtures

Visible to near infrared reflectance spectra of macroscopic mixtures have been shown to be linear combinations of the reflections of the pure mineral components in the mixture. However, for microscopic mixtures the mixing systematics are in general nonlinear. The systematics may be linearized by conversion of reflectance to single scattering albedo (w), where the equations which relate reflectance to w depend on the method of data collection. Several proposed mixing models may be used to estimate mineral abundances from the reflectance spectra of intimate mixtures. These models are summarized and a revised model is presented. A noniterative (linear) least squares approach was used for curve fitting and the data, measured as bi-directional reflectance with incidence and emergence angles of 30 and 0 deg were converted to w by a simplified version of Hapke's equation for bi-directional reflectance. This model was tested with two mixture series composed of 45 to 75 micron particles: an anorthite-enstatite series and an olivine-magnetite series. The data indicate that the simplified Hapke's equation may be used to convolve reflectance spectra into mineral abundances if appropriate endmembers are known or derived from other techniques. For surfaces that contain a significant component of very low albedo material, a somewhat modified version of this technique will need to be developed. Since the abundances are calculated using a noniterative approach, the application of this method is especially efficient for large spectral data sets, such as those produced by mapping spectrometers.

Mustard, John F.↗
NASA NTRS1971

Visible and near-ultraviolet spectra of low-pressure rare-gas microwave discharges

The spectral emission characteristics of three commercial low pressure rare gas discharge lamps wire obtained in the near ultraviolet and visible wavelength range. All three lamps show a definite continuum over the entire wavelength range from 0.185 to 0.6 micrometers. Considerable line emission is superimposed on much of the continuum for wavelengths greater than 0.35 micrometers. These sources were used to make transmittance measurements on quartz samples in the near ultraviolet wavelength range.

Campbell, J. P.↗
NASA NTRS1993

Comparison of visible and near-infrared reflectance spectra of CM2 carbonaceous chondrites and primitive asteroids

Spectra of primitive asteroids (defined as C, P, and D classes and associated subclasses) were compared to the limited number of spectra of CM2 carbonaceous chondrites. An absorption feature located at 0.7 microns attributed to an Fe(+2) - Fe(+3) charge transfer absorption in iron oxides in phyllosilicates is apparent in some of the CM2 carbonaceous chondrite spectra and many of the asteroid spectra. Sawyer found a correlation between the area of the 0.7 micron feature and the mean semimajor axis of the asteroids. Spectra of a larger sample of carbonaceous chondrites, including 7 CM2 chondrites, covering a spectral interval of 0.30-2.5 microns were recently obtained using the Relab instrument at Brown University. These spectra were compared with spectrophotometric asteroid observations in a separate abstract. Those spectra of CM2 chondrites were isolated into the UV, visible and near-infrared spectral regions in order to compare them with high-quality narrowband reflectance spectra.

Vilas, F.↗
NASA NTRS2001

Effects of Palagonitic Dust Coatings on Visible, Near-IR, and Mossbauer Spectra of Rocks and Minerals: Implication for Mineralogical Remote Sensing of Mars

Visible, near-IR, and Mossbauer measurements on dust coated rocks and minerals show that a 300 5m thick layer is required to obscure the substrate for VNIR measurements and that a greater than 2000-micron-thick layer is required to obscure the substrate for Mossbauer measurements. Additional information is contained in the original extended abstract.

Morris, R.↗
NASA NTRS1982

Spectral characteristics of the iron oxides with application to the Martian bright region mineralogy

Reflectance spectra of eight polymorphs of FeOOH and Fe2O3 are determined in order to clarify the nature and significance of the iron oxide mineralogy on Mars. The effect of other components that might interfere with iron oxide absorption features is qualitatively constrained through the use of the Kebulka-Munk theory. It is found that the effect of temperature complicates the identification of a given Fe(3+) phase based on the position of the 6A1-4T1 absorption feature. While the Fe(3+) crystal field transitions are spin forbidden, most of the iron oxide polymorphs exhibit anomalously intense crystal field absorption features due to magnetic coupling between adjacent FeO6 octahedra. It is suggested that the resulting deviations from observed remotely sensed reflectance spectra of Mars may provide a basis for the exclusion of many iron oxide phases as significant components of the Martian Fe(3+) mineralogy. A comparison of these results with the visible region spectra of Martian bright regions indicates that the predominant Fe(3+)-bearing phase may be a magnetically disordered material, such as amorphous gels, some ferric sulphates, and other minerals in which Fe(3+) ions in the crystal structure are not magnetically coupled.

Sherman, D. M.↗
NASA NTRS1988

Spatial variations of the 3-micron emission features within Orion's Bar

3-micron spectra of the Orion Bar region have been obtained at three positions corresponding to different distances from the exciting source. The recently discovered unidentified features at 3.46, 3.51, and 3.57 microns are clearly visible. The spectra show that the 3.4 and 3.51-micron emission features increase in intensity relative to the strong 3.3-micron feature as the distance from the exciting source increases. The implications for polycyclic aromatic hydrocarbons and recent ideas concerning their ultraviolet excitation and spatial evolution are discussed.

Moorhouse, A.↗
NASA NTRS1979

Reflectance spectra for 277 asteroids

Visible and near-infrared reflectance spectra are presented for 277 asteroids. These represent the results of an 8-yr program and constitute all spectra available in 1979. There are approximately 80 recognizably different spectral types among the asteroids surveyed. Relatively few of these can be explained as mixtures of C- and S-type materials on individual asteroids, although Eos family members may be an exception.

Chapman, C. R.↗
NASA NTRS2009

Visible and Near-IR Reflectance Spectra for Smectite, Sulfate And Perchlorate under Dry Conditions for Interpretation of Martian Surface Mineralogy

Visible and near-IR (VNIR) spectral data for the martian surface obtained from orbit by the MRO-CRISM and OMEGA instruments are interpreted as having spectral signatures of H2O/OH-bearing phases, including smectites and other phyllosilicates, sulfates, and high-SiO2 phases [e.g., 1-4]. Interpretations of martian spectral signatures are based on and constrained by spectra that are obtained in the laboratory on samples with known mineralogical compositions and other physicochemical characteristics under, as appropriate, Mars-like environmental conditions (e.g., temperature, pressure, and humidity). With respect to environmental conditions, differences in the absolute concentration of atmospheric H2O can effect the hydration state and therefore the spectra signatures of smectite phyllosilicates (solvation H2O) and certain sulfates (hydration H2O) [e.g., 5-7]. We report VNIR spectral data acquired under humid (laboratory air) and dry (dry N2 gas) environments for two natural smectites (nontronite API-33A and saponite SapCa-1) to characterize the effect of solvation H2O on spectral properties. We also report spectral data for the thermal dehydration products of (1) melanterite (FeSO4.7H2O) in both air and dry N2 gas and (2) Mg-perchlorate (Mg(ClO4)2.6H2O) in dry N2 environments. Spectral measurements for samples dehydrated in dry N2 were made without exposing them to humid laboratory air.

Morris, R.V.↗
NASA NTRS1990

Combined infrared and ultraviolet-visible spectroscopy matrix-isolated carbon vapor

Infrared and UV-visible absorption spectra have been measured on the same sample of matrix-isolated carbon vapor in order to establish correlations between absorption intensities of vibrational and electronic transitions as a function of sample annealing. A high degree of correlation has been found between the IR feature at 1998/cm recently assigned to C8 and a UV absorption feature at about 3100 A. Thus, for the first time, direct evidence is given for the assignment of one of the unknown UV-visible features of the long-studied matrix-isolated carbon vapor spectrum.

Kurtz, Joe↗
NASA NTRS1985

Hibonite: Crystal Chemistry and Origin of Blue Coloration in Meteoritic Assemblages

The blue color and optical spectra of hibonite, a common constituent of refractory inclusions in carbonaceous chondrites, are discussed. Because they may be manifestations of exotic cation species stabilized in unusual coordination sites in the hibonite crystalstructure. Hibonite, ideally CaAl12O19, is conducive to atomic substitution of host Ca2+ and Al3+ ions by a variety of lanthanide and first series transition elements. The latter cations are responsible for the colors of many rock-forming minerals as a result of intraelectronic or intervalence transitions. The visible-region spectra of most oxide and silicate minerals are generally well understood. Assignments of absorption bands in meteoritic hibonite optical spectra due to uncertainties of cation valencies and complexities in the crystal structure are examined. The crystal chemistry of hibonite is reviewed, Mossbauer spectral measurements of iron-bearing hibonite and electronic transitions that may be responsible for the blue coloration of meteoritic hibonites are discussed.

Burns, R. G.↗
NASA NTRS1982

Do comets evolve into asteroids - Evidence from physical studies

Physical observations of low-activity periodic comets and asteroids in distant and peculiar orbits are reviewed. In particular, magnitude studies and reflection spectra at visible and infrared wavelengths are discussed. While it may never be possible to prove unambiguously that a cometary nucleus has been observed, the fainter a given comet is, the more likely it is that some light reflected from a solid surface will be observed. Studies of magnitudes obtained by Roemer suggest that at certain periods the nuclei of P/Arend-Rigaux and P/Neujmin 1 may be photometrically resolved. It is shown that this may also be the case for P/Schwassmann-Wachmann 1, but that it is less likely for P/Tempel 2. At times of minimum activity, the optical spectra of P/Arend-Rigaux and P/Schwassmann-Wachmann 1 resemble those of RD-type asteroids like 944 Hidalgo. In order to progress with physical studies of cometary nuclei, an increased effort should be made to obtain magnitudes and other physical observations of comets during stages of minimal activity.

Degewij, J.↗
NASA NTRS2004

Lunar and Planetary Science XXXV: Asteroids, Meteors, Comets

Reports included:Long Term Stability of Mars Trojans; Horseshoe Asteroids and Quasi-satellites in Earth-like Orbits; Effect of Roughness on Visible Reflectance Spectra of Planetary Surface; SUBARU Spectroscopy of Asteroid (832) Karin; Determining Time Scale of Space Weathering; Change of Asteroid Reflectance Spectra by Space Weathering: Pulse Laser Irradiation on Meteorite Samples; Reflectance Spectra of CM2 Chondrite Mighei Irradiated with Pulsed Laser and Implications for Low-Albedo Asteroids and Martian Moons; Meteorite Porosities and Densities: A Review of Trends in the Data; Small Craters in the Inner Solar System: Primaries or Secondaries or Both?; Generation of an Ordinary-Chondrite Regolith by Repetitive Impact; Asteroid Modal Mineralogy Using Hapke Mixing Models: Validation with HED Meteorites; Particle Size Effect in X-Ray Fluorescence at a Large Phase Angle: Importance on Elemental Analysis of Asteroid Eros (433); An Investigation into Solar Wind Depletion of Sulfur in Troilite; Photometric Behaviour Dependent on Solar Phase Angle and Physical Characteristics of Binary Near-Earth-Asteroid (65803) 1996 GT; Spectroscopic Observations of Asteroid 4 Vesta from 1.9 to 3.5 micron: Evidence of Hydrated and/or Hydroxylated Minerals; Multi-Wavelength Observations of Asteroid 2100 Ra-Shalom: Visible, Infrared, and Thermal Spectroscopy Results; New Peculiarities of Cometary Outburst Activity; Preliminary Shape Modeling for the Asteroid (25143) Itokawa, AMICA of Hayabusa Mission; Scientific Capability of MINERVA Rover in Hayabusa Asteroid Mission; Characteristics and Current Status of Near Infrared Spectrometer for Hayabusa Mission; Sampling Strategy and Curation Plan of Hayabusa Asteroid Sample Return Mission; Visible/Near-Infrared Spectral Properties of MUSES C Target Asteroid 25143 Itokawa; Calibration of the NEAR XRS Solar Monitor; Modeling Mosaic Degradation of X-Ray Measurements of 433 Eros by NEAR-Shoemaker; Scattered Light Remediation and Recalibration of near Sheomaker s NIS Global Dataaset at 433 Eros; Evaluation of Preparation and Measuring Techniques for Interplanetary Dust Particles for the MIDAS Experiment on Rosetta; Chiron: a Proposed Remote Sensing Prompt Gamma Ray Activation Analysis Instrument for a Nuclear Powered Prometheus Mission;From Present Surveying to Future Prospecting of the Asteroid Belt; Asteroid Physical Properties Probe Microgravity Testing of a Surface Sampling System for Sample Return from Small Solar System Bodies;and Penetrator Coring Apparatus for Cometary Surfaces.

Source record↗
NASA NTRS2004

Optimal Aerosol Parameterization for Remote Sensing Retrievals

We have developed a new algorithm for the retrieval of aerosol and gases from SAGE It1 solar transmission measurements. This algorithm improves upon the NASA operational algorithm in several key aspects, including solving the problem non-linearly and incorporating a new methodology for separating the contribution of aerosols and gases. In order to extract aerosol information we have built a huge database of aerosol models for both stratospheric and tropospheric aerosols, and polar stratospheric cloud particles. This set of models allows us to calculate a vast range of possible extinction spectra for aerosols. and from these, derive a set of eigenvectors which then provide the basis set used in our inversion algorithm. Our aerosol algorithm and retrievals are described in several articles (listed in References Section) published under this grant. In particular they allow us to analyze the spectral properties of aerosols and PSCs and ultimately derive their microphysical properties. We have found some considerable differences between our spectra and the ones derived from the SAGE III operational algorithm. These are interesting as they provide an independent check on the validity of published aerosol data and, in particular, on their associated uncertainties. In order to understand these differences, we are assembling independent aerosol data from other sources with which to make comparisons. We have carried out extensive comparisons of our ozone retrievals with both SAGE III and independent lidar, ozonesonde, and satellite measurements (Polyakov et al., 2004). These show very good agreement throughout the stratosphere and help to quantify differences which can be attributed to natural variation in ozone versus that produced by algorithmic differences. In the mid - upper stratosphere, agreement with independent data was generally within 5 - 20%. but in the lower stratosphere the differences were considerably larger. We believe that a large proportion of this discrepancy in the lower stratosphere is attributable to natural variation, and is also seen in comparisons between lidar and ozonesonde measurements. NO2 profiles obtained with our algorithm were compared to those obtained through the SAGE III operational algorithm and exhibited differences of 20 - 40%. Our retrieved profiles agree with the HALOE NO2 measurements significantly better than those of the operational retrieval. In other work (described below), we are extending our aerosol retrievals into the infrared regime and plan to perform retrievals from combined uv-visible-infrared spectra. This work will allow us to use the spectra to derive the size and composition of aerosols, and we plan to employ our algorithms in the analysis of PSC spectra. We are presently also developing a limb-scattering algorithm to retrieve aerosol data from limb measurements of solar scattered radiation.

Newchurch, Michael J.↗
NASA NTRS1986

Evidence of large-scale structures in the atmosphere of the active K-dwarf component of V471 Tauri

Contemporaneous IUE ultraviolet spectra and visible photoelectric data of the eclipsing binary V471 Tauri (K2V + DA) between 1979 and 1985 was analyzed. The combined data detail the three-dimensional structure of atmospheric loops and their associated starspots on the K dwarf. The distribution of starspot regions on the surface of the K star was inferred from the visible photometry. When spots are located near the limb of the K dwarf prior to and shortly after the total eclipse of the white dwarf, absorption lines such as C II, C III, c IV, and Si IV appear superimposed on the continuum of the white dwarf. These absorption lines are likely caused by cool coronal loops overlying the spots in the atmosphere of the K dwarf. The loops can extend nearly one stellar radius above the surface of the K2V star.

Guinan, E. F.↗
NASA NTRS1986

Laser induced fluorescence and phosphorescence of matrix isolated glyoxal - Evidence for exciplex formation in the A 1Au and a 3Au states

Laser-induced fluorescence and phosphorescence as well as infrared and visible absorption spectra of glyoxal in Ar, N2, and CO matrices are presented and analyzed. Glyoxal in its first excited electronic state is shown to form an exciplex with its nearest neighbors in all three matrices, and transitions normally forbidden dominate the emission spectra. The spectral characteristics of these complexes are similar to those of the Ar-glyoxal complex found in supersonic beam experiments. Due to the matrix cage effect, no vibrational predissociation is observed. The phosphorescence lifetime is determined and an upper limit is given for the fluorescence lifetime. This, in combination with the relative intensities of fluorescence and phosphorescence, can be used to place limits on the quantum yields of the various relaxation processes.

Van Ijzendoorn, L. J.↗
NASA NTRS1990

Space station contamination study: Assessment of contaminant spectral brightness

The results presented show that spectral emissions which arise as a result of vehicle-ambient atmospheric interactions are significant and can become competitive with the natural zodiacal background up to altitudes as high as 400 km for the Vacuun Ultraviolet (VUV) and Visible Infrared Spectra (VIS) for the worst case conditions used. The empirical database on the induced environment of space vehicles is very sparse, and these results are based on a number of assumptions and cannot be regarded as definitive at the present time. Since the technique for doing calculations of this kind was developed in its preliminary form for the purpose of this study, a list of greatly improved estimates are provided of the contamination irradiances. Tasks which are considered most important in order to achieve a higher confidence level for the preliminary conclusions drawn are provided.

Torr, D. G.↗
NASA NTRS1991

Remote sensing of regional pyroclastic deposits on the north central portion of the lunar nearside

High-resolution 3.0-cm radar data for the Rima Bode regional pyroclastic deposit and a number of UV-visible reflectance spectra for regional pyroclastic deposits on the north-central portion of the lunar nearside are analyzed and compared to existing data. The data obtained indicate that small craters in this deposit excavated loose unwelded pyroclastic particles, suggesting that welded layers or lenses do not exist at depths within the deposit's core area. The 70-cm radar data indicate that the Roma Bode deposit is thinner than the pyroclastic unit on the Aristarchus Plateau. The surfaces of all these regional pyroclastic deposits are dominated by ilmenite-rich black spheres, and contamination by low-Ti, nonpyroclastic debris appears to be minimal. The fine-grained block-free uncontaminated Rima Bode would be ideal for lunar mining operations and for rapidly covering lunar base modules with an adequate thickness of shielding material for protection from meteorite impact and space radiation.

Hawke, B. R.↗