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NASA NTRS2017

Estimating Water Ice Abundance from Short-Wave Infrared Spectra of Drill Cuttings at Cryogenic Temperatures

NASA's Resource Prospector (RP) mission intends to visit a lunar polar region to characterize the volatile distribution. Part of the RP payload, the Near-infrared Volatile Spectrometer System (NIRVSS) is a spectrometer operating from 1600-3400 nm that provides sensitivity to water ice, and other volatiles. For multiple years, the NIRVSS system has been incorporated into on-going RP payload testing in a cryogenic vacuum facility at Glenn Research Center. Soil tubes of lunar simulants, prepared with known amounts of water, are placed in the vacuum chamber and cooled to cryogenic temperatures (soil temperatures of 110-170 K) and placed under low vacuum (a few x 10(exp -6) Torr). During these tests NIRVSS continuously measures spectra of soil cuttings emplaced onto the surface by a drill. Real time processing of NIRVSS spectra produces two spectral parameters associated with water ice absorption features near 2000 and 3000 nm that can be used to inform decision making activities such as delivery of the soil to a sealable container. Post-test collection and analyses of the soils permit characterization the water content as a function of depth. These water content profiles exhibit the characteristics of a vacuum desiccation zone to depths of about 40 cm. Subsequent to completion of the tests, NIRVSS spectra are processed to produce two spectral parameters associated with water ice absorption features near 2000 and 3000 nm. These features can be evaluated as a function of time, and correlated with drill depth, and other measurements, throughout the drilling activities. Until now no effort was attempted to quantitatively relate these parameters to water abundance. This is the focus of our efforts to be presented.

NASA's Resource Prospector (RP)↗
NASA NTRS1992

The Quickest, Lowest-cost Lunar Resource Assessment Program: Integrated High-tech Earth-based Astronomy

Science and technology applications for the Moon have not fully kept pace with technical advancements in sensor development and analytical information extraction capabilities. Appropriate unanswered questions for the Moon abound, but until recently there has been little motivation to link sophisticated technical capabilities with specific measurement and analysis projects. Over the last decade enormous technical progress has been made in the development of (1) CCD photometric array detectors; (2) visible to near-infrared imaging spectrometers; (3)infrared spectroscopy; (4) high-resolution dual-polarization radar imaging at 3.5, 12, and 70 cm; and equally important (5) data analysis and information extraction techniques using compact powerful computers. Parts of each of these have been tested separately, but there has been no programmatic effort to develop and optimize instruments to meet lunar science and resource assessment needs (e.g., specific wavelength range, resolution, etc.) nor to coordinate activities so that the symbiotic relation between different kinds of data can be fully realized. No single type of remotely acquired data completely characterizes the lunar environment, but there has been little opportunity for integration of diverse advanced sensor data for the Moon. Two examples of technology concepts for lunar measurements are given. Using VIS/near-IR spectroscopy, the mineral composition of surface material can be derived from visible and near-infrared radiation reflected from the surface. The surface and subsurface scattering properties of the Moon can be analyzed using radar backscattering imaging.

Pieters, Carle M.↗
NASA NTRS1980

Optics for future solar system exploration

The optics technology necessary for future solar system exploration is discussed. To satisfy the various mission objectives, optical components need to be of low weight, provide adequate spatial resolution and mapping coverage, provide necessary spectral resolution, provide means to perform adaptable mapping spectrometry, operate under low light levels, provide color images of high fidelity and operate under high temperatures. Future near-infrared mapping spectrometers are examined, and the use of focal-plane detectors to improve their sensitivity is discussed.

Norris, D. D.↗
NASA NTRS1981

Spectral mapping of Jupiter and the Galilean satellites in the near infrared

A near-infrared mapping spectrometer is included in the science complement of the Galileo Mission, which will explore Jupiter and its satellites in the mid-1980s. The objectives of the infrared mapping spectrometer experiment are to map compositional units on the surfaces of the Jovian satellites and to characterize the mineral content of these units. For Jupiter's atmosphere, this experiment will investigate such areas as cloud properties and the spatial and temporal variability of minor species. The instrument consists of a telescope, a plane grating spectrometer, a Si and InSb detector array, and a passive radiative cooler. The spectral range is 0.7-5.2 microns, covered with a resolution of 0.025 micron. A wobbling secondary mirror in the telescope provides one dimension of spatial scanning, while the other dimension is provided by motion of the spacecraft scan platform.

Carlson, R. W.↗
NASA NTRS1982

Integrating 128 element InSb array - Recent results

There has been a continuing evolution toward larger arrays of infrared detectors, and the technology base derived from the Galileo Near Infrared Mapping Spectrometer (NIMS) has been expanded to linear arrays including from 128 to 512 elements. This advance is based on the commercial availability of high-quality InSb photodiodes and 128/256 element FET switch MUX's (multiplexing elements). The present investigation is concerned with an experimental 128-element linear imager using InSb detectors and silicon MUX for readout. Attention is given to detector array electrical characteristics, the detector readout architecture, noise, and special effects.

Bailey, G.↗
NASA NTRS1985

Electrostatic shielding of a charged conducting sphere by a fine-mesh grounded screen

A simple model of an electrostatic-shielding arrangement that will reduce the electric field from the Near Infrared Mapper Spectrometer aboard the Galileo spacecraft is presented. The system considered consists of a charged conducting sphere held at a fixed absolute potential via a power source. This system is screened by a larger, concentric sphere made of fine mesh which is grounded. A derivation based on elementary principles of electrostatics is used to show that the shielding effectiveness of the screen can be expressed in terms of the separation between the two spheres and another quantity B that is an intrinsic property of the screen. For a given screen, B can be determined by measuring the capacitance per unit area and separation between a flat piece of the screen and a parallel metal plate.

Edmonds, L.↗
NASA NTRS1987

Sulfur-oxygen processes on Io

Laboratory studies of irradiated sulfur dioxide frost have found that sulfur trioxide should be formed as a consequence of the irradiation process. The spectral reflectance of solid sulfur trioxide was measured in the laboratory and it was found that the compound has strong absorption features at 3.37 and 3.70 microns. These features are not present in the spectral geometric albedo of Io. This is interpreted as an indication that sulfur trioxide may exist in such limited abundance that it is undetectable in disk averaged spectrophotometry. It is suggested that the Near-Infrared Mapping Spectrometer on the Galileo spacecraft should be able to identify condensed sulfur trioxide on Io particularly in regions bordering the sulfur dioxide deposits. The presence of elemental sulfur on Io's surface has been questioned on several grounds, most notably the suggested production process (quenched molten sulfur extrusions) and the effect of radiation (particularly X-rays) on some of the allotropes. Mixtures of sulfur allotropes were produced in the laboratory by quenching molten sulfur and it was found that the spectra indicate the presence of certain red-colored allotropes which are preserved upon quenching. The color of the sulfur glass produced is redder when the temperature of the original melt is higher. This is consistent with the suggestion that Io's spectral geometric albedo can be partly explained by the presence of quenched sulfur glasses.

Nelson, Robert M.↗
NASA NTRS1991

Galileo infrared imaging spectroscopy measurements at Venus

During the 1990 Galileo Venus flyby, the Near Infrared Mapping Spectrometer investigated the night-side atmosphere of Venus in the spectral range 0.7 to 5.2 micrometers. Multispectral images at high spatial resolution indicate substantial cloud opacity variations in the lower cloud levels, centered at 50 kilometers altitude. Zonal and meridional winds were derived for this level and are consistent with motion of the upper branch of a Hadley cell. Northern and southern hemisphere clouds appear to be markedly different. Spectral profiles were used to derive lower atmosphere abundances of water vapor and other species.

Carlson, R. W.↗
NASA NTRS1993

Galileo/NIMS near-infrared thermal imagery of the surface of Venus

Numerous highland and lowland features on the surface of Venus are observed in multispectral imagery acquired at approximately 50 km spatial resolution by the Near-Infrared Mapping Spectrometer (NIMS) on board the Galileo spacecraft in Feb. 1990. Specifically, such features are observed at 1.18 microns, a wavelength particularly sensitive to thermal emission from the hot, lower atmosphere (less than 10 km) and surface, and show up particularly well when this image is 'de-clouded' using a simultaneously-acquired 2.3-microns image of the upper, cloudy atmosphere. Due to the steep atmospheric temperature gradient (approximately 8 degrees per kilometer), hot lowland areas appear relatively bright, while cooler, highland areas appear dark (due to the steep atmospheric temperature gradient - approximately 8 degrees per kilometer - surface temperatures span approximately 100 K over the 13 kilometer range of surface altitudes observed in this image). Prominent highland features include Maxwell Montes (approximately 12 km altitude), Alpha Regio (2.5 km), Eistla Regio (approximately 2.0 km), Bell Regio (2-3 km), and the western edge of Aphrodite Terra (2-2.5 km). Low-lying regions include Sedna Planitia (-1.0 km), Tinatin Planitia (-0.5 km), and the Bereghinya Planitia (0 km). From correlations with radar altimetry maps, such imagery may place useful constraints on surface emissivity and temperature variations, as well as on the nature of continuum opacity of CO2 in the 1-micron region.

Carlson, R. W.↗
NASA NTRS1993

Latitudinal distribution of carbon monoxide in the deep atmosphere of Venus

A large number of i.r. spectra of Venus was obtained using the Near-Infrared Mapping Spectrometer (NIMS) on the Galileo spacecraft, during the February 1990 encounter. Preliminary results show an apparent increase in the tropospheric CO volume mixing ratio (vmr) in the northern polar region. Other possible explanations of the observations are examined and rejected and an increase of the CO abundance north of 47 deg N of (35 +/- 15)% is inferred. Some possible causes of this enhancement are suggested.

Collard, A. D.↗
NASA NTRS1993

Search for spatial variations of the H2O abundance in the lower atmosphere of Venus from NIMS-Galileo

The spectroscopic data of the Near-Infrared Mapping Spectrometer (NIMS), recorded during the Galileo flyby of Venus, are analysed to retrieve the water vapor abundance variations in the lower atmosphere of Venus at night. The 1.18 micrometer spectral window, which probes altitude levels below 20 km, is used for this purpose. Constraints on the CO2 continuum and far-wing opacity from existing ground-based high-resolution observations are included in the modelling of the NIMS spectra. The NIMS measurements can be fitted with a water vapor mixing ratio of 30 +/- 15 ppm, in agreement with analyses of ground-based nightside observations. The water vapor abundance shows no horizontal variations exceeding 20% over a wide latitude range (40 deg S, 50 deg N) on the nightside of Venus. Within the same selection of NIMS spectra, a large enhancement in the O2 fluorescence emission at 1.27 micrometer is observed at a latitude of 40 deg S, over a spatial area about 100 km wide.

Drossart, P.↗
NASA NTRS1993

The upper clouds of Venus: Determination of the scale height from NIMS-Galileo infrared data

The 3-5 micrometer thermal emission of the nightside of Venus, recorded by the Near-Infrared Mapping Spectrometer (NIMS) instrument at the time of the Galileo flyby of Venus, is analysed to infer the properties of the upper cloud boundary. From the global maps of Venus at fixed wavelengths, the limb darkening of the flux is measured at several latitudes, within each infrared channel. By using the nominal Pioneer Venus thermal profile, these data give access to two parameters: the cloud deck temperature and the cloud scale height. It is verified independently, from the NIMS spectra, that this thermal profile is consistent with all the NIMS observations, and that the thermal structure does not vary significantly in the latitude range (25 deg S, 30 deg N). Within this range, the cloud scale height is found to be constant with latitude, and is H = 5.2 km, with an accuracy of about 15%, taking into account the various sources of theoretical and observational uncertainties. At higher latitudes, the temperature profile becomes more isothermal and the presented method to retrieve H is no longer valid.

Roos, M.↗
NASA NTRS1995

The thermal structure and dynamics of the atmosphere of Venus between 70 and 90 km from the Galileo-NIMS spectra

An analysis of thermal profiles and dynamics over a wide range of latitudes for the venusian atmosphere between 70 and 90 km is presented based on high spatial resolution infrared spectra of the night side obtained by the near infrared mapping spectrometer (NIMS) experiment during the Galileo-Venus encounter in February 1990. Using the 4.3-micrometer CO2 absorption band, the temperature profile is retrieved in the 75- to 91-km altitude region over a latitudinal range of -59 deg to +64 deg. Compared to earlier observations from the Pioneer Venus mission, the temperature at 91 km is about 10 K higher and between 74 and 83 km about 3.6 K colder. An equator to pole warming at constant pressure levels is found and implications for the zonal wind profiles are drawn under the assumption that the atmosphere is in cyclostrophic balance in the region of 70 to 90 km. The results are in correspondence with direct wind measurements from ground-based observations at 95 km and 105 km altitude.

Roos-Serote, M.↗
NASA NTRS1995

Combined theory of reflectance and emittance spectroscopy

The theory in which either or both reflected sunlight and thermally emitted radiation contribute to the power received by a detector viewing a particulate medium, such as a powder in the laboratory or a planetary regolith, is considered theoretically. This theory is of considerable interest for the interpretation of data from field or spacecraft instruments that are sensitive to the near-infrared region of the spectrum, such as NIMS (near-infrared mapping spectrometer) and VIMS (visual and infrared mapping spectrometer), as well as thermal infrared detectors.

Hapke, Bruce↗
NASA NTRS1996

Near-Infrared Spectroscopy and Spectral Mapping of Jupiter and the Galilean Satellites: Results from Galileo's Initial Orbit

The Near Infrared Mapping Spectrometer performed spectral studies of Jupiter and the Galilean satellites during the June 1996 perijove pass of the Galileo spacecraft. Spectra fora5-micrometer hotspot on Jupiter are consistent with the absence of a significant watercloud above 8 bars and with a depletion of water compared to that predicted for solar composition, corroborating results from the Galileo probe. Great Red Spot (GRS) spectral images show that parts of this feature extend upward to 240 millibars, although considerable altitude-dependent structure is found within it. A ring of dense clouds surrounds the GRS and is lower than it by 3 to 7 kilometers. Spectra of Callisto and Ganymede reveal a feature at 4.25 micrometers, attributed to the presence of hydrated minerals or possibly carbon dioxide on their surfaces. Spectra of Europa's high latitudes imply that fine-grained water frost overlies larger grains. Several active volcanic regions were found on lo, with temperatures of 420 to 620 kelvin and projected areas of 5 to 70 square kilometers.

Carlson, R.↗
NASA NTRS2000

NASA Participation in the ISAS MUSES C Asteroid Sample Return Mission

NASA and Japan's Institute of Space and Astronautical Science (ISAS) have agreed to cooperate on the first mission to collect samples from the surface of an asteroid and return them to Earth for in-depth study. The MUSES-C mission will be launched on a Japanese MV launch vehicle in January 2002 from Kagoshima Space Center, Japan, toward a touchdown on the asteroid Nereus in September 2003. A NASA-provided miniature rover will conduct in-situ measurements on the surface. The asteroid samples will be returned to Earth by MUSES-C via a parachute-borne recovery capsule in January 2006. NASA and ISAS will cooperate on several aspects of the mission, including mission support and scientific analysis. In addition to providing the rover, NASA will arrange for the testing of the MUSES-C re-entry heat shield at NASA/Ames Research Center, provide supplemental Deep Space Network tracking of the spacecraft, assist in navigating the spacecraft and provide arrangements for the recovery of the sample capsule at a landing site in the U. S. Scientific coinvestigators from the U.S. and Japan will share data from the instruments on the rover and the spacecraft. They will also collaborate on the investigations of the returned samples. With a mass of about I kg, the rover experiment will be a direct descendant of the technology used to build the Sojourner rover. The rover will carry three science instruments: a visible imaging camera, a near-infrared point spectrometer and an alpha X ray spectrometer. The solarpowered rover will move around the surface of Nereus collecting imagery data which are complimentary to the spacecraft investigation. The imaging system will be capable of making surface texture, composition, and morphology measurements at resolutions better than 1 cm. The rover will transmit this data to the spacecraft for relay back to Earth. Due to the microgravity environment on Nereus, the rover has been designed to right itself in case it flips over. Solar panels on all sides of the rover will ensure that enough power will always be available to the rover to activate the motors needed to turn over. Posable struts will allow the rover to position its chassis such that the camera can be pointed straight down at the surface or straight up at the sky. The presentation will describe the mission, scientific objectives and current state of the rover in detail.

Jones, Ross↗