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Kieffer, H. H.

Publications and source records attributed to Kieffer, H. H..

At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2003

South Polar Cryptic Region Revisited: THEMIS Observations

The early part of the Mars Global Surveyor mission provided good TES coverage of the Mars south polar region. These data allow mapping of the polar cap recession, surface and atmospheric temperatures, and albedo features found within the seasonal cap itself over Ls = 180 - 270 deg. During this period, the seasonal south polar cap retreated continuously and asymmetrically around the geographic pole, similar to the observations of Viking in 1976- 1977 [3]. A prominent albedo feature on the seasonal cap is a region that appears almost as dark as bare ground, yet remains cold. We refer to this region, generally located between latitudes 85 deg. S and 75 deg. S and longitudes 150 deg. W and 310 deg. W, as the Cryptic region.

Titus, T. N.↗
NASA NTRS2001

Ephemeral Dark Spots Associated with Martian Gullies

Seasonal spots confined to the channels of the recently-discovered martian gullies are described and explanations offered for their origin. Additional information is contained in the original extended abstract.

Bridges, N. T.↗
NASA NTRS2000

TES Observations of the Martian Surface and Atmosphere

The Thermal Emission Spectrometer (TES) instrument is a Fourier transform Michelson interferometer operating with 10 or 5 cm(exp -1) sampling in the thermal infrared spectral region from 1700 to 200 cm(exp -1) (-6 to 50 micrometers) where virtually all minerals have characteristic fundamental vibrational absorption bands. The TES data used in this paper are among the 6 x 10(exp 7) spectra collected during the early mapping phase of the Mars Global Surveyor (MGS) mission from southern hemisphere winter to early summer (aerocentric longitude, L(sub s), 107 deg to 297 deg. The methodology for separating the surface and atmospheric components of the radiance from Mars, which allows detailed analysis and interpretation of surface mineralogy, is described in previous paper. Additional information is contained in original extended abstract.

Christensen, P. R.↗
NASA NTRS2000

Spring and Summer Changes at the South Pole as Seen by the Mars Orbiter Camera

The Mars Orbiter Camera (MOC) on the Mars Global Surveyor (MGS) spacecraft has been able to follow individual features as the CO2 frost disappears and exposes the material underneath. Because the orbit of MGS is inclined at an angle of 93 degrees relative to the equator, the spacecraft gets especially good coverage of the ring at 87 degrees latitude. The following is a list of phenomena that have been seen during the spring and summer at the South Pole: (1) Circular depressions that are approximately ten meters deep and hundreds of meters in diameter. They are found only within the residual polar cap, the part that survives the summer. The high areas between the depressions are flat-topped mesas whose sides are concave circular arcs. In some places the depressions form patterns that exhibit north-south symmetry, suggesting some control by sunlight; (2) Dark layers that are exposed on the walls of the mesas. Each layer is at most a few meters thick. The dark layers might accumulate during climatic episodes of high atmospheric dust content, or they might accumulate during the annual cycling of dusty CO2; (3) Albedo differences that develop during the summer within the residual cap. These include subtle darkening of the floors of the depressions relative to the mesas and occasional major darkening of the floors, especially near the edge of the cap. The floors and mesas form a distinct stratum, suggesting they represent a distinct compositional boundary. For instance the floors may be water and the mesas may be CO2; (4) Small dark features that appear in spring on the seasonal frost outside the residual cap. Some of the features have parallel tails that are clearly shaped by the wind. Others are more symmetric, like dark snowflakes, with multiple branching arms. After the CO2 frost has disappeared the arms are seen as troughs and the centers as topographic lows; (5) Polygons whose sides are dark troughs. Those that are outside the residual cap seem to disappear when the frost disappears. The polygons and the dark snowflakelike structures may be related, and suggest that CO2 frost may form cohesive slabs; (6) Irregular depressions outside the residual cap. They look like degraded versions of the circular depressions inside the residual cap, and may be a remnant of the cap's changing location; and (7) Areas of burial and exhumation of circular depressions. Thomas et al. give an example with a sharp boundary: On one side the depressions are buried and on the other side they are exposed. In other cases there are rounded troughs up to one kilometer wide, which are dark in summer and appear to have eroded down below the floor of the circular depressions.

Ingersoll, A. P.↗
NASA NTRS1999

Detection of Crystalline Hematite Mineralization on Mars by the Thermal Emission Spectrometer: Evidence for Near-surface Water

The Thermal Emission Spectrometer (TES) instrument on the Mars Global Surveyor (MGS) mission has discovered a remarkable accumulation of crystalline hematite ((alpha-Fe2O3) that covers an area with very sharp boundaries approximately 350 by 350-750 km in size centered near 2 S latitude between 0 and 5 W longitude (Sinus Meridiani). Crystalline hematite is uniquely identified by the presence of fundamental vibrational absorption features centered near 300, 450, and >525/cm, and by the absence of silicate fundamentals in the 1000/cm region. Spectral features resulting from atmospheric CO2, dust, and water ice were removed using a radiative transfer model. The spectral properties unique to Sinus Meridiani were emphasized by removing the average spectrum of the surrounding region. The depth and shape of the hematite fundamental bands show that the hematite is crystalline and relatively coarse grained (>5-10 micron). Diameters up to and greater than 100s of micrometers are permitted within the instrumental noise and natural variability of hematite spectra. Hematite particles <5-10 micron in diameter (either as an unpacked or hard-packed powders) fail to match the TES spectra. The spectrally-derived areal abundance of hematite varies with particle size from approximately 10% for particles >30 micron in diameter to 40-60% for unpacked 10 micron powders. The hematite in Sinus Meridiani is thus distinct from the fine-grained (diameter <5-10 micron), red, crystalline hematite considered, on the basis of visible, near-IR data, to be a minor spectral component in Martian bright regions like Olympus-Amazonis. Sinus Meridiani hematite is closely associated with a smooth, layered, friable surface that is interpreted to be sedimentary in origin. This material may be the uppermost surface in the region, indicating that it could be a late-stage sedimentary unit, or it could be a layered portion of the heavily cratered plains units. We consider five possible mechanisms for the formation of coarse-grained, crystalline hematite. These processes fall into two classes depending on whether they require a significant amount of near-surface water: (1) chemical precipitation that includes origin by (a) precipitation from oxygenated, Fe-rich water (iron formations), (b) hydrothermal extraction and crystal growth.

Christensen, P. R.↗
NASA NTRS1999

The Thermal Emission Imaging System (THEMIS) Instrument for the Mars 2001 Orbiter

The primary objective of the Thermal Emission Imaging System (THEMIS) on the Mars Surveyor '01 Orbiter is to study the composition of the Martian surface at high spatial resolution. THEMIS will map the surface mineralogy using multi-spectral thermal infrared images in 8 spectral bands from 6.5 to 14.5 microns. In addition, a band centered at 15 microns will be used to map atmospheric temperatures and provide an important aid in separating the surface and atmospheric components. The entire planet will be mapped at 100 m resolution within the available data volume using a multi-spectral, rather than hyperspectral, imaging approach. THEMIS will also acquire 20 m resolution visible images in up to 5 spectral bands using a replica of the Mars 98 Orbiter (MARCI) and Lander (MARDI) cameras. Over 15,000 panchromatic (3,000 5-color), 20 x 20 km images will be acquired for morphology studies and landing site selection. The thermal-infrared spectral region contains the fundamental vibrational absorption bands of most minerals which provide diagnostic information on mineral composition. All geologic materials, including carbonates, hydrothermal silica, sulfates, phosphates, hydroxides, silicates, and oxides have strong absorptions in the 6.5-14.5 micron region. Silica and carbonates, which are key diagnostic minerals in thermal spring deposits, are readily identified using thermal-IR spectra. In addition, the ability to identify all minerals allows the presence of aqueous minerals to be interpreted in the proper geologic context. An extensive suite of studies over the past 35 years has demonstrated the utility of vibrational spectroscopy for the quantitative determination of mineralogy and petrology. The fundamental vibrations within different anion groups, such as C03, S04, P04, and SiO4, produce unique, well separated spectral bands that allow carbonates, sulfates, phosphates, silicates, oxides, and hydroxides to be readily identified. Additional stretching and bending modes involving major cations, such as Mg, Fe, Ca, and Na, allow Further mineral identification, such as the excellent discriminability of minerals within the silicate and carbonate groups.

Christensen, P. R.↗
NASA NTRS1998

Results from the Mars Global Surveyor Thermal Emission Spectrometer

The Thermal Emission Spectrometer spectra of low albedo surface materials suggests that a four to one mixture of pyroxene to plagioclase, together with about a 35 percent dust component provides the best fit to the spectrum. Qualitative upper limits can be placed on the concentration of carbonates (<10 percent), olivine (<10 percent), clay minerals (<20 percent), and quartz (<5 percent) in the limited regions observed. Limb observations in the northern hemisphere reveal low-lying dust hazes and detached water-ice clouds at altitudes up to 55 kilometers. At an aerocentric longitude of 224 degrees a major dust storm developed in the Noachis Terra region. The south polar cap retreat was similar to that observed by Viking.

unmanned↗
NASA NTRS1993

(abstract) Galileo NIMS Thermal Observations of Asteroid 951 Gaspra

The Near Infrared Mapping Spectrometer (NIMS) onboard the Galileo spacecraft performed spectral and thermal imaging of asteroid 951 Gaspra during the spacecraft flyby on October 29, 1991. Measurements of the hemispherically averaged temperature on Gaspra as the spacecraft approached the asteroid will also be reported. Differences resulting from other choices for thermophysical parameters in the model will be explored. Similar measurements are currently being planned for the Galileo encounter with asteroid 243 Ida, which will occur in late August of 1993.

asteroid near infrared imaging Galileo Gaspra Ida↗
NASA NTRS1993

Preliminary report of lunar observations by the Near-Infrared Mapping Spectrometer (NIMS) during the second Galileo Earth-Moon encounter

The Galileo encounter with the Earth-Moon system on 8 Dec. 1992, provided a unique opportunity to observe the Moon. Galileo's closest approach to the Moon was at an altitude of about 110,000 km above an area at about latitude 60N, longitude 60E. During the 12 hours surrounding the time of lunar closest approach, 12 observational sequences were executed by the near-infrared mapping spectrometer (NIMS), many in coordination with other Galileo instruments. These NIMS observations provided nearly complete coverage of the illuminated crescent from phase angles of 123 deg to 14 deg. This phase-angle coverage with nearly constant illumination is not possible from Earth; it is expected to provide substantial new information on the nature of the lunar photometric function over wavelength. As of Jan. 1993, most of the analysis has focused on the highest resolution data (55 km/pixel).

Carlson, R. W.↗
NASA NTRS1987

The thermal properties of Martian surface materials at high lattitudes: Possible evidence for permafrost

Evidence is presented from analysis of Viking thermal mapping results that suggests a transition to high thermal inertial material at a depth of approx. 12 cm at +75 deg latitude. This was interpreted as reflecting the transition from ice poor soil to hard frozen permafrost. It was pointed out that such a transition would be expected on the basis of theoretical models of hard frozen permafrost distribution. Although permafrost is not the only plausible martian surface material with high thermal inertia, polar thermal mapping may turn out to be a powerful tool for determining the distribution of permafrost deposits and understanding their behavior. At this point, the circumstantial case for permafrost deposits in the north pole region of Mars is very strong.

Paige, D. A.↗
NASA NTRS1985

Geometric accuracy of Landsat-4 and Landsat-5 Thematic Mapper images

The geometric accuracy (GA) and errors in imagery by Landsat-4 and -5 were examined using data from regions with a minimal topography. A least-squares comparison was made between ground truth digitized photographs and TM data for prominent features displayed on a 1:24,000 map. The algorithms used for the transformation of the Landsat data to a Cartesian system are provided. Landsat-5 images had a calculated error of 11.2 m (0.4 pixel) and could not be improved with skew and affine-distortion corrections. However, the digitized images, including road tracks, were considered detailed enough for standard 1:50,000 maps. Landsat-5 imagery, when fully corrected, was consistently superior to Landsat-4 data.

Batson, R. M.↗
NASA NTRS1985

Comet Thermal Modeling

Past thermal models of cometary nuclei have tended to be restricted to hemispherical averages and have ignored many important effects such as surface heat flow, rotation period, or coma opacity. A computer based model called KRC/COM was developed which includes these and many other important effects to give a more accurate physical model of sublimation from icy cometary nuclei. Halley's Comet was used as a test case because of the high interest in the 1986 perihelion passage of that comet.

Weissman, P. R.↗
NASA NTRS1985

Intraband Radiometric Performance of the LANDSAT 4 Thematic Mapper

Those radiometric characteristics of the LANDSAT 4 thematic mapper (TM) that could be established without absolute calibration of spectral data were examined. Radiometrically raw (B type) data of three daytime and two nighttime scenes were used, including TM scenes from Washington, DC; northeast Arkansas; Cape Cod, MA; Roanoke, VA; Richmond, VA; and Silver Bell, AZ. The effective resolution in radiance is degraded by a factor of about 2 by the irregular width of the digital levels. Underpopulated levels are consistent over all bands and detectors, and are spaced an average of 4 digital numbers (DN) apart. In band 6, level 127 is avoided by a factor 30. Several detectors exhibit a change of gain with a period of several scans; the largest effect is about 4%. At high contrast boundaries, some of the detectors in band 5 commonly overshoot by several DN and require about 30 samples to recover. The high frequency noise level of each detector was characterized by the standard deviation of the first derivative in the sample direction across a flat field. A coherent-sinusoidal-noise pattern is evident in detector 1 of band 3. The correlation between the six reflective bands was determined and used to select three groups of bands whose aggregate first principal components contain the greatest total information. A composite of the first components of bands 1, 2, 3, bands 5 and 7, and band 4, together containing 89% of the information in the reflectance bands, has reduced the effect of noise.

Kieffer, H. H.↗
NASA NTRS1984

An improved thermal model for cometary nuclei

A thermal model for cometary nuclei is presented and used in comparisons of predictions with data on Halley's comet. The model considers the surface boundary conditions and heat diffusion equations, the sublimation rate of ice, the energy balance, and the dust production rate. Projections were made for the Halley nucleus over 18 latitudes from -85 to +85 deg, from 185 d before to 110 d after perihelion, and in 20 layers of its surface in 1.3 cm increments. Sublimation is predicted to increase by a factor of 2.2 every orbit, thereby allowing 320 returns for a nucleus with a coma, 710 returns with a bare ice nucleus. The gas production during the Giotto intercept at 0.9 AU will be 4.4 x 10 to the 29th molecules/sec, close to an estimate made during the 1910 return.

Weissman, P. R.↗
NASA NTRS1984

Intraband Radiometric Performance of the LANDSAT-4 Thematic Mapper

Radiometric characteristics of the LANDSAT 4 Thematic Mapper (TM) that can be established without absolute calibration of spectral data are examined. The analysis is based on radiometrically raw (B type) data of three daytime and two nighttime scenes. A set of 512 lines are examined on an individual detector basis. Subscenes selected for uniform-radiance are used to characterize subtle radiometric differences and noise problems. Virtually all nonideal performance is incorporated into the fully processed (P type) images, but disguised by the geometric resampling technique.

Kieffer, H. H.↗
NASA NTRS1984

Thermal modeling of Halley's Comet

The comet thermal model of Weissman and Kieffer is used to calculate gas production rates and other parameters for the 1986 perihelion passages of Halley's Comet. Gas production estimates are very close to revised pre-perihelion estimates by Newburn based on 1910 observations of Halley; the increase in observed gas production post-perihelion may be explained by a variety of factors. The energy contribution from multiply scattered sunlight and thermal emission by coma dust increases the total energy reaching the Halley nucleus at perihelion by a factor of 2.4. The high obliquity of the Halley nucleus found by Sekanina and Larson may help to explain the asymmetry in Halley's gas production rates around perihelion.

Weissman, P. R.↗