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Martin, T. Z.

Publications and source records attributed to Martin, T. Z..

At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2003

Near-surface temperatures at proposed Mars Exploration Rover land sites

Minimum nighttime temperature at the Mars Exploration Rover (MER) landing sites may limit power available for science activities and thus mission lifetime. Here, 1 m air temperature at the end of the nominal 90 sol primary mission are derived for the four primary and three previously considered MER landing sites based on Mars Global Surveyor Thermal Emmision Spectrometer thermal inertia and albedo, estimated opacity, and predictions of air temperature from a one-dimensional atmospheric model.

Mars atmosphere Mars Exploration Rover (MER) surfa↗
NASA NTRS2003

Galileo PPR at Io: High Resolution Scans Taken in Conjunction with SSA and NIMS Data

The Galileo Photopolarimeter-Radiometer (PPR), when used in the radiometry mode which is most often used at Io, is a long-wavelength infrared single-aperture photometer. It is sensitive to temperatures from about 60 to several hundred K, and is thus useful for studying the volcanoes and background temperatures on Io. PPR can take raster scan images when it is the primary instrument being used (these data were discussed last year, see Rathbun et al., 2002). It can also take data in ride-along mode in conjunction with another remote sensing instrument (either SSI or NIMS) producing one-dimensional temperature scans. The best data of this type were taken during the close approach flybys during orbits I24, I25, I27, I31, I32, and I33 and include measurements of the volcanoes Pele, Prometheus, Pillan, Zamama, Tvashtar, Daedalus, Amarani, Gish Bar, Isum, Emakong, Tupan, and Tohil.

Rathbun, J. A.↗
NASA NTRS2002

Recent Results from Galileo PPR at Io: Orbits I31 and I32

Recent Galileo PPR (Photo-Polarimeter Radiometer) results will be shown, including global day and nighttime maps, high latitude regional maps, and high-resolution scans across hotspots and from pole to pole. SO2 vapor pressure, global heatflow, and hotspot power outputs are estimated. Additional information is contained in the original extended abstract.

Rathbun, J. A.↗
NASA NTRS1999

Atmospheric Results from the MGS Horizon Science Experiment

The Horizon Science Experiment (HORSE) utilizes the Mars Horizon Sensor Assembly (MHSA) on the Mars Global Surveyor (MGS) orbiter to measure 15-micron band thermal emission from the Martian atmosphere. During the first two phases of aerobraking, from September 1997 to May 1998, and from September 1998 to March 1999, one of the four MGS quadrants was pointed well onto the planet consistently during the near-periapsis aerobraking passes, allowing the device to obtain data on the latitudinal variation of middle atmospheric temperature (0.2 - 2.0 mbar). Of particular interest during the first phase (L(sub s) = 182 - 300 deg) were the effects of a prominent dust storm at L(sub s) =224 deg, and wavelike behavior in the strong temperature gradient near the north polar cap. Additional information is contained in the original extended abstract.

Martin, T. Z.↗
NASA NTRS1994

(abstract) Galileo PPR Observations of Shoemaker-Levy 9

The Galileo spacecraft Photopolarimeter Radiometer (PPR), a hybrid visual/thermal IR instrument designed primarily to measure properties of the Jovian atmosphere, was employed for SL9 as a staring high-speed photometer at 945 and 678 nm, taking advantage of Galileo's direct view of the impact point.The PPR was able to acquire data at times when no other Galileo optical instruments could operate.

Galileo Jupiter Shoemaker-Levy 9 IR observations p↗
NASA NTRS1994

Wavelength calibration techniques and subtle surface and atmospheric absorption features in the Mariner 6, 7 IRS reflectance data

1994 marks the 25th anniversary of the Mariner 6 and 7 flyby missions to Mars. Despite its age, the Mariner 6,7 Infrared Spectrometer (IRS) data are a unique set of measurements that can provide important information about the Martian surface, atmospheric, and atmospheric aerosol composition. For certain mid-IR wavelengths, the IRS spectra are the only such spacecraft data obtained for Mars. At other wavelengths, IRS measured surface regions different from those measured by Mariner 9 or Phobos 2 and under different dust opacity conditions. We are interested in examining the IRS reflectance data in the 1.8 to 3.0 micron region because there are numerous diagnostic absorption features at these wavelengths that could be indicative of hydrated silicate minerals or of carbonate- or sulfate-bearing minerals. Groundbased telescopic data and recent Phobos ISM measurements have provided controversial and somewhat contradictory evidence for the existence of mineralogic absorption features at these wavelengths. Our goal is to determine whether any such features can be seen in the IRS data and to use their presence or absence to re-assess the quality and interpretations of previous telescopic and spacecraft measurements.

Bell, James F., III↗
NASA NTRS1993

Temporal and spatial mapping of atmospheric dust opacity and surface albedo on Mars

The Mariner 9 and Viking missions provided abundant evidence that eolian processes are active over much of the surface of Mars. Past studies have demonstrated that variations in regional albedo and wind streak patterns are indicative of sediment transport through a region, while thermal inertia data (derived from the Viking Infrared Thermal Mapper (IRTM) datasets) are indicative of the degree of surface mantling by dust deposits. We are making use of the method developed by T. Z. Martin to determine dust opacity from IRTM thermal observations. We have developed a radiative transfer model that allows corrections for the effects of atmospheric dust loading on observations of surface albedo to be made. This approach to determining 'dust-corrected surface albedo' incorporates the atmospheric dust opacity, the single-scattering albedo and particle phase function of atmospheric dust, the bidirectional reflectance of the surface, and accounts for variable lighting and viewing geometry.

Lee, S. W.↗
NASA NTRS1993

Studies of atmospheric dust from Viking IR thermal mapper data

Following earlier work to map the dust opacity of the Mars atmosphere, a number of separate studies have been performed employing the radiometric measurements of the Viking IR Thermal Mappers. These efforts have resulted in a new perspective on the atmospheric dust distribution during the Viking Mission, as well as quantitative measures useful in the modeling of likely behavior at other times, and improved boundary conditions for circulation models of Mars. The significant findings from these studies are presented.

Martin, T. Z.↗
NASA NTRS1993

Mass of Dust in the Martian Atmosphere

Estimates of the mass of dust suspended in the Martian atmosphere are derived from global and regional 9 opacity maps produced from Viking Infrared Thermal Mapper data.

Martian atmospere Viking Infrared Thermal Mapper d↗
NASA NTRS1992

New dust opacity maps from Viking IR thermal mapper data

Mapping of dust opacity of the Martian atmosphere, using the silicate-induced absorption of 9 micron radiation, was performed with the Viking Infrared Thermal Mapper (IRTM) data for several local dust storms and in a global sense. We present here the first results from an effort to extend the earlier mapping work to the period of the 1977b major storm, and to concentrate attention on the details of opacity behavior during the initial phases of the 1977a and b storms.

Martin, T. Z.↗
NASA NTRS1992

The Martian dust cycle

Martian dust plays a key role in determining the current climate of Mars, and is suspected of having had a major influence on the evolution of the surface and the history of climatic conditions on the planet. From spacecraft and ground-based observations, some understanding has been acquired of the styles and frequency of dust motion in the atmosphere and at the surface, of atmospheric dust loading, dust particle properties, and their variability. Limited constraints have also been derived for the volumes and ages of some potential dust reservoirs on the surface. These data are adequate to frame questions about the seasonal and long-term cycles of dust of Mars. Additional data are needed to place quantitative constraints on components of these cycles, on their possible linkage to one another, and to draw conclusions from the dust budget about the climate history of Mars.

Kahn, R. A.↗