Publications

The Cassini RADAR instrument is a multimode 13.8 GHz multiple-beam sensor that can operate as a synthetic-aperture radar (SAR) imager, altimeter, scatterometer, and radiometer. The principal objective of the RADAR is to map the surface of Titan. This will be done in the imaging, scatterometer, and radiometer modes. The RADAR altimeter data will provide information on relative elevations...

No abstract available.

The northern and southern seasonal polar caps of Mars are formed in the polar night, during their respective autumn and winter seasons, by the condensation of atmospheric CO2directly to the solid phase as ice, snow, and possibly frost. During spring and summer, the seasonal ice sublimes, returning CO2 to the atmosphere. The caps advance and recede in response to seasonal variations in...

The Microscopic Imager on the Spirit rover analyzed the textures of the soil and rocks at Gusev crater on Mars at a resolution of 100 micrometers. Weakly bound agglomerates of dust are present in the soil near the Columbia Memorial Station. Some of the brushed or abraded rock surfaces show igneous textures and evidence for alteration rinds, coatings, and veins consistent with secondary

The magnetic properties experiments are designed to help identify the magnetic minerals in the dust and rocks on Mars—and to determine whether liquid water was involved in the formation and alteration of these magnetic minerals. Almost all of the dust particles suspended in the martian atmosphere must contain ferrimagnetic minerals (such as maghemite or magnetite) in an amount of ∼2% by...

We describe USGS topomapping of Mars at resolutions from 100 m to 30 µm with data from the latest spacecraft missions. Analysis of NASA 2001 Mars Odyssey Thermal Emission Imaging System (THEMIS) data combining daytime visible reflected, daytime IR emitted, and nighttime IR emitted images allows us to isolate the physical effects of topography, albedo, and thermal inertia. To a good...

The U.S. Geological Survey has recently completed a final revised version of its 231 m/pixel global Viking image mosaic of Mars that has substantially improved geodetic accuracy compared to versions released in 1991 and 2001. This mosaic, known as MDIM 2.1, is currently available in the USGS ISIS file format (see http://astrogeology.usgs.gov/Projects/MDIM21/) and will be formatted and...

The U.S. Geological Survey has recently completed a final revised version of its 231 m/pixel global Viking image mosaic of Mars that has substantially improved geodetic accuracy compared to versions released in 1991 and 2001. This mosaic, known as MDIM 2.1, is currently available in the USGS ISIS file format and will be formatted and submitted to the NASA Planetary Data System (PDS) in...

We observed active pahoehoe lobes erupted on Kilauea during May-June 1996, and found a range of emplacement styles associated with variations in local effusion rate, flow velocity, and strain rate. These emplacement styles were documented and quantified for comparison with earlier laboratory experiments. At the lowest effusion rates, velocities, and strain rates, smooth-surfaced lobes...

No abstract available.

Mars is a very watery planet, but all the water seems to be frozen. Divining the amount and distribution of this water, past and present, is essential for understanding martian climates, and more.

We have begun work to prepare for producing controlled 2001 Mars Odyssey THEMIS infrared (IR) and visible (VIS) global mosaics of Mars. This effort is being coordinated with colleagues from Arizona State University and on the THEMIS team who plan to address radiometric issues in making such mosaics. We are concentrating on geometric issues. Several areas of investigation are now in...