N. O. Snider

Mantled and exhumed terrains in Terra Meridiani, Mars

[1]xa0Hematite-bearing deposits in the Terra Meridiani region of Mars constitute the top stratum of a partially eroded layered complex that covers dissected Noachian-aged cratered terrain. The hematite unit consists of dark plains and dunes covering a bright substrate. This substrate is fully exposed beyond the borders of the hematite-bearing deposit and consists of polygonal ground separated by ridges or valleys, together with layered deposits that have been eroded into a variety of landforms. The complex is partially covered by a regional-scale aeolian mantle that thickens toward the north. The hematite-bearing stratum exhibits low albedoes, pulse widths, and intermediate thermal inertias, whereas the underlying unit exhibits high values of these parameters. Both units have spectral emissivity signatures similar to those for the low albedo cratered terrain to the south, with the addition of hematite for the top stratum. The complex is interpreted to consist of extensive plains-forming lava flows and tephra deposits emplaced during an extensional regime and at least partially buried by an aeolian mantle. Aeolian stripping of the mantle exposed much of the complex and differentially eroded the deposits to produce the landforms existent today. Exploration of the hematite-bearing deposits by the 2003 Mars Exploration Rover, “Opportunity,” will allow testing of the hypotheses presented since this stratum has been locally reworked into dunes that only partially cover the underlying brighter portion of the complex. In particular, the rover-based measurements will allow us to test the extent to which the unusual remote-sensing properties of the units indicate aqueous alteration.

FIDO prototype Mars rover field trials, Black Rock Summit, Nevada, as test of the ability of robotic mobility systems to conduct field science

[1]xa0The Field Integration Design and Operations (FIDO) prototype Mars rover was deployed and operated remotely for 2 weeks in May 2000 in the Black Rock Summit area of Nevada. The blind science operation trials were designed to evaluate the extent to which FIDO-class rovers can be used to conduct traverse science and collect samples. FIDO-based instruments included stereo cameras for navigation and imaging, an infrared point spectrometer, a color microscopic imager for characterization of rocks and soils, and a rock drill for core acquisition. Body-mounted “belly” cameras aided drill deployment, and front and rear hazard cameras enabled terrain hazard avoidance. Airborne Visible and Infrared Imaging Spectrometer (AVIRIS) data, a high spatial resolution IKONOS orbital image, and a suite of descent images were used to provide regional- and local-scale terrain and rock type information, from which hypotheses were developed for testing during operations. The rover visited three sites, traversed 30 m, and acquired 1.3 gigabytes of data. The relatively small traverse distance resulted from a geologically rich site in which materials identified on a regional scale from remote-sensing data could be identified on a local scale using rover-based data. Results demonstrate the synergy of mapping terrain from orbit and during descent using imaging and spectroscopy, followed by a rover mission to test inferences and to make discoveries that can be accomplished only with surface mobility systems.

Physical properties and localization investigations associated with the 2003 Mars Exploration rovers

[1]xa0A number of physical properties experiments will be conducted during the NASA 2003 Mars Exploration Rover Mission as the two vehicles explore Meridiani Planum and the floor of Gusev Crater. The investigations will include quantifying dust accumulation and dispersal dynamics by periodically monitoring the rover decks with the Athena Pancam and Mini-TES instruments. Properties of soil-like materials will be inferred from analyses of wheel track patterns, depths, and wheel slippage dynamics during traverses. The rovers will be modeled as dynamic mechanical systems to extract along-track terrain topography and physical properties from times series of rover tilt vectors, wheel encoder counts, azimuths, motor currents, and rocker and bogie angles. Trenches will be excavated using rover wheels to characterize mechanical properties of soil-like materials with depth and to expose subsurface materials for remote and in situ observations using the Athena Payload. The Rock Abrasion Tools will be used to expose rock subsurfaces for detailed analyses. Motor currents and penetration magnitudes will be compared to a database of rocks excavated by an engineering model of the Rock Abrasion Tool to understand Martian rock mechanical properties. Image-based localization analyses will be pursued to better understand rover traverse directions and magnitudes and thus rover locations as a function of time. The physical properties and localization investigations, when combined with analyses of the full ensemble of Athena observations, will greatly improve our understanding of Martian surface properties and provide significant technology lessons for future landed missions.

FIDO science payload simulating the Athena Payload

[1]xa0The Jet Propulsion Laboratorys Field Integrated Development and Operations rover (FIDO) emulates and tests operational rover capabilities for advanced Mars rover missions, such as those originally planned for the Mars Surveyor 2001 Rover and currently planned for the Athena Payload on the Mars Exploration Rovers scheduled for launch in 2003. This paper describes FIDOs science instrument payload, which is fully integrated with rover hardware and software. Remote science teams visualize instrument suite data and generate FIDO commands using the Web Interface for Telescience. FIDOs instrument suite has been used in terrestrial laboratory and field tests to simulate Mars operations, to train Mars scientists, and to improve Mars rover mission science operations protocols. The payload includes a deck-mounted, stowable mast that is deployed for acquisition of stereo imaging and spectral reflectance data. The mast head houses Pancam, Navcam (the navigation camera stereo pair), and the Infrared Point Spectrometer (IPS). Pancam is a three-band, false-color infrared (0.65, 0.74, 0.855 μm) stereo imaging system. The three wavelengths were chosen to yield information on the ferric nature of observed minerals. IPS acquires spectral radiance information over the wavelengths from 1.3 to 2.5 μm (spectral resolution ∼13 cm−1). A 4-degree-of-freedom arm is included on the front of FIDO. The arm end effector is the mounting point for a Color Microscopic Imager and an 57Fe Mossbauer Spectrometer. FIDO also carries a MiniCorer, which is an Athena prototype rock drill that can acquire 0.5-cm-diameter by up to 1.7-cm-long cores.