Content area
Full Text
The location of the Opportunity landing site was determined to better than 10-m absolute accuracy from analyses of radio tracking data. We determined Rover locations during traverses with an error as small as several centimeters using engineering telemetry and overlapping images. Topographic profiles generated from rover data show that the plains are very smooth from meter- to centimeter-length scales, consistent with analyses of orbital observations. Solar cell output decreased because of the deposition of airborne dust on the panels. The lack of dust-covered surfaces on Meridiani Planum indicates that high velocity winds must remove this material on a continuing basis. The low mechanical strength of the evaporitic rocks as determined from grinding experiments, and the abundance of coarse-grained surface particles argue for differential erosion of Meridiani Planum.
The Mars Exploration Rover (MER) Mission required accurate tracking of the location of Opportunity to ensure efficient drives and to place measurements in proper geological context, e.g., associating a rock target with a particular terrain or geologic unit (1-3). The location of the lander in inertial coordinates was determined by fitting direct-to-Earth, two-way, X-band Doppler radio transmissions and two passes of two-way Ultra High Frequency (UHF) Doppier transmissions between Opportunity and the Mars Odyssey Orbiter. Based on analyses of these observations, the landed location is 1.9483°S (with an accuracy of ~10 m) and 354.47417°E (with an accuracy of ~10 cm), translated to International Astronomical Union (IAU) 2000 areocentric coordinates. The landed location was also tied to Mars Global Surveyor (MGS) Mars Orbital Camera and MER descent image data to within ~10-m accuracy, by triangulation to three craters observed in the far field [through breaks in the local Eagle crater rim (4)] in Pancam images. These triangulation results, mapped to the cartographic network-derived MGS Mars Orbital Laser (MOLA) data (5), imply that the lander is located at 1.9462°S, 354.4734°E in IAU 2000 areocentric coordinates.
Opportunity stopped on the plains for a software upload on sols 75 to 78 (6), and its location (1.94752°S, 354.47716°E) was determined by analysis of two passes of UHF two-way Doppler tracking. The location was also determined by image-based triangulation to common features, with resultant values of 1.9453°S, 354.4766°E. For both landing and software-upload locations, the Doppler-based location was displaced 135 m at an...