Rock size-frequency distributions on Mars and implications for Mars Exploration Rover landing safety and operations

• Published in: Journal of Geophysical Research - Planets Vol. 108; no. E12; pp. 8086 - n/a
• Main Authors: Golombek, M. P., Haldemann, A. F. C., Forsberg-Taylor, N. K., DiMaggio, E. N., Schroeder, R. D., Jakosky, B. M., Mellon, M. T., Matijevic, J. R.
• Format: Journal Article
• Language: English
• Published: American Geophysical Union 01-12-2003; Blackwell Publishing Ltd
• Subjects: Gusev; Mars; Mars Exploration Rover landing sites; Mars Pathfinder landing site; Meridiani; Physical properties of materials; Planetology; Remote sensing; rocks; Solar System Objects; Solid Surface Planets; Surface materials and properties; thermal inertia
• ISSN: 0148-0227; 2156-2202
• DOI: 10.1029/2002JE002035

The cumulative fractional area covered by rocks versus diameter measured at the Pathfinder site was predicted by a rock distribution model that follows simple exponential functions that approach the total measured rock abundance (19%), with a steep decrease in rocks with increasing diameter. The distribution of rocks >1.5 m diameter visible in rare boulder fields also follows this steep decrease with increasing diameter. The effective thermal inertia of rock populations calculated from a simple empirical model of the effective inertia of rocks versus diameter shows that most natural rock populations have cumulative effective thermal inertias of 1700–2100 J m−2 s−0.5 K−1 and are consistent with the model rock distributions applied to total rock abundance estimates. The Mars Exploration Rover (MER) airbags have been successfully tested against extreme rock distributions with a higher percentage of potentially hazardous triangular buried rocks than observed at the Pathfinder and Viking landing sites. The probability of the lander impacting a >1 m diameter rock in the first 2 bounces is <3% and <5% for the Meridiani and Gusev landing sites, respectively, and is <0.14% and <0.03% for rocks >1.5 m and >2 m diameter, respectively. Finally, the model rock size‐frequency distributions indicate that rocks >0.1 m and >0.3 m in diameter, large enough to place contact sensor instruments against and abrade, respectively, should be plentiful within a single sol's drive at the Meridiani and Gusev landing sites.