Engineering topics
Publications and source records attributed to Schroeder, R. D..
Using the Viking and Mars Pathfinder landing sites as a guide, this study assessed rock shapes, sizes and burial so they could be compared with rocks on the test platforms. This work allowed comparison of the severity of the rock distributions on the test platforms with the 3 landing sites and helped guide the rocks used on the test platforms during the final airbag qualification tests.
The Viking and Mars Pathfinder landing sites and a wide variety of rocky locations on the Earth show size-frequency distributions that follow an exponential when expressed in cumulative fractional area covered by rocks of a given diameter or larger versus diameter plots. Mars lander rock distributions have been fit by an equation of the form: Fk(D) = k exp [-q(k) D], where Fk(D) is the cumulative fractional area covered by rocks of diameter D or larger, k is the total area covered by all rocks, and an exponential q(k) = 1.79 + 0.152/k, which governs how abruptly the area covered by rocks decreases with increasing diameter. These distributions form a family of noncrossing curves that flatten out at small rock diameter at a total rock abundance of 5-40%. Model rock size-frequency distributions indicate a low probability of impacting hazardous rocks during MER landing. Rocks large enough to analyze and abrade by the rover should be plentiful within an easy Sol's drive.
As an aid in constraining the rock size-frequency distributions at the Mars Exploration Rover (MER) landing sites, Mars Orbiter Camera (MOC) images of all potential MER landing sites were systematically searched for boulder fields. Low-Sun angle MOC images can be used to identify boulders larger than 1.5 m diameter, which can be used to determine the shape of the rock size-frequency distributions. These distributions can be compared with the rock size-frequency distributions measured at the Viking and Mars Pathfinder landing sites to better quantify potentially hazardous rocks at the MER landing sites.