Mars Pathfinder landing site: Evidence for a change in wind regime from lander and orbiter data

Surface features related to the wind are observed in the vicinity of the Ma rs Pathfinder (MPF) landing site data from the lander and in data from orbi t by the Viking Orbiter and Mars Global Surveyor missions. Features seen fr om the surface include wind tails associated with small rocks, barchanoid d uneforms, ripplelike patterns, and ventifact flutes cut into some rocks. Fe atures seen from orbit include wind tails associated with impact craters, r idges inferred to be duneforms, and modified crater rims interpreted to hav e been eroded and mantled by windblown material. The orientations of these features show two prevailing directions. One is inferred to represent winds from the northeast, which is consistent with strongest winds predicted by a general circulation model to occur during the Martian northern winter und er current conditions. A second wind blowing from the ESE was responsible f or modifying the crater rims and cutting some of the ventifacts. The two wi nd regimes could reflect a change in climate related to Mars' obliquity or some other, unknown factor. Regardless of the cause, the MPF area has been subjected to a complex pattern of winds and supply of small particles, and the original surface formed by sedimentary processes from Tiu and Ares Vall is flooding events has been modified by repeated burial and exhumation.