Empirical Estimates of Martian Surface Pressure in Support of the Landing of Mars Science Laboratory

Abstract

The aim of this work is to develop an empirical expression for diurnal mean martian surface pressure in support of the landing of Mars Science Laboratory. We eval- uate the consistency of surface pressure measurements from four landers, Viking Lander 1, Viking Lander 2, Mars Pathfinder, and Phoenix, and one radio occultation experiment, Mars Global Surveyor. With the exception of Mars Pathfinder, whose measurements are 0.1 mbar smaller than expected, all are consistent. We assume that the diurnal mean surface pres- sure is a separable function of altitude and season, neglecting dependences on time of day, latitude, and longitude, and use the Viking Lander 1 dataset to characterize the sea- sonal dependence as a harmonic function of season with annual and semi-annual periods. We characterize the exponential dependence of surface pressure on altitude using Mars Global Surveyor radio occultation measurements widely-distributed below +1 km altitude and within 45 degrees of the equator. These measurements have local times of 3-5 hours, which may introduce biases into our estimates for diurnal mean surface pressure. Our em- pirical expression for diurnal mean surface pressure, pdm ,i sp0,V L1 exp(−(z − z0,V L1)/H0)