Atmospheric entry profiles from the Mars Exploration Rovers Spirit and Opportunity

Accelerometer measurements made by Spirit and Opportunity during their entries through the martian atmosphere are reported. Vertical profiles of atmospheric density, pressure, and temperature with sub-km vertical resolution were obtained using these data between 10 and 100 km. Spiritʹs temperature profile is ∼ 10   K warmer than Opportunityʹs between 20 and 80 km. Unlike all other martian entry profiles, Spiritʹs temperature profile does not contain any large amplitude, long wavelength oscillations and is nearly isothermal below 30 km. Opportunityʹs temperature profile contains a strong inversion between 8 and 12 km. A moderate dust storm, which occurred on Mars shortly before these two atmospheric entries, may account for some of the differences between the two profiles. The poorly known angle of attack and unknown wind velocity may cause the temperature profiles to contain errors of tens of Kelvin at 10 km, but these errors would be an order of magnitude smaller above 30 km. On broad scales, the two profiles are consistent with Mars Global Surveyor Thermal Emission Spectrometer (TES) pressure/temperature profiles. Differences exist on smaller scales, particularly associated with the near-isothermal portion of Spiritʹs profile and the temperature inversion in Opportunityʹs profile.