Reconstruction of Atmospheric Properties from Mars Science Laboratory Entry, Descent, and Landing

The successful Mars Science Laboratory entry, descent, and landing returned a wealth of in situ data that, when combined with orbiter remote sensing data and numerical modeling results, can be used to determine the state of the atmosphere. The entry atmosphere reconstruction included data from several sources: 1) temperature and pressure data from the Mars Reconnaissance Orbiter and Mars Climate Sounder instrument, 2) density derived from the Mars entry, descent, and landing instrument suite, 3) density derived from the vehicle's inertial measurement unit and knowledge of the vehicle aerodynamics, and 4) numerical mesoscale model results. No single data set is sufficient to understand the atmospheric state along the path flown by the spacecraft. Rather, the reconstructed profile of density is pieced together from the available data, along with some assumptions and inferences. The strategy used to combine the various data sets required a clear understanding of each source's strengths and weaknesses. The various data sets appear consistent and reinforce each other. From these data sets, a novel approach to anchoring reconstructed pressure data in the upper altitudes to observed data near the Gale Crater landing site is presented. The paper also describes how the anchoring technique, along with using postflight adjustments to mesoscale model data and in situ measurements are used to reconstruct the atmospheric state along the trajectory. The final reconstructed profile is compared with preflight predictions and implications of the new approach and lessons learned are also discussed.