Mars' Atmosphere: Comparison of Entry Profiles with Numerical Models
Murphy, James R.
Buzzard, Stephen S.
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As planetary probes enter an atmosphere, they capture measurements which provide thermodynamic information about the atmosphere, but only within a narrow vertical column within that atmosphere over a limited extent of time. In order to place this in situ information into context, it needs to be correlated with other less spatially resolved but more temporally extensive measurements, which can be provided by orbiters as well as numerical models. Before the entry probe is designed and developed, there needs to be some foreknowledge of conditions the probe will experience. Data from previous probes and orbiters can help, and models can aid by permitting investigation of conditions the orbiters may not have observed. Focusing on Mars, there are now six entry profiles available for analysis and interpretation, as well as a decade's worth of remotely sensed atmospheric thermal and aerosol characterization from orbiting platforms. Additionally, there are one-dimensional (vertical) and three-dimensional numerical models of the atmosphere available to provide predictions for entry probes [1,2,3] (and aerobraking spacecraft ) and to aid in interpretations of entry probe measurements. This presentation focuses upon the atmospheric variability that can be experienced by a probe, which has a dependency on atmospheric dust load, season, location (latitude and longitude), and "weather" (baroclinic waves, thermal tides, dust storms, etc.) The primary tool is a numerical model of the Martian atmosphere with significant heritage (NASA AMES GCM), with additional comparison to a new model in development with collaboration with the University of Michigan. Haberle, R. M., J.R. Barnes, J.R. Murphy, M. M Joshi, and J. Schaeffer, Meteorological Predictions for the Mars Pathfinder Lander. J. Geophys. Res., 102, 13301-13311, 1997. Tyler Jr., D., J.R. Barnes, E.D. Skyllingstad, Mesoscale and LES Model Studies of the Martian Atmosphere in Support of Phoenix, Submitted, J. Geophys. Res., Spring 2008. Michaels, T. I., and S.C.R. Rafkin, (2008), Meteorological Predictions for Candidate 2007 Phoenix Mars Lander Sites using MRAMS, Submitted, J. Geophys. Res., Spring 2008. Bougher, S.W., J.R. Murphy, J.M. Bell, R.W. Zurek, Prediction of the Structure of the Martian Upper Atmosphere for the Mars Reconnaissance Orbiter (MRO) Mission, Mars, 2, 10-20, 2006.