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G.M. Keating, R.H. Tolson, S.N. Noll, T.J. Schellenberg, R.L. Stephens, M.S. Bradford (George Washington Univ.), S.W. Bougher (Univ. of Arizona), J.L. Hollingsworth (NASA Ames)
An accelerometer experiment aboard the Mars Global Surveyor has provided insitu measurements of over 1600 vertical structures of the Mars thermosphere, compared to only 3 previously (Viking 1, Viking 2, Pathfinder). These measurements of vertical and latitudinal variations in density, temperature and pressure have been obtained in the afternoon in both the Northern and Southern Hemispheres between 110 and 170 km. The accelerometer experiment along with lower atmosphere measurements, has allowed us to establish the linkage between processes in the upper and lower atmosphere as well as linkage with topography. Unexpected results include: (1) enormous thermospheric responses in the Northern Hemisphere to regional dust storms in the Southern Hemisphere, (2) stationary (apparently topographically forced) planetary waves in the thermosphere which rotate with the planet creating factor of 2 variations with longitude, and (3) thermospheric densities persistently much higher than indicated in GCM's. The physical processes possibly responsible for these phenomena are discussed. Initial measurements from a similiar accelerometer aboard Mars Climate Orbiter arriving at Mars, September 1999, may also be shown.
This research was funded by the Jet Propulsion Laboratory and the National Aeronautics and Space Administration.