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Observed Changes in the Gravity Field of Mars Due to Seasonal Atmospheric ProcessesThe atmosphere of Mars deposits approximately 30% of its mass at the winter pole as part of its seasonal cycle of CO2 exchange and sublimes it back to the atmosphere in the spring, thus creating an annual hemispheric cycle of mass re-distribution. Using X-band tracking data of the Mars Global Surveyor (MGS) spacecraft, we have detected the signature of changes in the low degree gravity field from March 1999 through August 2000, corresponding to about three-quarters of a Martian year. The observed variations show a general resemblance to predicted variations from general circulation models. Also observed are irregular changes that appear to be due to transient phenomena in the Martian atmosphere such as large dust storms that provide significant heat into the lower atmosphere, even in the polar regions. In addition, we have identified a change in the rate of rotation of Mars over this same period that appears somewhat smaller than anticipated, but in general agreement with general circulation models.
Document ID
20010022249
Acquisition Source
Ames Research Center
Document Type
Preprint (Draft being sent to journal)
Authors
Smith, David E.
(NASA Ames Research Center Moffett Field, CA United States)
Zuber, M. T.
(NASA Ames Research Center Moffett Field, CA United States)
Dunn, P. J.
(NASA Ames Research Center Moffett Field, CA United States)
Torrence, M. H.
(NASA Ames Research Center Moffett Field, CA United States)
Fricke, S. K.
(NASA Ames Research Center Moffett Field, CA United States)
Date Acquired
August 20, 2013
Publication Date
January 1, 2000
Subject Category
Lunar And Planetary Science And Exploration
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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