Mars' time-variable gravity and its determination: Simulated geodesy experiments
Article first published online: 1 JUN 2005
Copyright 2005 by the American Geophysical Union.
Journal of Geophysical Research: Planets (1991–2012)
Volume 110, Issue E6, June 2005
How to Cite
2005), Mars' time-variable gravity and its determination: Simulated geodesy experiments, J. Geophys. Res., 110, E06001, doi:10.1029/2004JE002378., , , , , and (
- Issue published online: 1 JUN 2005
- Article first published online: 1 JUN 2005
- Manuscript Accepted: 23 MAR 2005
- Manuscript Revised: 21 JAN 2005
- Manuscript Received: 5 NOV 2004
 The seasonal carbon dioxide (CO2) cycle on Mars results in a time-variable global redistribution of mass. These large-scale variations are associated with changes in the gravity field, mainly in the two zonal gravity coefficients and , which have been recently evaluated from Doppler tracking data of the Mars Global Surveyor (MGS) spacecraft. In the present study, we calculated these variations from the mass redistribution obtained from outputs of two general circulation models (GCM) as well as from CO2 thickness measurements by the High Energy Neutron Detector (HEND) instrument on board the Mars Odyssey spacecraft and compared them to the observations. Tracking observations provide one of the most direct measures of the global-scale atmospheric mass cycle. However, the associated uncertainties are relatively large, partly because the low-degree zonals obtained from a single orbiter tracking analysis are contaminated by higher-degree harmonics which are shown to have nonnegligible seasonal variations. Thus we investigated possibilities to improve the determination of the time-variable gravity field by means of simulated geodesy experiments. Additional radio tracking of a second spacecraft with suitable orbital characteristics was shown to be able to separate the higher-degree geodetic signatures. Radio links between landers on the Martian surface and a near-polar orbiter can further better estimate especially the even zonals.