According to general relativity, the gravitomagnetic Lense-Thirring force of Mars would secularly shift the orbital plane of the Mars Global Surveyor (MGS) spacecraft by an amount of 1.5 m, on average, in the cross-track direction over 5 years. The determi

Table1:OrbitalparametersofMGSanditsLense-Thirringprecession.a˙LTisisthesemimajoraxis,iistheinclination,andeistheeccentricity. thegravitomagneticnodeprecessionand NLT istheaverageout-of-planegravitomagneticshiftover veyears.

33.8(masyr 1)3792.42(km)92.86(deg)0.00851.5(m)

ItcomesfromS=αMR2(2π/T),wherethepolarmomentisα=C/MR2=0.3654(Konoplivetal2006)andthesiderealrotationperiodisT=1.02595675d(Seidelmann1992).2Theformulasofeq.

(1)holdinaframewhosereferenceplaneisthecentralbody’sequator.ThisisjustthecasebecausetheMarsequatoristiltedonlyby1.7degtotheEarth’sequator,whichisthereferenceplaneoftheframeusedintheanalysisof(Konoplivetal.2006).Indeed,theobliquityofMarsandtheEarthamountto25.2degand23.5degrespectively.1

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