I discuss some aspects of the recent test of frame-dragging performed by me by exploiting the Root-Mean-Square ( RMS ) orbit overlap differences of the out-of-plane component N of the orbit of the Mars Global Surveyor ( MGS ) spacecraft in the gravitational field of Mars .
A linear fit of the full time series of the entire MGS data ( 4 February 1999–14 January 2005 ) yields a normalized slope 1.03 \pm 0.41 ( with 95 \% confidence bounds ) .
Other linear fits to different data sets confirm the agreement with general relativity .
The huge systematic effects induced by the mismodeling in the martian gravitational field claimed by some authors are absent in the MGS out-of-plane record .
The non-gravitational forces affect at the same level of the gravitomagnetic one the in-plane orbital components of MGS , not the out-of-plane one .
Moreover , they experience high-frequency variations which does not matter in the present case in which secular effects are relevant .