  Although the methods and techniques have been greatly improved since the late
nineteenth century, the precision on the measurement of the gravitational
constant G does not exceed 1 part in 1000. Intrinsic variations of G caused by
the geomagnetic field may explain the observed dispersion of the laboratory
measurements. This involves a coupling between gravitation and electromagnetism
(hereafter GE coupling) and a dependance of the effective G constant with
latitude and longitude. In this paper I analyse the effects of this coupling in
the framework of classical space mechanics by focusing on heliosynchronous
orbits. The predictions are found inconsistent with experimental data from the
SPOT mission.
