A SIMPLE TEST OF THE INDUCED NATURE OF THE MARTIAN TAIL

The cross tail component of the magnetic field in the Mars wake allows a simple test of the contribution of the intrinsic planetary magnetic field to the observed magnetic field. If the magnetic tail is entirel y induced, then the direction of this cross tail component should be h ighly correlated with the direction of the interplanetary magnetic fie ld that there can be little intrinsic contribution to the Martian magn etotail. This in turn implies that the upper limit to the Martian magn etic moment is about 4 x 10(11) Tm-3.