CONSIDERATION OF THE MARTIAN MAGNETOTAIL AS EVIDENCE FOR AN INTRINSICMAGNETIC-FIELD

It has been suggested by Verigin et al. [1993] that the response of th e Martian magnetotail to changes in the solar wind ram pressure indica tes the presence of an intrinsic dipole magnetic field. 3-D hybrid par ticle simulations of Mars were performed including the magnetotail reg ions. The simulations are in agreement with published Phobos 2 data fr om the 3 elliptical orbits and reproduce the magnetopause diameter dep endence on the solar wind ram pressure reported by Verigin et al. [199 3]. However, the simulations were performed with no intrinsic field pr esent, indicating that the dependence of the magnetotail width on ram pressure, is not a discriminator for the presence of the intrinsic fie ld.