EUROPAS MAGNETIC SIGNATURE - REPORT FROM GALILEOS-PASS ON 19-DECEMBER-1996

On 19 December 1996 as Galileo passed close to Jupiter's moon, Europa, the magnetometer measured substantial departures from the slowly Vary ing background field of Jupiter's magnetosphere. Currents coupling Eur opa to Jupiter's magnetospheric plasma could produce perturbations of the observed size. However, the trend of the field perturbations is he re modeled as the signature of a Europa-centered dipole moment whose m aximum surface magnitude is similar to 240 nanotesla, giving a rough u pper limit to the internal field. The dipole orientation is oblique to Europa's spin axis. This orientation may not be probable for a field generated by a core dynamo, but higher order multipoles may be importa nt as they are at Uranus and Neptune. Although the data can be modeled as contributions of an internal field of Europa, they do not confirm its existence. The dipole orientation is also oblique to the imposed f ield of Jupiter and thus not directly produced as a response to that f ield. Close to Europa, plasma currents appear to produce perturbations with scale sizes that are smalt compared with a Europa radius.