GALILEO PLASMA-WAVE OBSERVATIONS NEAR EUROPA

In this paper we present results from the Galileo plasma wave instrume nt during the first two flybys of Europa, which occurred on December 1 9, 1996, and February 20, 1997. Strong whistler-mode noise was observe d in the vicinity of Europa during both flybys. Emission at the upper hybrid resonance frequency, f(UH), and a propagation cutoff at the loc al electron plasma frequency, f(pe), provided measurements of the loca l electron number density. The electron density measurements show a re gion of highly disturbed plasma in the vicinity of Europa with density enhancements ranging from about 30 to 100 cm(-3) above the ambient Jo vian magnetospheric background, which in both cases was about 80 cm(-3 ).