THE FLUX OF INTERSTELLAR DUST OBSERVED BY ULYSSES AND GALILEO

Interstellar dust detected by the dust sensor onboard Ulysses was firs t identified after the Jupiter flyby when the spacecraft's trajectory changed dramatically (Grun et al., 1994). Here we report on two years of Ulysses post-Jupiter data covering the range of ecliptic latitudes from 0 degrees to -54 degrees and distances from 5.4 to 3.2 AU. We fin d that, over this time period, the flux of interstellar dust particles with a mean mass of 3.10(-13) g stays nearly constant at about 1.10-4 m(-2) s(-1) (pi sr)(-1) with both ecliptic latitude and heliocentric distance. Also presented are 20 months of measurements from the identi cal dust sensor onboard the Galileo spacecraft which moved along an in -ecliptic orbit from 1.0 to 4.2 AU. From the impact direction and spee ds of the measured dust particles we conclude that Galileo almost cert ainly sensed interstellar dust outside 2.8 AU; interstellar particles may also account for part of the flux seen between 1 and 2.8 AU.