2 YEARS OF ULYSSES DUST DATA

From October 18, 1990 to February 8, 1992 the Ulysses spacecraft traversed interplanetary space between the Earth and Jupiter; at Jupiter the spacecraft was deflected below the ecliptic onto a highly-inclined orbit (i similar to 80 degrees). Here, we report on dust impact data obtained from launch until the end of 1992, nearly a year after the Jupiter flyby. During that time (792 days), the Ulysses dust detector recorded 968 impacts of dust particles with masses ranging from 10(-16) g to 10(-8) g. The impact rate varied from as low as one impact per week during quiet times to more than one per minute during the dust stream of March 10-11, 1992. In this paper, we present and describe the complete data set including both raw and reduced data. The performance of the sensor, which has been very satisfactory so far, is discussed in detail together with the noise discrimination scheme employed. The instrument's detection threshold is given as a function of both the particle's mass and its speed relative to Ulysses. The derived impact rates and the distribution of particle masses, speeds and impact directions are compared to a model of the meteoroid complex.