3 YEARS OF GALILEO DUST DATA

From its launch in October 1989 until the end of 1992, the Galileo spa cecraft traversed interplanetary space from Venus to the asteroid belt and successfully executed close flybys of Venus, the Earth, and the a steroid Gaspra. The dust instrument has been operating most of the tim e since it was switched on in December 1989. Except for short time int ervals near Earth, data from the instrument were received via occasion al(once per week to once per month) memory read outs containing 282-81 8 bytes of data. All events (impacts or noise events) were classified by an onboard program into 24 categories. Over the three-year time spa n, the dust detector recorded 469 ''big'' dust impacts. These were cou nted in 21 of the 24 event categories. The three remaining categories of very low amplitude events contain mostly noise events. The impact r ate varied from 0.2 to 2 impacts per day depending on heliocentric dis tance and direction of spacecraft motion with respect to the interplan etary dust cloud. Because the average data transmission rate was very low, some data were not received on the ground. Complete data sets for 358 ''big'' impacts were received, but the other 111 ''big'' impacts were only counted. The observed impact rates are compared with a model of the meteoroid complex.