Dust measurements during Galileo's approach to Jupiter and Io encounter

Science

Volumn 274, Issue 5286, 1996, Pages 399-401

  Grun E ^a   Hamilton, D P ^b   Riemann, R ^a   Dermott, S ^c   Fechtig, H ^a   Gustafson, B A ^c   Hanner, M S ^d   Heck, A ^a   Horanyi, M ^e   Kissel, J ^a   Kruger H ^a   Lindblad, B A ^f   Linkert, D ^a   Linkert, G ^a   Mann, I ^g   McDonnell, J A M ^h   Morfill, G E ⁱ   Polanskey, C ^d   Schwehm, G ^j   Srama, R ^a   Zook, H A ^k   more..

^a MAX PLANCK INSTITUT FÜR KERNPHYSIK   (Germany)

^b UNIVERSITY OF MARYLAND   (United States)

^c UNIVERSITY OF FLORIDA   (United States)

^d CALIFORNIA INSTITUTE OF TECHNOLOGY   (United States)

^e UNIVERSITY OF COLORADO   (United States)

^f LUND UNIVERSITY   (Sweden)

^g MAX PLANCK INSTITUT FÜR SONNENSYSTEMFORSCHUNG   (Germany)

^h UNIVERSITY OF KENT   (United Kingdom)

ⁱ MAX PLANCK INSTITUT FÜR EXTRATERRESTRISCHE PHYSIK   (Germany)

^j EUROPEAN SPACE AGENCY   (Netherlands)

^k NASA JOHNSON SPACE CENTER   (United States)

more..

Author keywords

[No Author keywords available]

Indexed keywords

ARTICLE; ASTRONOMY; ATMOSPHERE; CLOUD; DUST; IONIZATION; MAGNETIC FIELD; PARTICLE SIZE; PLASMA; PRIORITY JOURNAL; SPACE;

DUST; GALILEO;

IO; JUPITER;

EID: 0029659614     PISSN: 00368075     EISSN: None     Source Type: Journal    
DOI: 10.1126/science.274.5286.399     Document Type: Article

References (15)

1. 2 and a 140°-wide conical FOV. It was mounted on the spinning section of the Galileo spacecraft at an angle of 55° with respect to the positive spin axis (opposite to the antenna direction which pointed toward Earth). Only dust particles with relative velocity vectors within the FOV of the detector could be measured. The impact direction was determined by the spin position (or rotation angle) of the spacecraft at the time of impact. This sensor mounting direction constrained the directions from which dust grains could be sensed. This limitation varied with spacecraft rotation angle and with spacecraft location along its trajectory. During Galileo's approach to Jupiter dust particles impacting the DDS from the inner jovian system (that is, from inside the position of Galileo) could be detected when the detector was facing Jupiter; at a spin position half a rotation later DDS was facing away from Jupiter and these particles could not enter the detector. Shortly after Galileo's CA to Jupiter, Jupiter and the inner jovian system was in the Earth-facing hemisphere as seen from Galileo, and no dust grains emanating from that region could reach the dust detector.
2. E. Grün et al., Astron. Astrophys. Suppl. 92, 411 (1992).
3. E. Grün et al., Science 257, 1550 (1992).
4. Each event detected by DDS was recorded in two ways [see also E. Grün et al., Space Sci. 43, 941 (1995)]: (i) it was counted in 1 out of 24 accumulators according to its class and signal amplitude; and (ii) the complete information (all signal amplitudes, event time, sensor direction and other supplementary data) was stored in an instrument data frame (IDF). Up to 40 new IDFs were stored in DDS memory that were either continuously read out at high rate to the tape recorder or all 40 IDFs were read out at once in a memory-read-out (MRO). Each MRO contained a complete set of event counters. From these data impact rates were calculated. In addition to the counter information each MRO contained 16 IDFs of class 3 impacts and 24 IDFs of lower class events. The event time information that was included in an IDF had a time resolution of 4 hours. Depending on the impact rate and the time between two consecutive MROs the complete information of only a fraction of the impacts that were detected by DDS was received on Earth DDS data that were stored on Galileo's tape recorder contained highly time resolved information: a complete set of DDS data was recorded about once a minute.
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11. H. A. Zook et al., in Physics, Chemistry, and Dynamics of Interplanetary Dust, B. A. S. Gustafson and M. S. Hanner, Eds. [ASP Conference Series (1996)], vol. 104, pp. 23-25; H. A. Zook et al., Science, in press.
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15. We thank the project, operations, and data system teams from the Jet Propulsion Laboratory for their roles in the successful flight of Galileo to and around Jupiter and the recovery of high-quality data. This work was supported by DARA.