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- Krüger, H., et al.
(författare)
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Four years of Ulysses dust data: 1996-1999
- 2001
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Ingår i: Planetary and Space Science. - 1873-5088. ; 49:13, s. 1303-1324
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Tidskriftsartikel (refereegranskat)abstract
- The Ulysses spacecraft is orbiting the Sun on a highly inclined ellipse(/i=79°, perihelion distance 1.3 AU, aphelion distance 5.4 AU).Between January /1996 and December /1999 the spacecraft was beyond 3 AUfrom the Sun and crossed the ecliptic plane at aphelion in May /1998. Inthis 4-yr period 218 dust impacts were recorded with the dust detectoron board. We publish and analyse the complete data set of both raw andreduced data for particles with masses10-16-10-8g. Together with 1477 dust impactsrecorded between launch of Ulysses and the end of /1995 publishedearlier (Grün et al., Planet. Space Sci. 43 (/1995a) 971;Krüger et al., Planet. Space Sci. 47 (/1999b) 363), a data set of1695 dust impacts detected with the Ulysses sensor between October /1990and December /1999 is now available. The impact rate measured between1996 and 1999 was relatively constant with about 0.2 impacts per day.The impact direction of the majority of the impacts is compatible withparticles of interstellar origin, the rest are most likelyinterplanetary particles. The observed impact rate is compared with amodel for the flux of interstellar dust particles. The flux of particlesseveral micrometres in size is compared with the measurements of thedust instruments on board Pioneer 10 and Pioneer 11 beyond 3 AU (Humes,J. Geophys. Res. 85 /(1980) 5841). Between 3 and 5 AU, Pioneer resultspredict that Ulysses should have seen 5 times more (~10mum sized)particles than actually detected.
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| 2. |
- Krüger, H., et al.
(författare)
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One year of Galileo dust data from the Jovian system: 1996
- 2001
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Ingår i: Planetary and Space Science. - 1873-5088. ; 49:13, s. 1285-1301
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Tidskriftsartikel (refereegranskat)abstract
- The dust detector system onboard Galileo has recoding dust impacts incircumjovian space since the spacecraft was injected into a bound orbitabout Jupiter in December 1995. This is the sixth in a series of papersdedicated to presenting Galileo and Ulysses dust data. We present datafrom the Galileo dust instrument for the period January to December 1996when the spacecraft completed four orbits about Jupiter (G1, G2, C3 andE4). Data were obtained as high-resolution realtime science data orrecorded data during a time period of 100 days, or via memory read-outsduring the remaining times. Because the data transmission rate of thespacecraft is very low, the complete data set (i.e. all parametersmeasured by the instrument during impact of a dust particle) for only 2%(5353) of all particles detected could be transmitted to Earth; theother particles were only counted. Together with the data for 2883particles detected during Galileo's interplanetary cruise and publishedearlier, complete data of 8236 particles detected by the Galileo dustinstrument from 1989 to 1996 are now available. The majority ofparticles detected are tiny grains (about 10nm in radius) originatingfrom Jupiter's innermost Galilean moon Io. These grains have beendetected throughout the Jovian system and the highest impact ratesexceeded 100min-1. A small number of grains has been detectedin the close vicinity of the Galilean moons Europa, Ganymede andCallisto which belong to impact-generated dust clouds formed by (mostlysubmicrometer sized) ejecta from the surfaces of the moons (Krügeret al., /1999e. Nature 399, 558). Impacts of submicrometer to micrometersized grains have been detected throughout the Jovian system andespecially in the region between the Galilean moons.
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