Cassini Cosmic Dust Analyser: Composition of Dust at Saturn (original) (raw)

Preliminary Results on Analysis of the Cosmic Dust Analyzer Data Between Jupiter and Saturn

2007

We present the Cosmic Dust Analyzer (CDA) data obtained by the Cassini spacecraft during the interplanetary cruise phase between the Jupiter fly-by and the Saturn orbit insertion (SOI). Prior to the Cassini mission, the only in-situ dust detectors ever flown between Jupiter and Saturn were the Pioneer 10 and Pioneer 11 dust experiments. However, owing to the sensitivity of these instruments, only big particles (larger than 10 µm for Pioneer 10 and larger than 25 µm for Pioneer 11) could be detected. In contrast, CDA allows the detection of smaller grains. In particular, hundreds of high-velocity tiny dust particles, so-called stream particles, originating from both the Jovian and Saturnian systems were detected even at great distances from their source. In addition, we identified 17 interplanetary dust particles (IDPs), most probably of cometary origin, on moderate to high eccentric orbits. Furthermore, an impact cluster was identified, relying on both directional and temporal criteria, suggesting an encounter with a cometary trail. The shape of the impact charge signals suggests porous material for those particles.

Flux and composition of interstellar dust at Saturn from Cassini's Cosmic Dust Analyzer

Science (New York, N.Y.), 2016

Interstellar dust (ISD) is the condensed phase of the interstellar medium. In situ data from the Cosmic Dust Analyzer on board the Cassini spacecraft reveal that the Saturnian system is passed by ISD grains from our immediate interstellar neighborhood, the local interstellar cloud. We determine the mass distribution of 36 interstellar grains, their elemental composition, and a lower limit for the ISD flux at Saturn. Mass spectra and grain dynamics suggest the presence of magnesium-rich grains of silicate and oxide composition, partly with iron inclusions. Major rock-forming elements (magnesium, silicon, iron, and calcium) are present in cosmic abundances, with only small grain-to-grain variations, but sulfur and carbon are depleted. The ISD grains in the solar neighborhood appear to be homogenized, likely by repeated processing in the interstellar medium.

In situ dust measurements in the inner Saturnian system

Planetary and Space Science, 2006

In July 2004 the Cassini-Huygens mission reached the Saturnian system and started its orbital tour. A total of 75 orbits will be carried out during the primary mission until August 2008. In these four years Cassini crosses the ring plane 150 times and spends approx. 400 h within Titan's orbit. The Cosmic Dust Analyser (CDA) onboard Cassini characterises the dust environment with its extended E ring and embedded moons. Here, we focus on the CDA results of the first year and we present the Dust Analyser (DA) data within Titan's orbit. This paper does investigate High Rate Detector data and dust composition measurements. The authors focus on the analysis of impact rates, which were strongly variable primarily due to changes of the spacecraft pointing. An overview is given about the ring plane crossings and the DA counter measurements. The DA dust impact rates are compared with the DA boresight configuration around all

The COSMIC DUST ANALYZER for the CASSINI Mission to Saturn

International Astronomical Union Colloquium

In October 1997 a unique mission to the Saturnian system will be launched by NASA, the CASSINI mission. One goal of this mission is to study the Saturnian dust environment, and for this task, the COSMIC DUST ANALYZER (CDA) has been developed and is currently being tested. Impact ionization is used to determine the speed (1 - 100 km/s) and the mass (1•10–15 – 1•10–9 g) of impinging particles. Furthermore, the electric charge (1•10–15 – 1•10–12 C) of the particles can be measured via the induction principle, and an integrated time-of-flight mass spectrometer will analyze the chemical composition of individual dust particles. In order to achieve sufficient sensitivity for dust fluxes as low as 10 particles/(month-m2), the sensor has a large sensitive area of 0.1 m2. This paper will describe the function of the experiment.

Cassini dust stream particle measurements during the first three orbits at Saturn

Journal of Geophysical Research, 2011

Stream particles are nanometer-scale dust particles ejected with speeds^100 km s −1 from both the Jovian and Saturnian systems. Here we report the dynamical analysis of Saturnian stream particles on the basis of observations made by the Cosmic Dust Analyzer on board the Cassini spacecraft during its first three orbits around Saturn. The time span of the presented measurements covers from the beginning of orbit A to the end of orbit C (from the Saturn orbit insertion on 1 July 2004 UTC to 16 January 2005 UTC). During these orbits the Cassini spacecraft was usually located outside but not far from Saturn's magnetosphere. The Cassini observations therefore provide important information on the dynamics of stream particles just ejected from the system. As with earlier observations, two impact populations are identified. These appear as faint but continuous impacts as well as semiregular and energetic impact bursts. Faint impacts from directions close to the Saturn line of sight are recognized as recently ejected stream particles, while energetic dust bursts most probably consist of previously ejected particles that experienced significant acceleration within the solar wind. The presented measurements not only confirm the previous proposed stream particle ejection scenario but also serve as essential inputs for detailed dynamical modeling.

Cassini/Cosmic Dust Analyzer in situ dust measurements between Jupiter and Saturn

Journal of Geophysical Research, 2007

We report an analysis of the Cosmic Dust Analyzer data obtained during the interplanetary cruise of the Cassini spacecraft between Jupiter and Saturn. The data cover the time period between the Jupiter flyby and the Saturn orbit insertion. Seventeen dust particles on bound and unbound (hyperbolic) orbits were also detected, with sizes in the submicrometer to the micrometer range. Our measurements are compared with the Pioneer dust data obtained 30 years ago and model predictions. Particles on bound orbits have low eccentricities and low inclinations. Possible sources are short-period Jupiter family comets and circumsolar dust. The impactors on hyperbolic orbits were identified as being most likely interstellar dust (ISD) grains with a radius of %0.4 mm. The corresponding flux of %2 Â 10 À5 m À2 s À1 is in a very good agreement with the ISD flux measurements performed by the Ulysses spacecraft over the same time period.