Probing IMF using nanodust measurements from inside Saturn's magnetosphere

We present a new concept of monitoring the interplanetary magnetic field (IMF) by using in situ measurements of nanodust stream particles in Saturn's magnetosphere. We show that the nanodust detection pattern obtained inside the magnetosphere resembles those observed in interplanetary space and is associated with the solar wind compression regions. Our dust dynamics model reproduces the observed nanodust dynamical properties as well as the detection pattern, suggesting that the ejected stream particles can reenter Saturn's magnetosphere at certain occasions due to the dynamical influence from the time‐varying IMF. This method provides information on the IMF direction and a rough estimation on the solar wind compression arrival time at Saturn. Such information can be useful for studies related to the solar wind‐magnetosphere interactions, especially when the solar wind parameters are not directly available. Key Points A new method to probe IMF with nanodust measurements inside the magnetosphere Under changing IMF, ejected nanoparticles can re‐enter Saturn‐s magnetosphere IMF direction and solar wind compression arrival time can be derivedPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/99078/1/grl50604.pd

In situ collection of dust grains falling from Saturn's rings into its atmosphere

Saturn's main rings are composed of >95% water ice, and the nature of the remaining few percent has remained unclear. The Cassini spacecraft's traversals between Saturn and its innermost D ring allowed its cosmic dust analyzer (CDA) to collect material released from the main rings and to characterize the ring material infall into Saturn. We report the direct in situ detection of material from Saturn's dense rings by the CDA impact mass spectrometer. Most detected grains are a few tens of nanometers in size and dynamically associated with the previously inferred "ring rain." Silicate and water-ice grains were identified, in proportions that vary with latitude. Silicate grains constitute up to 30% of infalling grains, a higher percentage than the bulk silicate content of the rings

Close Cassini flybys of Saturn's ring moons Pan, Daphnis, Atlas, Pandora, and Epimetheus

Saturn’s main ring system is associated with a set of small moons that are either embedded within it, or interact with the rings to alter their shape and composition. Five close flybys of the moons Pan, Daphnis, Atlas, Pandora, and Epimetheus were performed between December 2016 and April 2017 during the Ring-grazing Orbits of the Cassini mission. Data on the moons’ morphology, structure, particle environment, and composition were returned, along with images in the ultraviolet and thermal infrared. The optical properties of the moons’ surfaces are determined by two competing processes: contamination by a red material formed in Saturn’s main ring system, and by accretion of bright icy particles or water vapor from volcanic plumes originating on the planet’s moon Enceladus

2002 Kuiper prize lecture: Dust astronomy

Grun E, Srama R, Kruger H, et al. 2002 Kuiper prize lecture: Dust astronomy. Icarus. 2005;174(1):1-14.Dust particles, like photons, carry information from remote sites in space and time. From knowledge of the dust particles ' birthplace and their bulk properties, we can learn about the remote environment Out of which the particles were formed. This approach is called "Dust Astronomy" which is carried out by means of a dust telescope on a Dust Observatory in space. Targets for a dust telescope are the local interstellar medium and nearby star forming regions, as well as comets and asteroids. Dust from interstellar and interplanetary sources is distinguished by accurately sensing their trajectories. Trajectory sensors may use the electric charge signals that are induced when charged grains fly through the detector. Modern in-situ dust impact detectors are capable of providing mass, speed, physical and chemical information of dust grains in space. A Dust Observatory mission is feasible with state-of-the-art technology. It will (1) provide the distinction between interstellar dust and interplanetary dust of cometary and asteroidal origin, (2) determine the elemental composition of impacting dust particles, and (3) monitor the fluxes of various dust components as a function of direction and particle masses. (c) 2004 Elsevier Inc. All rights reserved

Cassini between Venus and Earth: Detection of interstellar dust

Altobelli N, Kempf S, Landgraf M, et al. Cassini between Venus and Earth: Detection of interstellar dust. Journal of Geophysical Research. 2003;108(A10):LIS 7-1-LIS 7-9.[1] We report the successful in situ measurement of interstellar dust particles inside the orbit of the Earth with the Cosmic Dust Analyzer (CDA) on the Cassini spacecraft. The impact ionization subsystem of the CDA is similar to the instruments on Ulysses and Galileo. As the heliocentric velocity and the direction of the interstellar dust flux are well known from Ulysses measurements, a combined analysis of the impact charge signals together with geometric and kinematic spacecraft data allowed us to separate interplanetary impacts from interstellar ones. The mean interstellar flux between 0.7 and 1.2 AU derived from our analysis is 2.5 +/- 0.5 . 10(-5) m(-2) s(-1), in a mass range of 5 . 10(-17) kg to 10(-15) kg which is in good agreement with the interstellar dust flux measured by Ulysses at 3 AU during the same time period [Landgraf et al., 2003]. The simultaneous detection of interstellar grains by Ulysses at 3 AU and approximately 1 AU by Cassini proves that big interstellar grains (radius greater than 0.4 mum), can penetrate deeply into the inner solar system