Planetary Rings

It is very well known fact that dust and dusty plasmas are ubiquitous in the space: from interstellar media, to cometary dust, planetary rings and so on. The phenomena concerning the dust in space, seems to have an immense number of facets. The help for the identification of some of the phenomena, or tracing the new ones, has coming during

Odyssey 2 will be proposed in December 2010 for the next call of M3 missions for Cosmic Vision 2015-2025. This mission, under a Phase 0 study performed by CNES, will aim at Neptune and Triton. Two sets of objectives will be pursued. The first one is to perform a set of gravitation experiments at the Solar System scale. Experimental tests

EVIDENCE from the laboratory of Saturn's Rings solves riddles of planet formation. Observations by Cassini and other spacecraft show conditions similiar to the birth of our Solar System. These observations lead to new theories of small-body accretion. Applications have benefits for physics and energy on Earth. There have been several open questions regarding the planets. Most puzzling is the formation of mountain-sized planetesimals from protostellar dust, for these objects could not form naturally. Power source of the "dynamo" generating planetary magnetic fields was also unknown. Internal heat generated by planets and even small moons is an additional mystery. These riddles may be explained by presence of primordial singularities in the Solar System's formation. Saturn's Rings are a field of ice in which the tracks of these objects may be seen. The Cassini spacecraft has returned many fascinating images of the Rings. We now know them to be home to massive unseen objects. Satellite objects glimpsed in the Encke and Keeler gaps show behaviour unlike moons of rock or ice. Discrete trails of dirt and molecular oxygen indicate radiation discharge emanating from these objects. Similiar trails photographed in Cassini's Division indicate massive objects where no large object has been sighted visually. We must consider whether the Rings could be a home to singularities. It is generally agreed the primordial singularities were created shortly after the Big Bang, and exist in unknown numbers today. Presence of these objects in the Solar System's formation would have seeded formation of planetesimals and larger bodies. Their hidden presence would explain both planetary magnetic fields and internal heat sources. They would also explain the Ring's presence and longetivity. The most convincing evidence for singularities would be radiation discharge. Observation of a polar "hot spot" on Enceladus can not be explained by old theories of radioactive decay. The only feasible source of such heating in a small body is radiation from a central singularity. Further observations of Ring objects may show more direct evidence. Discovery of singularities in our Solar System would have huge benefits. It allows us to solve problems of Earth's formation and behaviour. Study of such objects would allow us to observe Hawking radiation and other predictions of quantum theory. Finally, harnessing of their energy would have immense value for physics and energy on Earth.

The processes that lead to charging of dust grains in a plasma are briefly reviewed. Whereas for single grains the results have been long known, the reduction of the average charge on a grain by “Debye screening” has only recently been discovered. This reduction can be important in the Jovian ring and in the rings of Uranus. The emerging field of gravitoelectrodynamics which deals with the motion of charged grains in a planetary magnetosphere is then reviewed. Important mechanisms for distributing grains in radial distance are due to stochastic fluctuations of the grain charge and a systematic variation due to motion through plasma gradients. The electrostatic levitation model for the formation of spokes is discussed, and it is shown that the radial transport of dust contained in the spokes may be responsible for the rich radial structure in Saturn's rings. Finally, collective effects in dusty plasmas are discussed which affect various waves, such as density waves in planetary ...

The study of planetary ring systems is a key component of planetary science for several reasons: 1) The evolution and current states of planets and their satellites are affected in many ways by rings, while 2) conversely, properties of planets and moons and other solar system populations are revealed by their effects on rings; 3) highly structured and apparently delicate ring systems may be bellwethers, constraining various theories of the origin and evolution of their entire planetary system; and finally, 4) planetary rings provide ...

Nonlinear properties of small amplitude dust acoustic waves, incorporatingboth the ion inertial effect and dust drift effect have been studied. The effect of dust charge variation is also incorporated. It is seen thatdue to the dust charge variation, a Korteweg-de Vries ( ...

The MIMI investigation comprises three sensors: the Ion and Neutral Camera (INCA) provides images using energetic neutral atoms (ENA) and ions; the Charge-Energy-Mass-Spectrometer (CHEMS) determines the mass and charge state of ions; and the Low Energy Magnetospheric Measurement System (LEMMS) measures ion and electron distributions using a dual field-of-view telescope (Krimigis et al., 2004). Measurements by MIMI following Saturn orbit insertion on 1 July 2004 revealed: (1) a dynamical magnetosphere with a day-night asymmetry and an 11-hour periodicity; (2) several water-product ions (O+, OH+, H2O+), but little N+; (3) inferred quantities of neutral gas sufficient to cause major losses in the trapped ions and electrons in the middle and inner magnetosphere; (4) a Titan exosphere that is a copious source of energetic neutral atoms (ENA); (5) a previously unknown radiation belt residing inward of the D-ring that is most likely the result of double charge-exchange between the main rad...

The study of planetary ring systems is a key component of planetary science for several reasons: 1) The evolution and current states of planets and their satellites are affected in many ways by rings, while 2) conversely, properties of planets and moons and other solar system populations are revealed by their effects on rings; 3) highly structured and apparently delicate ring systems may be bellwethers, constraining various theories of the origin and evolution of their entire planetary system; and finally, 4) planetary rings provide ...

The study of planetary ring systems is a key component of planetary science for several reasons: 1) The evolution and current states of planets and their satellites are affected in many ways by rings, while 2) conversely, properties of planets and moons and other solar system populations are revealed by their effects on rings; 3) highly structured and apparently delicate ring systems may be bellwethers, constraining various theories of the origin and evolution of their entire planetary system; and finally, 4) planetary rings provide ...

The interactions among objects in a mean motion resonance are important for the orbital evolution of satellites and rings, especially Saturn's ring arcs and associated moons. In this work, we examine interactions among massive bodies in the same corotation eccentricity resonance site that affect the orbital evolution of those bodies using numerical simulations. During these simulations, the bodies exchange angular momentum and energy during close encounters, altering their orbits. This energy exchange, however, does not mean that one body necessarily moves closer to exact corotation when the other moves away from it. Indeed, if one object moves toward one of these sites, the other object is equally likely to move toward or away from it. This happens because the timescale of these close encounters is short compared to the synodic period between these particles and the secondary mass (i.e., the timescale where corotation sites can be treated as potential maxima). Because the timescale of a gravitational encounter is comparable to the timescale of a collision, we could expect energy to be exchanged in a similar way for collisional interactions. In that case, these findings could be relevant for denser systems like the arcs in Neptune's Adams ring and how they can be maintained in the face of frequent inelastic collisions.