Aggregate dust particles at comet 67P/Churyumov-Gerasimenko.

Comets are thought to preserve almost pristine dust particles, thus providing a unique sample of the properties of the early solar nebula. The microscopic properties of this dust played a key part in particle aggregation during the formation of the Solar System. Cometary dust was previously considered to comprise irregular, fluffy agglomerates on the basis of interpretations of remote observations in the visible and infrared and the study of chondritic porous interplanetary dust particles that were thought, but not proved, to originate in comets.

On the detection of mesospheric meteoric smoke particles embedded in noctilucent cloud particles with rocket-borne dust probes.

Mesospheric nanoparticles in the forms of water ice particles and meteoric smoke particles (MSPs) exist in the middle atmosphere where they often play a decisive role in cloud formation and in chemical processes. Direct in situ observations of mesospheric nanoparticles have been made possible by rocket probes developed during the last two decades. Although progress has been made in mapping properties such as electric charge, sizes, and interaction with the plasma and neutral gas, more observations are needed on the size distribution, chemical content, and structure of the MSP to determine their role in cloud formation and chemistry in the mesosphere and stratosphere.

In-flight calibration of mesospheric rocket plasma probes.

Many effects and factors can influence the efficiency of a rocket plasma probe. These include payload charging, solar illumination, rocket payload orientation and rotation, and dust impact induced secondary charge production. As a consequence, considerable uncertainties can arise in the determination of the effective cross sections of plasma probes and measured electron and ion densities.

Saturn's spokes: lost and found.

The spokes are intermittently appearing radial markings in Saturn's B ring that are believed to form when micrometer-sized dust particles are levitated above the ring by electrostatic forces. First observed by the Voyagers, the spokes disappeared from October 1998 until September 2005, when the Cassini spacecraft saw them reappear. The trajectories of the charged dust particles comprising the spokes depend critically on the background plasma density above the rings, which is a function of the solar elevation angle.

Origin of the curved nature of Mach cone wings in complex plasmas.

While the propagation and refraction of waves and shocks which constitute Mach cones have been well studied in continuous slowly varying stratified media such as gases, liquids, and solids, here we investigate these processes at the kinetic, discrete (or "molecular") level in a complex plasma where the stratification scale is of the order of the damping length. The shape of Mach cones formed by nondispersive linear sound waves in a nonuniform complex plasma was calculated analytically using the method of wave rays. The cases of transversely and longitudinally inhomogeneous media as well as a medium with a sound speed maximum were considered.