A5072336227- Astro and Planetary Science
- Planetary Science and Exploration
- Astrophysics and Star Formation Studies
- Spacecraft and Cryogenic Technologies
- Space Exploration and Technology
- Stellar, planetary, and galactic studies
- Rocket and propulsion systems research
- Marine and environmental studies
- High-pressure geophysics and materials
- Geomagnetism and Paleomagnetism Studies
- Spacecraft Dynamics and Control
- Dielectric materials and actuators
- Ionosphere and magnetosphere dynamics
- Aerospace Engineering and Energy Systems
- Advanced Sensor and Energy Harvesting Materials
- Geology and Paleoclimatology Research
- Ancient Near East History
- Fluid dynamics and aerodynamics studies
- Solar and Space Plasma Dynamics
- Bone health and treatments
- Cancer Diagnosis and Treatment
- Dermatological and Skeletal Disorders
- Diffusion Coefficients in Liquids
- High voltage insulation and dielectric phenomena
- Atmospheric aerosols and clouds
University of Potsdam
2007-2019
Friedrich-Alexander-Universität Erlangen-Nürnberg
2009
Max Planck Institute for Nuclear Physics
2006-2008
Max Planck Institute for Solar System Research
2008
University College London
2008
Southwest Research Institute
2008
University of Colorado Boulder
2006
Friedrich Schiller University Jena
2006
University of Hawaii System
2006
Laboratory for Atmospheric and Space Physics
2006
During Cassini's close flyby of Enceladus on 14 July 2005, the High Rate Detector Cosmic Dust Analyzer registered micron-sized dust particles enveloping this satellite. The impact rate peaked about 1 minute before closest approach spacecraft to moon. This asymmetric signature is consistent with a locally enhanced production in south polar region Enceladus. Other Cassini experiments revealed evidence for geophysical activities near Enceladus' pole: high surface temperature and release water...
Cassini's final phase of exploration The Cassini spacecraft spent 13 years orbiting Saturn; as it ran low on fuel, the trajectory was changed to sample regions had not yet visited. A series orbits close rings followed by a Grand Finale orbit, which took through gap between Saturn and its before destroyed when entered planet's upper atmosphere. Six papers in this issue report results from these phases mission. Dougherty et al. measured magnetic field Saturn, implies complex multilayer dynamo...
Porous polytetrafluoroethylene (PTFE) films were positively or negatively corona charged at room elevated temperatures. Their charge storage behavior was investigated by means of isothermal surface potential measurements in direct comparison to nominally nonporous samples the same polymer. It found that porosity may lead significantly enhanced surface-charge stability for both polarities. Direct piezoelectricity studied on quadruple, double, and single layer quasi-static measurements. For...
Saturn's moon Rhea had been considered massive enough to retain a thin, externally generated atmosphere capable of locally affecting magnetosphere. The Cassini spacecraft's in situ observations reveal that energetic electrons are depleted the moon's vicinity. absence substantial exosphere implies Rhea's magnetospheric interaction region, rather than being exclusively induced by sputtered gas and its products, likely contains solid material can absorb particles. Combined from several...
Particle simulations are carried out to study density features caused by small moonlets embedded in a dense planetary ring. The creation of “propeller” like structure is found together with adjacent wakes. Both clear indications for the existence rings. We confirmed that propeller scales Hill‐radius radial direction whereas its azimuthal extent determined ratio between moonlet‐mass and ring‐viscosity. Our findings bear direct implications analysis Cassini imaging (ISS) occultation (UVIS)...
Cassini's last look at Saturn's rings During the final stages of Cassini mission, spacecraft flew between planet and its rings, providing a new view on this spectacular system (see Perspective by Ida). Setting scene, Spilker reviews numerous discoveries made using during 13 years it spent orbiting Saturn. Iess et al. measured gravitational pull Cassini, separating contributions from rings. This allowed them to determine interior structure Saturn mass Buratti present observations five small...
Two images, taken by the Cassini spacecraft near Saturn's equinox in 2009 August, show Earhart propeller casting a 350 km long shadow, offering opportunity to watch how ring height, excited moonlet, relaxes an equilibrium state. From shape of shadow cast and model azimuthal height relaxation, we determine exponential cooling constant this process be λ = 0.07 ± 0.02 km−1, thereby collision frequency particles vertically region ωc/Ω 0.9 0.2.
Abstract The reconstruction of the orbital evolution propeller structure Blériot orbiting in Saturn’s A ring from recurrent observations Cassini ISS images yielded a considerable offset motion expected Keplerian orbit. This can be composed by three sinusoidal harmonics with amplitudes and periods 1845, 152, 58 km 11.1, 3.7, 2.2 years, respectively. In this paper we present results N -body simulations, where integrated moonlet, which is placed at radial position under gravitational action...
Abstract Dust particles in the Saturn system can be detected by Radio and Plasma Wave Science (RPWS) instrument on board Cassini via antenna voltage signals induced dust impacts. These impact have been simulated laboratory accelerating onto a model with electric field antennas. RPWS measurements shown to consistent Cosmic Analyzer. During Grand Finale orbits, flew through gap between D ring Saturn's atmosphere 22 times. In situ helped quantify hazards posed spacecraft instruments board,...
Abstract During the Ring Grazing orbits near end of Cassini mission, spacecraft crossed equatorial plane orbit Janus/Epimetheus (~2.5 Rs ). This region is populated with dust particles that can be detected by Radio and Plasma Wave Science (RPWS) instrument via an electric field antenna signal. Analysis voltage waveforms recorded on RPWS antennas provides estimations density size distribution particles. Measured profiles, fitted Lorentzian functions, are shown to mostly consistent Cosmic Dust...
Porous PTFE films were corona charged with high voltages at room and elevated temperatures their direct inverse piezoelectric coefficients determined. In both cases, d/sub 33/ of up to 600 pC/N found. These values are more than one order magnitude higher those conventional polymers such as poly(vinylidene fluoride). They comparable the inorganic piezoelectrics recently developed porous polypropylene electrets, but have added advantage a much better thermal stability.
Abstract One of the biggest successes Cassini mission is detection small moons (moonlets) embedded in Saturns rings that cause S-shaped density structures their close vicinity, called propellers. Here, we present isothermal hydrodynamic simulations moonlet-induced propellers Saturn’s A ring denote a further development original model. We find excellent agreement between these new and corresponding N -body simulations. Furthermore, confirm predicted scaling laws analytical solution for...
The space missions Voyager and Cassini together with earthbound observations revealed a wealth of structures in Saturn’s rings. There are, for example, waves being excited at ring positions which are orbital resonance moons. Other can be assigned to embedded moons like empty gaps, moon induced wakes or S-shaped propeller features. Furthermore, irregular radial observed the range from 10 meters until kilometers. Here some these will discussed frame hydrodynamical modeling dense For this...
Abstract We develop an axisymmetric diffusion model to describe radial density profiles in the vicinity of tiny moons embedded planetary rings. Our accounts for gravitational scattering ring particles by moon and viscous matter back into gap. With test particle simulations, we show that passing is larger small impact parameters than estimated Goldreich & Tremaine Namouni. This significant modeling Keeler apply our gaps Pan Daphnis outer A Saturn with aim estimate shear viscosity Encke In...