Search Publications
Vertical atmospheric flow on Titan as measured by the HASI instrument on board the Huygens probe
Tokano, Tetsuya; Ferri, Francesca; Mäkinen, J. Teemu T. +3 more
On January 14, 2005, the Huygens probe descended on the surface of Titan, the largest moon of Saturn and the only moon in the Solar system with a substantial atmosphere. After the deployment of the main parachute and the release of the heat shield at an altitude of about 150 km, the local pressure and temperature were measured by HASI (Huygens Atm…
New multi-fluid MHD model of comet 26P/Grigg-Skjellerup: Extrapolation to comet 67P/Churyumov-Gerasimenko
Benna, M.; Mahaffy, P. R.
The Multi-fluid MHD simulator CASIM3D models the atmosphere of comet 26P/Grigg-Skjellerup as it was seen by the Giotto spacecraft during its flyby of the comet in July 1992. CASIM3D integrates the major chemical reactions and physical interactions to compute self-consistently over an adaptive Cartesian mesh the dynamics of ions, electrons, and neu…
Effects of nonlinearity on the structure of PSBL beamlets
Zelenyi, L. M.; Ashour-Abdalla, M.; Dolgonosov, M. S. +1 more
We investigate the nonlinear influence of the cross-tail currents carried by beamlets (substructures of PSBL ion beams) on the topology of the magnetic field, and, correspondingly, on the dispersion properties of these substructures self-consistently generated in this field. We found that some of the peculiarities of beamlet shapes found recently …
Mapping sub-pixel surface roughness on Mars using high-resolution satellite image data
Gillespie, Alan R.; Mushkin, Amit
The ratio between co-registered pixels in stereo or repeat image pairs is used to constrain the deviation of the Martian surface from Lambertian reflection due to unresolved shadows at the pixel scale of orbiting imagers. Relative differences between the ratios primarily reflect differences in the effective amount of shadows `seen' by the sensor i…
Reconstructing the weather on Mars at the time of the MERs and Beagle 2 landings
Withers, P.; Lewis, S. R.; Read, P. L. +1 more
We reconstruct the temperature, wind and density structure of the atmosphere on Mars from the surface to 120 km altitude at the time of the landing of the two NASA Mars Exploration Rovers (MER), and ESA's ``Beagle 2.'' This reconstruction is based on an assimilation of temperature and dust opacity observations from the Thermal Emission Spectromete…
Implication for the solar wind effect on the Io plasma torus
Kimura, T.; Misawa, H.; Yamamoto, H. +7 more
Sporadic enhancements of [SII] 673.1 nm emissions from the Io plasma torus were found in ground-based observations in 1998 and 1999. Just after the onset of the enhancement on September 21, 1999, narrow-band kilometric (nKOM) radiation began to be observed by the Galileo/PWS in the Jovian magnetosphere. During this period, quasi-periodic burst gro…
Assessment of the Martian gravity field at short wavelength with Mars Express
Pätzold, M.; Rosenblatt, P.; Le Maistre, S. +6 more
The gravity part of the Mars Express Radio Science Experiment consists in measuring gravity data near pericenter above selected target areas of geophysical interest. The low altitude of the Mars Express at pericenter (263-329 km) makes it a very sensitive gravity sensor at small wavelengths which can give new constraints on the local structure of …
Changing electrical nature of Saturn's rings: Implications for spoke formation
Gurnett, D. A.; Kurth, W. S.; Kaiser, M. L. +2 more
During Cassini's orbit insertion at Saturn, the trajectory took the spacecraft overtop the planet's famed ring system. At this time, the Cassini Radio and Plasma Wave Science (RPWS) instrument obtained unprecedented observations of electron density in the vicinity of the rings. Using this information and a model of photoemission anticipated from t…
Flow speed inside the brightness boundary of coronal streamers
Suess, S. T.; Nerney, S.
Density measurements in the legs of coronal streamers, where there might be outflow, are reproduced here using a magnetohydrodynamic model of the flow inside the brightness boundary of streamers. The model returns values for the flow speed and stream tube geometry (spreading) between the base and a few solar radii. The flow speed is consistent wit…
Discrimination between Jovian radio emissions and Saturn electrostatic discharges
Gurnett, D. A.; Kurth, W. S.; Fischer, G. +5 more
Short vertical streaks in the dynamic spectrum of the Cassini/RPWS (Radio and Plasma Wave Science) receiver in the frequency range of a few MHz can be due to Jovian radio emissions or SEDs (Saturn electrostatic discharges). Although Jupiter is increasingly far from Cassini, the peaks of decametric Jovian arcs can still be detected a few dB above t…