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Radar Soundings of the Ionosphere of Mars
Gurnett, D. A.; Persoon, A. M.; Averkamp, T. F. +8 more
We report the first radar soundings of the ionosphere of Mars with the MARSIS (Mars Advanced Radar for Subsurface and Ionosphere Sounding) instrument on board the orbiting Mars Express spacecraft. Several types of ionospheric echoes are observed, ranging from vertical echoes caused by specular reflection from the horizontally stratified ionosphere…
Radio and Plasma Wave Observations at Saturn from Cassini's Approach and First Orbit
Gurnett, D. A.; Persoon, A. M.; Hospodarsky, G. B. +24 more
We report data from the Cassini radio and plasma wave instrument during the approach and first orbit at Saturn. During the approach, radio emissions from Saturn showed that the radio rotation period is now 10 hours 45 minutes 45 +/- 36 seconds, about 6 minutes longer than measured by Voyager in 1980 to 1981. In addition, many intense impulsive rad…
Cassini Radar Views the Surface of Titan
Stiles, B.; Kelleher, K.; Callahan, P. +32 more
The Cassini Titan Radar Mapper imaged about 1% of Titan's surface at a resolution of ~0.5 kilometer, and larger areas of the globe in lower resolution modes. The images reveal a complex surface, with areas of low relief and a variety of geologic features suggestive of dome-like volcanic constructs, flows, and sinuous channels. The surface appears …
Cassini Magnetometer Observations During Saturn Orbit Insertion
Russell, C. T.; Dougherty, M. K.; Balogh, A. +15 more
Cassini's successful orbit insertion has provided the first examination of Saturn's magnetosphere in 23 years, revealing a dynamic plasma and magnetic environment on short and long time scales. There has been no noticeable change in the internal magnetic field, either in its strength or its near-alignment with the rotation axis. However, the exter…
Cassini Measurements of Cold Plasma in the Ionosphere of Titan
Gurnett, D. A.; Persoon, A. M.; Dougherty, M. K. +15 more
The Cassini Radio and Plasma Wave Science (RPWS) Langmuir probe (LP) sensor observed the cold plasma environment around Titan during the first two flybys. The data show that conditions in Saturn's magnetosphere affect the structure and dynamics deep in the ionosphere of Titan. The maximum measured ionospheric electron number density reached 3800 p…
Spectral Reflectance and Morphologic Correlations in Eastern Terra Meridiani, Mars
Mangold, N.; Bibring, J. -P.; Arvidson, R. E. +7 more
The Mars Express Observatoire pour la Minéralogie, l'Eau, les Glaces, et l'Activité (OMEGA) hyperspectral image data covering eastern Terra Meridiani indicate the ubiquitous presence of molecular water in etched terrain materials that disconformably overlie heavily cratered terrains and underlie the hematite-bearing plains explored by the Opportun…
Cassini Imaging Science: Initial Results on Phoebe and Iapetus
Burns, J. A.; Neukum, G.; Wagner, R. +32 more
The Cassini Imaging Science Subsystem acquired high-resolution imaging data on the outer Saturnian moon, Phoebe, during Cassini's close flyby on 11 June 2004 and on Iapetus during a flyby on 31 December 2004. Phoebe has a heavily cratered and ancient surface, shows evidence of ice near the surface, has distinct layering of different materials, and…
Cassini Imaging Science: Initial Results on Saturn's Rings and Small Satellites
Burns, J. A.; Neukum, G.; Wagner, R. +32 more
Images acquired of Saturn's rings and small moons by the Cassini Imaging Science Subsystem (ISS) during the first 9 months of Cassini operations at Saturn have produced many new findings. These include new saturnian moons; refined orbits of new and previously known moons; narrow diffuse rings in the F-ring region and embedded in gaps within the ma…
A Sporadic Third Layer in the Ionosphere of Mars
Pätzold, M.; Häusler, B.; Tellmann, S. +3 more
The daytime martian ionosphere has been observed as a two-layer structure with electron densities that peak at altitudes between about 110 and 130 kilometers. The Mars Express Orbiter Radio Science Experiment on the European Mars Express spacecraft observed, in 10 out of 120 electron density profiles, a third ionospheric layer at altitude ranges o…
Temperatures, Winds, and Composition in the Saturnian System
Strobel, D. F.; Showalter, M. R.; Lellouch, E. +43 more
Stratospheric temperatures on Saturn imply a strong decay of the equatorial winds with altitude. If the decrease in winds reported from recent Hubble Space Telescope images is not a temporal change, then the features tracked must have been at least 130 kilometers higher than in earlier studies. Saturn's south polar stratosphere is warmer than pred…