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Titan's Atmospheric Temperatures, Winds, and Composition
Strobel, D. F.; Showalter, M. R.; Lellouch, E. +42 more
Temperatures obtained from early Cassini infrared observations of Titan show a stratopause at an altitude of 310 kilometers (and 186 kelvin at 15°S). Stratospheric temperatures are coldest in the winter northern hemisphere, with zonal winds reaching 160 meters per second. The concentrations of several stratospheric organic compounds are enhanced a…
Solar Wind Origin in Coronal Funnels
Wilhelm, Klaus; Marsch, Eckart; Wang, Jing-Xiu +4 more
The origin of the solar wind in solar coronal holes has long been unclear. We establish that the solar wind starts flowing out of the corona at heights above the photosphere between 5 megameters and 20 megameters in magnetic funnels. This result is obtained by a correlation of the Doppler-velocity and radiance maps of spectral lines emitted by var…
Composition and Dynamics of Plasma in Saturn's Magnetosphere
Lewis, G. R.; Coates, A. J.; Linder, D. R. +40 more
During Cassini's initial orbit, we observed a dynamic magnetosphere composed primarily of a complex mixture of water-derived atomic and molecular ions. We have identified four distinct regions characterized by differences in both bulk plasma properties and ion composition. Protons are the dominant species outside about 9 RS (where R
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…