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Compositional maps of Saturn's moon Phoebe from imaging spectroscopy
Sotin, C.; Baines, K. H.; Nicholson, P. D. +23 more
The origin of Phoebe, which is the outermost large satellite of Saturn, is of particular interest because its inclined, retrograde orbit suggests that it was gravitationally captured by Saturn, having accreted outside the region of the solar nebula in which Saturn formed. By contrast, Saturn's regular satellites (with prograde, low-inclination, ci…
Evidence from the Mars Express High Resolution Stereo Camera for a frozen sea close to Mars' equator
HRSC Co-Investigator Team; Head, James W.; van Gasselt, Stephan +10 more
It is thought that the Cerberus Fossae fissures on Mars were the source of both lava and water floods two to ten million years ago. Evidence for the resulting lava plains has been identified in eastern Elysium, but seas and lakes from these fissures and previous water flooding events were presumed to have evaporated and sublimed away. Here we pres…
The vertical profile of winds on Titan
Plettemeier, D.; Gurvits, L. I.; Pogrebenko, S. V. +12 more
One of Titan's most intriguing attributes is its copious but featureless atmosphere. The Voyager 1 fly-by and occultation in 1980 provided the first radial survey of Titan's atmospheric pressure and temperature and evidence for the presence of strong zonal winds. It was realized that the motion of an atmospheric probe could be used to study the wi…
Morphological differences between Saturn's ultraviolet aurorae and those of Earth and Jupiter
Kim, J.; Hill, T.; Crary, F. +10 more
It has often been stated that Saturn's magnetosphere and aurorae are intermediate between those of Earth, where the dominant processes are solar wind driven, and those of Jupiter, where processes are driven by a large source of internal plasma. But this view is based on information about Saturn that is far inferior to what is now available. Here w…
Solar wind dynamic pressure and electric field as the main factors controlling Saturn's aurorae
Coates, A. J.; Dougherty, M. K.; Kurth, W. S. +11 more
The interaction of the solar wind with Earth's magnetosphere gives rise to the bright polar aurorae and to geomagnetic storms, but the relation between the solar wind and the dynamics of the outer planets' magnetospheres is poorly understood. Jupiter's magnetospheric dynamics and aurorae are dominated by processes internal to the jovian system, wh…
In situ multi-satellite detection of coherent vortices as a manifestation of Alfvénic turbulence
Sundkvist, David; Vaivads, Andris; Krasnoselskikh, Vladimir +4 more
Turbulence in fluids and plasmas is a ubiquitous phenomenon driven by a variety of sources-currents, sheared flows, gradients in density and temperature, and so on. Turbulence involves fluctuations of physical properties on many different scales, which interact nonlinearly to produce self-organized structures in the form of vortices. Vortex motion…
A soft solid surface on Titan as revealed by the Huygens Surface Science Package
Banaszkiewicz, Marek; Zarnecki, John C.; Lorenz, Ralph D. +23 more
The surface of Saturn's largest satellite-Titan-is largely obscured by an optically thick atmospheric haze, and so its nature has been the subject of considerable speculation and discussion. The Huygens probe entered Titan's atmosphere on 14 January 2005 and descended to the surface using a parachute system. Here we report measurements made just a…
Saturn's moon Phoebe as a captured body from the outer Solar System
Lunine, Jonathan I.; Johnson, Torrence V.
The orbital properties of Phoebe, one of Saturn's irregular moons, suggest that it was captured by the ringed planet's gravitational field rather than formed in situ. Phoebe's generally dark surface shows evidence of water ice, but otherwise the surface most closely resembles that of C-type asteroids and small outer Solar System bodies such as Chi…
An Earth-like correspondence between Saturn's auroral features and radio emission
Gurnett, D. A.; Dougherty, M. K.; Kurth, W. S. +12 more
Saturn is a source of intense kilometre-wavelength radio emissions that are believed to be associated with its polar aurorae, and which provide an important remote diagnostic of its magnetospheric activity. Previous observations implied that the radio emission originated in the polar regions, and indicated a strong correlation with solar wind dyna…
Discovery of a flank caldera and very young glacial activity at Hecates Tholus, Mars
HRSC Co-Investigator Team; Head, James W.; Greeley, Ronald +8 more
The majority of volcanic products on Mars are thought to be mafic and effusive. Explosive eruptions of basic to ultrabasic chemistry are expected to be common, but evidence for them is rare and mostly confined to very old surface features. Here we present new image and topographic data from the High Resolution Stereo Camera that reveal previously …