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Solar control of radar wave absorption by the Martian ionosphere
Gurnett, D. A.; Morgan, D. D.; Plaut, J. J. +6 more
The MARSIS active sounder aboard the Mars Express spacecraft, under certain conditions in the Martian ionosphere, fails to detect the planetary surface. We have generated a statistical measure of the surface reflection visibility, which we plot as a time series and compare with both in situ particle data taken at Mars and solar x-ray data taken at…
Hydrogen exosphere at Mars: Pickup protons and their acceleration at the bow shock
Barabash, S.; Lundin, R.; Yamauchi, M. +3 more
Pickup protons (PIs) with a ring-beam distribution originating from the extended hydrogen exosphere of Mars are observed by the ASPERA-3 experiment onboard the Mars Express spacecraft at solar minimum conditions. PIs can contribute ~1% to the solar wind number density at close distances to the flank bow shock. The observed fluxes of PIs indicate t…
Substorm associated magnetotail energetic electrons pitch angle evolutions and flow reversals: Cluster observation
Lucek, E.; Fritz, T. A.; Wu, P. +1 more
The Cluster satellites observed a distinct pattern in the evolution of energetic electron pitch angle distributions on November 13, 2003, in the mid-tail (radius >10RE) associated with intensifications of these electron fluxes that accompanied an observed local dipolarization of the magnetic field. The intensity of electrons (20-200 …
Dust devils on Mars observed by the High Resolution Stereo Camera
Greeley, Ronald; Pätzold, Martin; Neukum, Gerhard +2 more
Fourteen active dust devils were observed by the High Resolution Stereo Camera (HRSC) on Mars Express, which enable the first analysis of the forward speed of dust devils on Mars determined from orbit. Results show speeds on the order of 20 m/s, which compares favorably with values of the wind profiles estimated from the Martian Climate Database f…
Cassini radio occultations of Saturn's ionosphere: Model comparisons using a constant water flux
Moore, Luke; Kliore, Arvydas J.; Mendillo, Michael +3 more
Recent radio occultations of Saturn's equatorial ionosphere by the Cassini spacecraft provide important insight into this poorly constrained region. Twelve new electron density profiles identify a clear dawn/dusk asymmetry as well as two apparently separate electron density peaks. This study uses a 3D general circulation model along with 1D water …
Geologically recent tectonic, volcanic and fluvial activity on the eastern flank of the Olympus Mons volcano, Mars
Head, J. W.; Neukum, G.; van Gasselt, S. +4 more
We show evidence of very recent (<=25-40 Myr) geologic activity on the eastern flank of Olympus Mons volcano that includes a suite of fluvial (channel networks), volcanic (emplacement of lava flows and dikes), and tectonic (wrinkle ridges and troughs) processes. The combination and youth of these features confirms the importance of geological a…
Cluster PEACE observations of electron pressure tensor divergence in the magnetotail
Lucek, E.; Fazakerley, A. N.; Owen, C. J. +4 more
Cluster crossed the magnetotail neutral sheet on four occasions between 16:38 and 16:43 UT on 08/17/2003. The four-spacecraft capabilities of Cluster are used to determine spatial gradients from the magnetic field vectors and, for the first time, full electron pressure tensors. We find that the contribution to the electric field from the Hall term…
A global magnetic model of Saturn's magnetosphere and a comparison with Cassini SOI data
Alexeev, I. I.; Belenkaya, E. S.; Nichols, J. D. +4 more
A re-scaling of a recent model of Jupiter's magnetosphere incorporating ring current, magnetopause, and tail current systems is used as a starting-point for modeling Saturn's magnetospheric field. The model is compared with observations obtained by Cassini during its Saturn orbit insertion fly-through of Saturn's magnetosphere, and is shown to giv…
Electrostatic solitary structures observed at Saturn
Gurnett, D. A.; Dougherty, M. K.; Kurth, W. S. +2 more
We report observations of electric field solitary structures, measured by the Cassini Radio and Plasma Wave Science (RPWS) instrument in the vicinity of Saturn's magnetosphere with ambient magnetic fields that range from ~0.1 nT to 8000 nT. The peak-to-peak electric field amplitudes of the observed solitary structures range from a few µV/m t…
Europa's FUV auroral tail on Jupiter
Clarke, J. T.; Mauk, B. H.; Gérard, J. -C. +3 more
Ultraviolet images of Jupiter's northern aurora obtained in 2005 confirm the existence of an electromagnetic interaction between Europa and the Jovian ionosphere. The auroral signature shows a two-component structure: a quasi-circular Europa spot, followed by a previously undetected faint tail emission trailing in the direction of corotation flow.…