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Evidence for present day gully activity on the Russell crater dune field, Mars
Hiesinger, H.; Erkeling, G.; Reiss, D. +1 more
On the basis of High Resolution Imaging Science Experiment (HiRISE) images of two successive years we observed changes of a gully on the Russell crater dune field. Within the first year the length of a ∼2 m wide incised gully channel grew about 50 m downslope, and ∼120 m within in the second year. Gully activity occurred in early spring between L<…
Precise mass determination and the nature of Phobos
Pätzold, M.; Rosenblatt, P.; Häusler, B. +4 more
We report independent results from two subgroups of the Mars Express Radio Science (MaRS) team who independently analyzed Mars Express (MEX) radio tracking data for the purpose of determining consistently the gravitational attraction of the moon Phobos on the MEX spacecraft, and hence the mass of Phobos. New values for the gravitational parameter …
Energetic neutral atoms from the Earth's subsolar magnetopause
Wurz, P.; Reisenfeld, D. B.; McComas, D. J. +10 more
The shocked solar wind in the Earth's magnetosheath becomes nearly stationary at the subsolar magnetopause. At this location, solar wind protons are neutralized by charge exchange with neutral hydrogen atoms at the extreme limits of the Earth's tenuous exosphere. The resulting Energetic Neutral Atoms (ENAs) propagate away from the subsolar region …
Specular reflection on Titan: Liquids in Kraken Mare
Sotin, Christophe; Barnes, Jason W.; Soderblom, Jason M. +12 more
After more than 50 close flybys of Titan by the Cassini spacecraft, it has become evident that features similar in morphology to terrestrial lakes and seas exist in Titan's polar regions. As Titan progresses into northern spring, the much more numerous and larger lakes and seas in the north-polar region suggested by Cassini RADAR data, are becomin…
The reversal of the rotational modulation rates of the north and south components of Saturn kilometric radiation near equinox
Gurnett, D. A.; Persoon, A. M.; Kurth, W. S. +5 more
It has been known for many years that Saturn emits intense radio emissions at kilometer wavelengths and that this radiation is modulated by the rotation of the planet at a rate that varies slowly on time scales of years. Recently it has been shown that the radio emission consists of two components that have different rotational modulation rates, o…
Active shoreline of Ontario Lacus, Titan: A morphological study of the lake and its surroundings
Stofan, E.; Le Gall, A.; Mitchell, K. +18 more
Of more than 400 filled lakes now identified on Titan, the first and largest reported in the southern latitudes is Ontario Lacus, which is dark in both infrared and microwave. Here we describe recent observations including synthetic aperture radar (SAR) images by Cassini's radar instrument (λ = 2 cm) and show morphological evidence for active mate…
Link between EMIC waves in a plasmaspheric plume and a detached sub-auroral proton arc with observations of Cluster and IMAGE satellites
Lucek, E.; Frey, H. U.; Décréau, P. M. E. +7 more
In this paper, we report observations from a Cluster satellite showing that ULF wave occurred in the outer boundary of a plasmaspheric plume on September 4, 2005. The band of observed ULF waves is between the He+ ion gyrofrequency and O+ ion gyrofrequency at the equatorial plane, implying that those ULF waves can be identifie…
Variation of Saturn's UV aurora with SKR phase
Cecconi, B.; Lamy, L.; Nichols, J. D. +6 more
It is well known that a wide range of kronian magnetospheric phenomena, including the Saturn kilometric radiation (SKR), exhibit oscillations near the planetary rotation period. However, although the SKR is believed to be generated by unstable auroral electrons, no connection has been established to date between diurnal SKR modulations and UV auro…
Dawn-dusk oscillation of Saturn's conjugate auroral ovals
Lamy, L.; Nichols, J. D.; Cowley, S. W. H.
We present observations of the oscillation of the dawn-dusk locations of Saturn's northern and southern UV auroral ovals obtained using the Hubble Space Telescope during the 2009 equinoctial campaign. We determine the dawn-dusk locations of the centers of the southern and northern auroral ovals from the mean of the dawnward and duskward extents of…
Oxygen flux in the solar wind: Ulysses observations
Zurbuchen, Thomas H.; von Steiger, Rudolf; McComas, David J.
We use the complete set of Ulysses solar wind data to conduct a comprehensive determination of the oxygen flux in relation to the proton flux in the solar wind during a wide range of solar activity levels. The data cover the heliosphere between 1.3 and 5.4 AU and, due to the unique orbit of Ulysses, all of the heliographic latitudes within ±80°. W…