Search Publications
Active volcanism on Venus in the Ganiki Chasma rift zone
Head, J. W.; Ignatiev, N. I.; Basilevsky, A. T. +3 more
Venus is known to have been volcanically resurfaced in the last third of solar system history and to have undergone a significant decrease in volcanic activity a few hundred million years ago. However, fundamental questions remain: Is Venus still volcanically active today, and if so, where and in what geological and geodynamic environment? Here we…
Effect of Enceladus's rapid synchronous spin on interpretation of Cassini gravity
McKinnon, William B.
Enceladus's degree 2 gravity, determined by Cassini, is nominally nonhydrostatic to 3σ (J2/C22 = 3.38-3.63, as opposed to 10/3). Iess et al. (2014) interpret this in terms of a hydrostatic interior (core) and isostatic (not hydrostatic) floating ice shell. Enceladus's rapid (1.37 d) synchronous spin and tide distorts its shap…
Spatial distribution of low-energy plasma around comet 67P/CG from Rosetta measurements
Glassmeier, K. -H.; Szego, K.; Nilsson, H. +22 more
We use measurements from the Rosetta plasma consortium Langmuir probe and mutual impedance probe to study the spatial distribution of low-energy plasma in the near-nucleus coma of comet 67P/Churyumov-Gerasimenko. The spatial distribution is highly structured with the highest density in the summer hemisphere and above the region connecting the two …
A strong seasonal dependence in the Martian hydrogen exosphere
Bertaux, Jean-Loup; Chaufray, Jean-Yves; Clarke, John T. +2 more
Hubble Space Telescope and Mars Express observed unexpected rapid changes in the Martian hydrogen exosphere involving a decrease in scattered Lyman α intensity in fall 2007 (solar longitude, Ls = 331°-345°). These changes detected were speculated to be a combination of seasonal variation and/or dust storms and lower atmospheric dynamics…
Fractures on comet 67P/Churyumov-Gerasimenko observed by Rosetta/OSIRIS
Jorda, L.; Lamy, P. L.; Lara, L. M. +50 more
The Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS) experiment onboard the Rosetta spacecraft currently orbiting comet 67P/Churyumov-Gerasimenko has yielded unprecedented views of a comet's nucleus. We present here the first ever observations of meter-scale fractures on the surface of a comet. Some of these fractures form polyg…
Electrostatic solitary waves with distinct speeds associated with asymmetric reconnection
André, M.; Vaivads, A.; Khotyaintsev, Yu. V. +1 more
Electrostatic solitary waves (ESWs) are observed at the magnetopause with distinct time scales. These ESWs are associated with asymmetric reconnection of the cold dense magnetosheath plasma with the hot tenuous magnetospheric plasma. The distinct time scales are shown to be due to ESWs moving at distinct speeds and having distinct length scales. T…
Possible evidence for a methane source in Enceladus' ocean
Mousis, Olivier; Bouquet, Alexis; Waite, J. Hunter +1 more
The internal ocean of Enceladus can be expected to present conditions favorable to the trapping of volatiles in clathrates. This process could influence the eventual composition of the ocean and therefore of the plumes emitted by the south polar region. Here we used a statistical thermodynamic model to assess which species detected in the plumes b…
Transient internally driven aurora at Jupiter discovered by Hisaki and the Hubble Space Telescope
Hasegawa, H.; Fujimoto, M.; Masters, A. +12 more
Jupiter's auroral emissions reveal energy transport and dissipation through the planet's giant magnetosphere. While the main auroral emission is internally driven by planetary rotation in the steady state, transient brightenings are generally thought to be triggered by compression by the external solar wind. Here we present evidence provided by th…
Laboratory measurements of cryogenic liquid alkane microwave absorptivity and implications for the composition of Ligeia Mare, Titan
Lorenz, Ralph D.; Lunine, Jonathan I.; Mitchell, Karl L. +2 more
The complex dielectric constants of liquids methane and ethane were measured at 90 K and 14.1 GHz, close to the frequency of the Cassini RADAR. The liquid ethane loss tangent is far greater than that of liquid methane, facilitating discrimination by remote sensing. The results suggest a methane-dominated composition for the northern sea, Ligeia Ma…
Modification of the Hall physics in magnetic reconnection due to cold ions at the Earth's magnetopause
André, M.; Vaivads, A.; Toledo-Redondo, S. +1 more
Magnetic reconnection is a process permitting mass and energy exchange across plasma boundaries and converting magnetic energy into particle kinetic energy. Strong electric fields and currents due to the Hall effect are set up in narrow regions where ions are demagnetized but electrons remain magnetized. It has been recently shown that cold (few e…