Search Publications
The importance of plasma β conditions for magnetic reconnection at Saturn's magnetopause
Coates, A. J.; Russell, C. T.; Dougherty, M. K. +7 more
Magnetic reconnection is an important process that occurs at the magnetopause boundary of Earth's magnetosphere because it leads to transport of solar wind energy into the system, driving magnetospheric dynamics. However, the nature of magnetopause reconnection in the case of Saturn's magnetosphere is unclear. Based on a combination of Cassini spa…
Enceladus' extreme heat flux as revealed by its relaxed craters
Singer, Kelsi N.; Schenk, Paul M.; McKinnon, William B. +1 more
Enceladus' cratered terrains contain large numbers of unusually shallow craters consistent with deformation by viscous relaxation of water ice under conditions of elevated heat flow. Here we use high-resolution topography to measure the relaxation fraction of craters on Enceladus far from the active South Pole. We find that many craters are shallo…
Is Titan's shape caused by its meteorology and carbon cycle?
Sotin, C.; Choukroun, M.
Titan's shape is characterized by a difference between the long equatorial radius and the polar radius that is several hundred meters larger than that predicted by the flattening due to its spin rate. The North polar region is covered by large mare filled with hydrocarbons, including ethane. Moreover global circulation models predict ethane precip…
Detection of negative ions in the deep ionosphere of Titan during the Cassini T70 flyby
Wahlund, J. -E.; Edberg, N. J. T.; Ågren, K.
We present radio and plasma wave science (RPWS) Langmuir probe (LP) observations that give evidence for a population of heavy, negative ions at altitudes below 900 km in Titan's ionosphere during the Cassini T70 flyby. The negative ion density in this region is comparable to, or higher than, the electron density of 760 cm-3. Both positi…
Detection of exospheric O2+ at Saturn's moon Dione
Coates, A. J.; Thomsen, M. F.; Wilson, R. J. +6 more
During a close pass of Cassini through the plasma wake of Saturn's moon Dione on April 7, 2010 the Cassini Plasma Spectrometer (CAPS) detected molecular oxygen ions (O2+) on pick up ring velocity distributions, thus providing the first in situ detection of a neutral exosphere surrounding the icy moon. The density of O2
Peak emission altitude of Saturn's H3+ aurora
Baines, Kevin H.; Brown, Robert H.; Melin, Henrik +3 more
Here we present the first detailed measurement of the altitudinal profile of H3+ emission within Saturn's ionosphere, made using images taken by the VIMS instrument on Cassini on 11-12 October 2006, during a chance alignment between the visible limb of the planet and the position of the main auroral emission. Using this, we s…
On the Edgeworth-Kuiper Belt dust flux to Saturn
Horányi, Mihály; Poppe, Andrew R.
Dust grains originating from the Edgeworth-Kuiper Belt (EKB) are believed to be the dominant species of dust in the outer solar system. These grains, evolving inward from the EKB under the influence of a variety of forces, will encounter the giant planets or their ring and moon systems. At Saturn, this influx drives several physical processes incl…
Titan airglow during eclipse
Strobel, D. F.; West, R. A.; Gladstone, G. R. +4 more
Solar XUV photons can provide enough energy to account for the observed nitrogen UV dayglow emissions above 800 km, but a small or sporadic contribution from energetic particles cannot be ruled out. Furthermore, ion production at altitudes deeper than 800 km as inferred from radio occultation cannot be produced by solar XUV stimulation and implies…
The observed composition of ions outflowing from Titan
Luhmann, J. G.; Mitchell, D. G.; Wahlund, J. -E. +8 more
We report on Cassini Ion and Neutral Mass Spectrometer (INMS) observations above Titan's exobase at altitudes of 2225 km to 3034 km. We observe significant densities of CH5+, HCNH+ and C2H5+ that require ion-molecule reactions to be produced in the quantities observed. The measured …
Spacecraft charging near Enceladus
Kempf, S.; Grün, E.; Hsu, H. -W. +1 more
In the vicinity of Enceladus, a geologically active moon of Saturn, the modeled spacecraft potential is significantly more negative than indicated by the Cassini Langmuir probe measurements. To understand this potential difference, we introduce two new dust-related charging currents: a) the dust ram current; and b) the dust impact-plasma current, …