Search Publications
Assessment of the Martian gravity field at short wavelength with Mars Express
Pätzold, M.; Rosenblatt, P.; Le Maistre, S. +6 more
The gravity part of the Mars Express Radio Science Experiment consists in measuring gravity data near pericenter above selected target areas of geophysical interest. The low altitude of the Mars Express at pericenter (263-329 km) makes it a very sensitive gravity sensor at small wavelengths which can give new constraints on the local structure of …
Changing electrical nature of Saturn's rings: Implications for spoke formation
Gurnett, D. A.; Kurth, W. S.; Kaiser, M. L. +2 more
During Cassini's orbit insertion at Saturn, the trajectory took the spacecraft overtop the planet's famed ring system. At this time, the Cassini Radio and Plasma Wave Science (RPWS) instrument obtained unprecedented observations of electron density in the vicinity of the rings. Using this information and a model of photoemission anticipated from t…
Flow speed inside the brightness boundary of coronal streamers
Suess, S. T.; Nerney, S.
Density measurements in the legs of coronal streamers, where there might be outflow, are reproduced here using a magnetohydrodynamic model of the flow inside the brightness boundary of streamers. The model returns values for the flow speed and stream tube geometry (spreading) between the base and a few solar radii. The flow speed is consistent wit…
Discrimination between Jovian radio emissions and Saturn electrostatic discharges
Gurnett, D. A.; Kurth, W. S.; Fischer, G. +5 more
Short vertical streaks in the dynamic spectrum of the Cassini/RPWS (Radio and Plasma Wave Science) receiver in the frequency range of a few MHz can be due to Jovian radio emissions or SEDs (Saturn electrostatic discharges). Although Jupiter is increasingly far from Cassini, the peaks of decametric Jovian arcs can still be detected a few dB above t…
Shell-instability generated waves by low energy electrons on converging magnetic field lines
Vaivads, A.; Bogdanova, Y. V.; Décréau, P. M. E. +3 more
Wave emissions at electron cyclotron harmonics and at frequencies above the local plasma frequency are commonly observed in different magnetospheric regions. We show that such emissions when observed in the cusp, mantle or polar cap can be generated by shell-type electron distributions. We present an example of observations of such shell type dist…
Comment on ``Interplanetary shocks unconnected with earthbound coronal mass ejections'' by T. A. Howard and S. J. Tappin
Gopalswamy, Nat; Akiyama, Sachiko; Yashiro, Seiji +1 more
Abstract Available from http://www.agu.org
Cluster observations of energetic ionospheric ion beams in the auroral region: Acceleration and associated energy-dispersed precipitation
Rème, H.; Dunlop, M.; Bosqued, J. M. +8 more
This paper presents a detailed study of the Feb. 14, 2001 Cluster northern auroral pass at mid-altitudes (4-5 RE), characterized by observations of a series of energy-dispersed ion structures in a region of poleward convection. In contradiction with one current view, that ions populating these energy-dispersed signatures originate spora…
Fluvial sedimentary deposits on Mars: Ancient deltas in a crater lake in the Nili Fossae region
Head, James W.; Fassett, Caleb I.
New spacecraft observations in the Nili Fossae region of Mars reveal two valley networks (~80 and ~200 km long) that each formed distributary fans as they entered an ancient 40-km diameter impact crater. An outlet channel on the eastern crater rim, lying at an elevation above the fans, suggests these fans formed as subaqueous deltas in a crater la…
The October 28, 2003 extreme EUV solar flare and resultant extreme ionospheric effects: Comparison to other Halloween events and the Bastille Day event
Tsurutani, B. T.; Didkovsky, L.; Judge, D. L. +16 more
Some of the most intense solar flares measured in 0.1 to 0.8 nm x-rays in recent history occurred near the end of 2003. The Nov 4 event is the largest in the NOAA records (X28) and the Oct 28 flare was the fourth most intense (X17). The Oct 29 flare was class X7. These flares are compared and contrasted to the July 14, 2000 Bastille Day (X10) even…
Dimensional analysis of observed structures using multipoint magnetic field measurements: Application to Cluster
Balogh, A.; Zhang, H.; Zong, Q. -G. +6 more
A new method is described to analyze the dimensional character of observed structures using multipoint magnetic field measurements of four or more spacecraft. The technique can provide three directions along which the magnetic field has the minimum, intermediate, and maximum derivatives if the magnetic gradient tensor G = $\nabla$$\vec{B at every …