Search Publications
Geochemical Consequences of Widespread Clay Mineral Formation in Mars' Ancient Crust
Ehlmann, Bethany L.; Mangold, Nicolas; Chassefière, Eric +7 more
Clays form on Earth by near-surface weathering, precipitation in water bodies within basins, hydrothermal alteration (volcanic- or impact-induced), diagenesis, metamorphism, and magmatic precipitation. Diverse clay minerals have been detected from orbital investigation of terrains on Mars and are globally distributed, indicating geographically wid…
Quantitative Assessments of the Martian Hydrosphere
Mangold, Nicolas; Mousis, Olivier; Hauber, Ernst +6 more
In this paper, we review current estimates of the global water inventory of Mars, potential loss mechanisms, the thermophysical characteristics of the different reservoirs that water may be currently stored in, and assess how the planet's hydrosphere and cryosphere evolved with time. First, we summarize the water inventory quantified from geologic…
Kinetic Structure of Current Sheets in the Earth Magnetotail
Zelenyi, Lev; Artemyev, Anton
In this paper we present a short review of kinetic models of the thin current sheet and corresponding Cluster observations in the Earth magnetotail. We concentrate mainly on manifestations of non-fluid ion kinetic effects. We discuss the different approaches to model description of the proton component and show that current sheets observed by Clus…
Cosmic Rays in the Inner Heliosphere: Insights from Observations, Theory and Models
Potgieter, M. S.
The global modulation of galactic cosmic rays in the inner heliosphere is determined by four major mechanisms: convection, diffusion, particle drifts (gradient, curvature and current sheet drifts), and adiabatic energy losses. When these processes combine to produce modulation, the complexity increases significantly especially when one wants to de…
Solar Drivers of 11-yr and Long-Term Cosmic Ray Modulation
Richardson, I. G.; Ling, A. G.; Cliver, E. W.
In the current paradigm for the modulation of galactic cosmic rays (GCRs), diffusion is taken to be the dominant process during solar maxima while drift dominates at minima. Observations during the recent solar minimum challenge the pre-eminence of drift at such times. In 2009, the ∼2 GV GCR intensity measured by the Newark neutron monitor increas…
Methods for Characterising Microphysical Processes in Plasmas
Alexandrova, O.; Dudok de Wit, T.; Sorriso-Valvo, L. +2 more
Advanced spectral and statistical data analysis techniques have greatly contributed to shaping our understanding of microphysical processes in plasmas. We review some of the main techniques that allow for characterising fluctuation phenomena in geospace and in laboratory plasma observations. Special emphasis is given to the commonalities between d…
Microphysics of Quasi-parallel Shocks in Collisionless Plasmas
Scholer, M.; Burgess, D.
Shocks in collisionless plasmas require dissipation mechanisms which couple fields and particles at scales much less than the conventional collisional mean free path. For quasi-parallel geometries, where the upstream magnetic field makes a small angle to the shock normal direction, wave-particle coupling produces a broad transition zone with large…
Solar Surface and Atmospheric Dynamics. The Photosphere
Martínez Pillet, V.
Various aspects of the magnetism of the quiet sun are reviewed. The suggestion that a small scale dynamo acting at granular scales generates what we call the quiet sun fields is studied in some detail. Although dynamo action has been proved numerically, it is argued that current simulations are still far from achieving the complexity that might be…
Solar Wind Conditions and Composition During the Genesis Mission as Measured by in situ Spacecraft
Neugebauer, Marcia; Wiens, Roger C.; Zurbuchen, Thomas H. +4 more
We describe the Genesis mission solar-wind sample collection period and the solar wind conditions at the L1 point during this 2.3-year period. In order to relate the solar wind samples to solar composition, the conditions under which the samples were collected must be understood in the context of the long-term solar wind. We find that the state of…
Cosmic Rays Through the Solar Hale Cycle. Insights from Ulysses
Heber, B.
The Ulysses spacecraft had been the first to orbit the Sun over its poles and to explore the heliosphere at these high heliolatitudes. It has now completed three fast latitude scans, two at solar minimum and one at solar maximum. Since its launch in October 1990, this mission has led to several surprising discoveries concerning energetic particles…