Search Publications
Precipitation Driven Pedogenic Weathering of Volcaniclastics on Early Mars
Michalski, J. R.; Ye, B.
Compositional stratigraphy, generally composed of Al rich clay minerals overlying Fe/Mg rich clay minerals, is observed in many locations on Mars. Here we describe the occurrence of such mineralogical stratigraphy in settings where the protoliths are almost certainly pyroclastic materials. One such example includes altered rocks high on the summit…
Enhanced Super-Rotation Before and During the 2018 Martian Global Dust Storm
Fedorova, Anna A.; Holmes, James A.; Lewis, Stephen R. +3 more
Super-rotation affects—and is affected by—the distribution of dust in the martian atmosphere. We modeled this interaction during the 2018 global dust storm (GDS) of Mars Year 34 using data assimilation. Super-rotation increased by a factor of two at the peak of the GDS, as compared to the same period in the previous year which did not feature a GD…
Caldera Collapse as the Trigger of Chaos and Fractured Craters on the Moon and Mars
Massironi, Matteo; Rossi, Angelo Pio; Pozzobon, Riccardo +3 more
Chaotic terrains are broad regions on Mars characterized by the disruption of the basaltic bedrock into polygonal blocks separated by deep fractures. To date, the proposed genetic scenarios often involve the occurrence of subsurface ice or liquid H2O. Nevertheless, similar features also occur within some craters on the Moon, namely floo…
Global Venus Solar Wind Coupling and Oxygen Ion Escape
Fedorov, A.; Barabash, S.; Futaana, Y. +5 more
The present day Venusian atmosphere is dry, yet, in its earlier history a significant amount of water evidently existed. One important water loss process comes from the energy and momentum transfer from the solar wind to the atmospheric particles. Here, we used measurements from the Ion Mass Analyzer onboard Venus Express to derive a relation betw…
Cassini Observation of Relativistic Electron Butterfly Distributions in Saturn's Inner Radiation Belts: Evidence for Acceleration by Local Processes
Krupp, N.; Wei, Y.; Roussos, E. +3 more
The morphology of electron pitch angle distributions (PADs) helps to identify dynamic processes in Saturn's magnetosphere. Previous studies demonstrated convective transport being important for relativistic electron acceleration at L > 4 in the inner magnetosphere, whereas closer to Saturn the situation is not as well established. We have inves…
First Observation of the Oxygen 630 nm Emission in the Martian Dayglow
Aoki, S.; Vandaele, A. C.; Daerden, F. +13 more
Following the recent detection of the oxygen green line airglow on Mars, we have improved the statistical analysis of the data recorded by the NOMAD/UVIS instrument on board the ExoMars Trace Gas Orbiter mission by summing up hundreds of spectra to increase the signal to noise ratio. This led to the observation of the OI 630 nm emission, the first…
Magnetic Topology at Venus: New Insights Into the Venus Plasma Environment
Xu, Shaosui; Frahm, Rudy A.; Luhmann, Janet G. +2 more
This study provides the first characterization of magnetic topology (i.e., the magnetic connectivity to the collisional ionosphere) at Venus, which might give new insights into the Venusian space environment on topics such as the penetration of the interplanetary magnetic field (IMF) into the ionosphere, planetary ion outflow and inflow, and auror…
Alternatives to Liquid Water Beneath the South Polar Ice Cap of Mars
Steinbrügge, Gregor; Schroeder, Dustin M.
Radar sounding of Mars' south polar ice cap has revealed portions of its base with stronger radar returns than its surface. These have been used to estimate high real permittivity values consistent with liquid water. However, the thermal, chemical, and geological conditions required to sustain such water bodies are challenging to achieve in the co…
Active Boulder Falls in Terra Sirenum, Mars: Constraints on Timing and Causes
Conway, Susan J.; Grindrod, Peter M.; Davis, Joel M. +1 more
We use time series images to identify significant active boulder falls in an impact crater on Mars. Evidence for active boulder falls include boulder trails with impact marks from bouncing and rolling, and dark patches from boulder impacts away from the base of the crater walls. We were able to define three time periods with active boulder falls a…
Jupiter's Double-Arc Aurora as a Signature of Magnetic Reconnection: Simultaneous Observations From HST and Juno
Wei, Y.; Bonfond, B.; Vogt, M. F. +10 more
Jupiter's powerful auroral emission is usually divided into the polar, main, and equatorward components. The driver of Jupiter's main aurora is a central question for the community. Previous investigations reveal many distinct substructures on the main auroral oval, which are indicators of fundamentally different magnetospheric processes. Understa…