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Unexpected variability of Martian hydrogen escape

Montmessin, Franck; Bertaux, Jean-Loup; Chaffin, Michael S. +3 more

Mars today is much drier than the Earth, though they likely began with similar relative amounts of water. One potential cause for this discrepancy is hydrogen loss to space, which may have removed a large fraction of Mars' initial water. Here we demonstrate an order-of-magnitude change in the Martian hydrogen escape rate in 2007, inconsistent with…

Enhanced ionization of the Martian nightside ionosphere during solar energetic particle events

Gurnett, D. A.; Futaana, Y.; Němec, F. +2 more

Electron densities in the Martian nightside ionosphere are more than 90% of time too low to be detected by the Mars Advanced Radar for Subsurface and Ionosphere Sounding radar sounder on board the Mars Express spacecraft. However, the relative number of ionograms with peak electron density high enough to be detected represents a good statistical p…

Fresh exposures of hydrous Fe-bearing amorphous silicates on Mars

Weitz, Catherine M.; Bishop, Janice L.; Baker, Leslie L. +1 more

We have discovered relatively fresh exposures of a hydrated, amorphous material along the wall rock slopes in Coprates Chasma, Mars. Visible and near-infrared reflectance spectra extracted from the deposits exhibit broad absorptions around 1.42, 1.94, and 2.25 µm that are most consistent with laboratory spectra of nanophase hydrated Fe-rich alloph…

Discrepancy between ionopause and photoelectron boundary determined from Mars Express measurements

Barabash, S.; Wei, Y.; Andrews, D. J. +9 more

The Martian ionosphere directly interacts with the solar wind due to lack of a significant intrinsic magnetic field, and an interface is formed in between. The interface is usually recognized by two kinds of indicators: the ionopause identified from ionospheric density profiles and the photoelectron boundary (PEB) determined from the electron ener…

Thermal alteration: A possible reason for the inconsistency between OMEGA/CRISM and TES detections of phyllosilicates on Mars?

Glotch, Timothy D.; Che, Congcong

Previous laboratory analyses have shown that high temperatures can modify the crystal structures of some phyllosilicates in such a way that their spectroscopic signatures appear different from various wavelength perspectives. This may be the case in the Nili Fossae region of Mars, where our analyses indicate that thermally altered (~400°C) Fe-rich…

Dayside episodic ion outflow from Martian magnetic cusps and/or magnetosheath boundary motion associated with plasma oscillations

Gurnett, D. A.; Lundin, R.; Winningham, J. D. +4 more

The radar sounder on the Mars Express Spacecraft is able to make measurements of electron densities in the Martian ionosphere from both local electron plasma oscillations and remote soundings. A study of thousands of orbits shows that in some cases the electron plasma oscillations disappear and reappear abruptly near the upper boundary of the days…