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Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) after nine years of operation: A summary
Gurnett, D. A.; Morgan, D. D.; Orosei, R. +13 more
Mars Express, the first European interplanetary mission, carries the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) to search for ice and water in the Martian subsurface. Developed by an Italian-US team, MARSIS transmits low-frequency, wide-band radio pulses penetrating below the surface and reflected by dielectric discontinui…
Seasonal variation of Martian pick-up ions: Evidence of breathing exosphere
Fedorov, A.; Barabash, S.; Lundin, R. +8 more
The Mars Express (MEX) Ion Mass Analyser (IMA) found that the detection rate of the ring-like distribution of protons in the solar wind outside of the bow shock to be quite different between Mars orbital summer (around perihelion) and orbital winter (around aphelion) for four Martian years, while the north-south asymmetry is much smaller than the …
Comparative pick-up ion distributions at Mars and Venus: Consequences for atmospheric deposition and escape
Luhmann, Janet; Curry, Shannon M.; Hara, Takuya +3 more
Without the shielding of a substantial intrinsic dipole magnetic field, the atmospheres of Mars and Venus are particularly susceptible to similar atmospheric ion energization and scavenging processes. However, each planet has different attributes and external conditions controlling its high altitude planetary ion spatial and energy distributions. …
Late Noachian fluvial erosion on Mars: Cumulative water volumes required to carve the valley networks and grain size of bed-sediment
Rosenberg, Eliott N.; Head, James W., III
Our goal is to quantify the cumulative water volume that was required to carve the Late Noachian valley networks on Mars. We employ an improved methodology in which fluid/sediment flux ratios are based on empirical data, not assumed. We use a large quantity of data from terrestrial rivers to assess the variability of actual fluid/sediment flux sed…
Cold ion escape from the Martian ionosphere
Fedorov, A.; Barabash, S.; Fränz, M. +3 more
We here report on new measurements of the escape flux of oxygen ions from Mars by combining the observations of the ASPERA-3 and MARSIS experiments on board the European Mars Express spacecraft. We show that in previous estimates of the total heavy ion escape flow the contribution of the cold ionospheric outflow with energies below 10 eV has been …
Groove formation on Phobos: Testing the Stickney ejecta emplacement model for a subset of the groove population
Head, James W.; Wilson, Lionel
Numerous theories have been proposed for the formation of grooves on Phobos, and no single explanation is likely to account fully for the wide variety of observed groove morphologies and orientations. One set of grooves is geographically associated with the impact crater Stickney. We test the hypothesis that these grooves were formed by clasts tha…
Estimating precipitation on early Mars using a radiative-convective model of the atmosphere and comparison with inferred runoff from geomorphology
Rauer, H.; Jaumann, R.; Tirsch, D. +5 more
We compare estimates of atmospheric precipitation during the Martian Noachian-Hesperian boundary 3.8 Gyr ago as calculated in a radiative-convective column model of the atmosphere with runoff values estimated from a geomorphological analysis of dendritic valley network discharge rates. In the atmospheric model, we assume CO2-H2
Quantifying geological processes on Mars-Results of the high resolution stereo camera (HRSC) on Mars express
Mangold, N.; Jaumann, R.; Scholten, F. +35 more
This review summarizes the use of High Resolution Stereo Camera (HRSC) data as an instrumental tool and its application in the analysis of geological processes and landforms on Mars during the last 10 years of operation. High-resolution digital elevations models on a local to regional scale are the unique strength of the HRSC instrument. The analy…
Distant ionospheric photoelectron energy peak observations at Venus
Coates, A. J.; Fedorov, A.; Barabash, S. +4 more
The dayside of the Venus ionosphere at the top of the planet's thick atmosphere is sustained by photoionization. The consequent photoelectrons may be identified by specific peaks in the energy spectrum at 20-30 eV which are mainly due to atomic oxygen photoionization. The ASPERA-4 electron spectrometer has an energy resolution designed to identify…
Remnant buried ice in the equatorial regions of Mars: Morphological indicators associated with the Arsia Mons tropical mountain glacier deposits
Head, James W.; Marchant, David R.; Scanlon, Kathleen E.
The fan-shaped deposit (FSD) on the western and northwestern flanks of Arsia Mons is the remnant of tropical mountain glaciers, deposited several tens to hundreds of millions of years ago during periods of high spin-axis obliquity. Previous workers have argued that the Smooth Facies in the FSD contains a core of ancient glacial ice. Here, we find …