Search Publications
Modification of the dichotomy boundary on Mars by Amazonian mid-latitude regional glaciation
Head, James W.; Neukum, Gerhard; Marchant, David R. +1 more
Restoration of the dichotomy boundary to its original position to assess its origin requires a thorough knowledge of processes responsible for its degradation and retreat. The unique fretted terrain, located along the Deuteronilus-Protonilus Mensae northern mid-latitude portion of the boundary, has been long held to provide clues to dichotomy degr…
Solar control of radar wave absorption by the Martian ionosphere
Gurnett, D. A.; Morgan, D. D.; Plaut, J. J. +6 more
The MARSIS active sounder aboard the Mars Express spacecraft, under certain conditions in the Martian ionosphere, fails to detect the planetary surface. We have generated a statistical measure of the surface reflection visibility, which we plot as a time series and compare with both in situ particle data taken at Mars and solar x-ray data taken at…
Hydrogen exosphere at Mars: Pickup protons and their acceleration at the bow shock
Barabash, S.; Lundin, R.; Yamauchi, M. +3 more
Pickup protons (PIs) with a ring-beam distribution originating from the extended hydrogen exosphere of Mars are observed by the ASPERA-3 experiment onboard the Mars Express spacecraft at solar minimum conditions. PIs can contribute ~1% to the solar wind number density at close distances to the flank bow shock. The observed fluxes of PIs indicate t…
Dust devils on Mars observed by the High Resolution Stereo Camera
Greeley, Ronald; Pätzold, Martin; Neukum, Gerhard +2 more
Fourteen active dust devils were observed by the High Resolution Stereo Camera (HRSC) on Mars Express, which enable the first analysis of the forward speed of dust devils on Mars determined from orbit. Results show speeds on the order of 20 m/s, which compares favorably with values of the wind profiles estimated from the Martian Climate Database f…
Geologically recent tectonic, volcanic and fluvial activity on the eastern flank of the Olympus Mons volcano, Mars
Head, J. W.; Neukum, G.; van Gasselt, S. +4 more
We show evidence of very recent (<=25-40 Myr) geologic activity on the eastern flank of Olympus Mons volcano that includes a suite of fluvial (channel networks), volcanic (emplacement of lava flows and dikes), and tectonic (wrinkle ridges and troughs) processes. The combination and youth of these features confirms the importance of geological a…
A steep fan at Coprates Catena, Valles Marineris, Mars, as seen by HRSC data
Neukum, G.; Hauber, E.; Reiss, D. +4 more
We investigate a steep fan-like deposit in the Coprates Catena region, using the new High Resolution Stereo Camera (HRSC) data and other Martian data sets. Water flowing in a 45-km-long sapping valley entered a deep trough and formed a stepped fan 1100-m-high above the trough floor with a mean slope of 7.4°. The origin of the fan is uncertain. How…
A structural study of an interior layered deposit in southwestern Candor Chasma, Valles Marineris, Mars, using high resolution stereo camera data from Mars Express
Scholten, F.; Neukum, G.; Hauber, E. +5 more
An interior layered deposit (ILD) within Western Candor Chasma of Valles Marineris, Mars, is examined using data from the High Resolution Stereo Camera of the Mars Express mission. Most ILD layers dip in the same direction as the topographic slope. Exposed, rotated fault blocks of basement lithology appear to penetrate the cover of this ILD deposi…
Mapping sub-pixel surface roughness on Mars using high-resolution satellite image data
Gillespie, Alan R.; Mushkin, Amit
The ratio between co-registered pixels in stereo or repeat image pairs is used to constrain the deviation of the Martian surface from Lambertian reflection due to unresolved shadows at the pixel scale of orbiting imagers. Relative differences between the ratios primarily reflect differences in the effective amount of shadows `seen' by the sensor i…
Reconstructing the weather on Mars at the time of the MERs and Beagle 2 landings
Withers, P.; Lewis, S. R.; Read, P. L. +1 more
We reconstruct the temperature, wind and density structure of the atmosphere on Mars from the surface to 120 km altitude at the time of the landing of the two NASA Mars Exploration Rovers (MER), and ESA's ``Beagle 2.'' This reconstruction is based on an assimilation of temperature and dust opacity observations from the Thermal Emission Spectromete…
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 …