Search Publications
Seasonal variability of the hydrogen exosphere of Mars
Halekas, J. S.
The Mars Atmosphere and Volatile EvolutioN (MAVEN) mission measures both the upstream solar wind and collisional products from energetic neutral hydrogen atoms that precipitate into the upper atmosphere after their initial formation by charge exchange with exospheric hydrogen. By computing the ratio between the densities of these populations, we d…
Spectral properties of Martian and other planetary glasses and their detection in remotely sensed data
Mustard, John F.; Dyar, M. Darby; Cannon, Kevin M. +3 more
Thirty silicate glasses were synthesized as realistic analogs to those expected to exist on Mars, the Moon, and Mercury. Samples were measured using visible/near-infrared and Mössbauer spectroscopy to determine the effects of varying bulk chemistry, oxygen fugacity, and temperature on spectral properties. For Martian glasses, the fO2 du…
Winds in the Middle Cloud Deck From the Near-IR Imaging by the Venus Monitoring Camera Onboard Venus Express
Fedorova, A. A.; Ignatiev, N. I.; Markiewicz, W. J. +4 more
For more than 8 years the Venus Monitoring Camera (VMC) onboard the Venus Express orbiter performed continuous imaging of the Venus cloud layer in UV, visible and near-IR filters. We applied the correlation approach to sequences of the near-IR images at 965 nm to track cloud features and determine the wind field in the middle and lower cloud (49-5…
Three-dimensional turbulence-resolving modeling of the Venusian cloud layer and induced gravity waves
Lebonnois, Sébastien; Spiga, Aymeric; Lefèvre, Maxence
The impact of the cloud convective layer of the atmosphere of Venus on the global circulation remains unclear. The recent observations of gravity waves at the top of the cloud by the Venus Express mission provided some answers. These waves are not resolved at the scale of global circulation models (GCM); therefore, we developed an unprecedented 3-…
Vertical structure of the axi-asymmetric temperature disturbance in the Venusian polar atmosphere: Comparison between radio occultation measurements and GCM results
Tellmann, Silvia; Pätzold, Martin; Imamura, Takeshi +6 more
Vertical temperature profiles at 40-75 km around 80°N in the Venus polar vortex are retrieved over 13 Earth days almost continuously from radio occultation measurements (Venus Express radio occultation) in the Venus Express mission. They show periodical variations with a dominant period of ∼3.1 Earth days. These fluctuations are confined in an alt…
Acidic weathering of basalt and basaltic glass: 1. Near-infrared spectra, thermal infrared spectra, and implications for Mars
Christensen, Philip R.; Cloutis, Edward A.; Mann, Paul +2 more
Acid-leached rinds and coatings occur in volcanic environments on Earth and have been identified using orbital spectroscopy on Mars, but their development is poorly understood. We simulated long-term open-system acidic weathering in a laboratory by repeatedly rinsing and submerging crystalline and glassy basalts in pH 1 and pH 3 acidic solutions f…
Radar sounding of Lucus Planum, Mars, by MARSIS
Rossi, Angelo Pio; Orosei, Roberto; Cartacci, Marco +6 more
Lucus Planum, extending for a radius of approximately 500 km around 181°E, 5°S, is part of the Medusae Fossae Formation (MFF), a set of several discontinuous deposits of fine-grained, friable material straddling across the Martian highland-lowland boundary. The MFF has been variously hypothesized to consist of pyroclastic flows, pyroclastic airfal…
Flank vents and graben as indicators of Late Amazonian volcanotectonic activity on Olympus Mons
Christensen, P. R.; Peters, S. I.
Previous studies have focused on large-scale features on Olympus Mons, such as its flank terraces, the summit caldera complex, and the basal escarpment and aureole deposits. Here we identify and characterize previously unrecognized and unmapped small scale features to help further understand the volcanotectonic evolution of this enormous volcano. …
The anatomy of a wrinkle ridge revealed in the wall of Melas Chasma, Mars
Andrews-Hanna, Jeffrey C.; Cole, Hank M.
Wrinkle ridges are among the most common tectonic structures on the terrestrial planets and provide important records of the history of planetary strain and geodynamics. The observed broad arches and superposed narrow wrinkles are thought to be the surface manifestation of blind thrust faults, which terminate in near-surface volcanic sequences and…
Search for active lava flows with VIRTIS on Venus Express
Drossart, P.; Piccioni, G.; Smrekar, S. +3 more
The Visible Infrared Thermal Imaging Spectrometer (VIRTIS) instrument on Venus Express observed thermal emission from the surface of Venus at 1 µm wavelength and thus would have detected sufficiently bright incandescent lava flows. No eruptions were detected in the observations between April 2006 and October 2008, covering an area equivalent…