Search Publications
Stratigraphy in the Mawrth Vallis region through OMEGA, HRSC color imagery and DTM
Mangold, N.; Bibring, J. -P.; Gondet, B. +7 more
The Mawrth Vallis region contains an extensive (at least 300 km × 400 km) and thick (⩾300 m), finely layered (at meter scale), clay-rich unit detected by OMEGA. We use OMEGA, HRSC DTMs derived from stereoscopic imagery, HRSC color imagery and high resolution imagery such as MOC, CTX and HiRISE to characterize the geometry and the composition of th…
Stability of methane clathrate hydrates under pressure: Influence on outgassing processes of methane on Titan
Sotin, Christophe; Choukroun, Mathieu; Tobie, Gabriel +1 more
We have conducted high-pressure experiments in the H 2O-CH 4 and H 2O-CH 4-NH 3 systems in order to investigate the stability of methane clathrate hydrates, with an optical sapphire-anvil cell coupled to a Raman spectrometer for sample characterization. The results obtained confirm that three …
Concentric crater fill in the northern mid-latitudes of Mars: Formation processes and relationships to similar landforms of glacial origin
Head, James W.; Marchant, David R.; Levy, Joseph
Hypotheses accounting for the formation of concentric crater fill (CCF) on Mars range from ice-free processes (e.g., aeolian fill), to ice-assisted talus creep, to debris-covered glaciers. Based on analysis of new CTX and HiRISE data, we find that concentric crater fill (CCF) is a significant component of Amazonian-aged glacial landsystems on Mars…
Color imaging of Mars by the High Resolution Imaging Science Experiment (HiRISE)
Tornabene, Livio L.; Bridges, Nathan T.; Thomas, Nicolas +13 more
HiRISE has been producing a large number of scientifically useful color products of Mars and other planetary objects. The three broad spectral bands, coupled with the highly sensitive 14 bit detectors and time delay integration, enable detection of subtle color differences. The very high spatial resolution of HiRISE can augment the mineralogic int…
Distribution and interplay of geologic processes on Titan from Cassini radar data
Stiles, B.; Callahan, P.; Cassini RADAR Team +23 more
The Cassini Titan Radar Mapper is providing an unprecedented view of Titan's surface geology. Here we use Synthetic Aperture Radar (SAR) image swaths (Ta-T30) obtained from October 2004 to December 2007 to infer the geologic processes that have shaped Titan's surface. These SAR swaths cover about 20% of the surface, at a spatial resolution ranging…
The age of the Medusae Fossae Formation: Evidence of Hesperian emplacement from crater morphology, stratigraphy, and ancient lava contacts
Head, James W.; Kerber, Laura
The Medusae Fossae Formation (MFF), covering about 2.1 × 10 6 km 2 (with an estimated volume of 1.4 × 10 6 km 3) and straddling the equatorial region of Mars east of Tharsis, has historically been mapped and dated as Amazonian in age. Analysis of the MFF using a range of new observations from recent miss…
Collisional spreading of Enceladus’ neutral cloud
Johnson, R. E.; Cassidy, T. A.
We describe a direct simulation Monte Carlo (DSMC) model of Enceladus' neutral cloud and compare its results to observations of OH and O orbiting Saturn. The OH and O are observed far from Enceladus (at 3.95 R S), as far out as 25 R S for O. Previous DSMC models attributed this breadth primarily to ion/neutral scattering (inc…
Shell thickness variations and the long-wavelength topography of Titan
Nimmo, F.; Bills, B. G.
The long-wavelength topography of Titan has an amplitude larger than that expected from tidal and rotational distortions at its current distance from Saturn. This topography is associated with small gravity anomalies, indicating a high degree of compensation. Both observations can be explained if Titan has a floating, isostatically-compensated ice…
Carbon dioxide on the satellites of Saturn: Results from the Cassini VIMS investigation and revisions to the VIMS wavelength scale
Nicholson, Philip D.; Baines, Kevin H.; Buratti, Bonnie J. +15 more
Several of the icy satellites of Saturn show the spectroscopic signature of the asymmetric stretching mode of C-O in carbon dioxide (CO 2) at or near the nominal solid-phase laboratory wavelength of 4.2675 µm (2343.3 cm -1), discovered with the Visible-Infrared Mapping Spectrometer (VIMS) on the Cassini spacecraft. We r…
Supraglacial and proglacial valleys on Amazonian Mars
Head, James W.; Fassett, Caleb I.; Levy, Joseph S. +2 more
Abundant evidence exists for glaciation being an important geomorphic process in the mid-latitude regions of both hemispheres of Mars, as well as in specific environments at near-equatorial latitudes, such as along the western flanks of the major Tharsis volcanoes. Detailed analyses of glacial landforms (lobate-debris aprons, lineated valley fill,…