Geology topics

Oded Aharonson

Publications and source records attributed to Oded Aharonson.

5 recordsLinked to original sources

USGS2021

GANGOTRI mission concept on the glacial key to the Amazonian climate of Mars

The GANGOTRI mission concept would investigate in situ the geologic origins of midlatitudinal Martian glaciers, as underlain by Amazonian climate evolution, by riddling the ice with a hybrid thermo-mechanical drill for deep englacial sampling. GANGOTRI would use regolith compositional measurements to characterize ice-regolith interaction, and stable isotope measurements to characterize fundamental exchange processes of major ice reservoirs. Meanwhile, geophysical observations would cross-calibrate composition.

Bulletin of the AAS↗

USGS2017

Preface: The lunar reconnaissance orbiter

When the call for papers for a special issue of Icarus devoted to analysis of data from the Lunar Reconnaissance Orbiter mission was announced in March 2015 we envisioned a single issue with only a possibility of a second. We certainly were gratified by the response from within and outside the LRO instrument teams such that we were compelled to publish this the third and final volume. It is a testament to the Moon as object that enhances our understanding of the history of the Earth-Moon system, the Solar System as a whole, and geologic processes that take place on the Moon and other atmosphere-less bodies. Many of the publications included lead authors outside the LRO team of co-investigators, using data from multiple instruments from LRO and other recent missions.

Icarus↗

USGS2011

Hypsometry of Titan

Cassini RADAR topography data are used to evaluate Titan’s hypsometric profile, and to make comparisons with other planetary bodies. Titan’s hypsogram is unimodal and strikingly narrow compared with the terrestrial planets. To investigate topographic extremes, a novel variant on the classic hypsogram is introduced, with a logarithmic abscissa to highlight mountainous terrain. In such a plot, the top of the terrestrial hypsogram is quite distinct from those of Mars and Venus due to the ‘glacial buzz-saw’ that clips terrestrial topography above the snowline. In contrast to the positive skew seen in other hypsograms, with a long tail of positive relief due to mountains, there is an indication (weak, given the limited data for Titan so far) that the Titan hypsogram appears slightly negatively skewed, suggesting a significant population of unfilled depressions. Limited data permit only a simplistic comparison of Titan topography with other icy satellites but we find that the standard deviation of terrain height (albeit at different scales) is similar to those of Ganymede and Europa.

Icarus↗

USGS2008

Titan's inventory of organic surface materials

Cassini RADAR observations now permit an initial assessment of the inventory of two classes, presumed to be organic, of Titan surface materials: polar lake liquids and equatorial dune sands. Several hundred lakes or seas have been observed, of which dozens are each estimated to contain more hydrocarbon liquid than the entire known oil and gas reserves on Earth. Dark dunes cover some 20% of Titan's surface, and comprise a volume of material several hundred times larger than Earth's coal reserves. Overall, however, the identified surface inventories (>3 × 10 4 km 3 of liquid, and >2 × 10 5 km 3 of dune sands) are small compared with estimated photochemical production on Titan over the age of the solar system. The sand volume is too large to be accounted for simply by erosion in observed river channels or ejecta from observed impact craters. The lakes are adequate in extent to buffer atmospheric methane against photolysis in the short term, but do not contain enough methane to sustain the atmosphere over geologic time. Unless frequent resupply from the interior buffers this greenhouse gas at exactly the right rate, dramatic climate change on Titan is likely in its past, present and future.

Geophysical Research Letters↗

USGS2008

Quasi-periodic bedding in the sedimentary rock record of mars

Widespread sedimentary rocks on Mars preserve evidence of surface conditions different from the modern cold and dry environment, although it is unknown how long conditions favorable to deposition persisted. We used 1-meter stereo topographic maps to demonstrate the presence of rhythmic bedding at several outcrops in the Arabia Terra region. Repeating beds are ∼10 meters thick, and one site contains hundreds of meters of strata bundled into larger units at a ∼10:1 thickness ratio. This repetition likely points to cyclicity in environmental conditions, possibly as a result of astronomical forcing. If deposition were forced by orbital variation, the rocks may have been deposited over tens of millions of years.

Science↗