km in diameter. Although its orientation is roughly radial to Orientale, its morphology and setting imply that it may not be a secondary crater chain Crater chains, presumably formed by weak asteroids or com(Melosh and Whitaker 1994; Wichman and Wood 1995; Schenk et al. ets stretched apart by planetary tides, have been tentatively 1996). A second is the Abulfeda chain, which is *3.8 Gyr old, is...

En route to Endeavour crater, the Mars Exploration Rover Opportunity embarked on a short but significant campaign at Santa Maria crater during sols 2450–2551. Santa Maria crater is a relatively young impact crater, approximately 100 m in diameter and 11–17 m deep. Opportunity performed detailed analyses on several ejecta blocks and completed an extensive imaging campaign around the crater. Many...

[1] A fresh, 1.85 km diameter impact crater in the midlatitudes of Mars (38°N) named Vaduz exhibits distinctive crater‐related geological subunits (facies) extending up to ∼15 radii from the rim crest and perched >10 m above the adjacent plains. Knobby terrain fringing and underlying the facies is interpreted as degraded thermal contraction crack polygons, consistent with an ice‐rich mantle bur...

[1] On 3 April 2001, a 20 kg point source of fluorescein dye was released 30 m above the bottom of the active summit caldera of Vailulu’u submarine volcano, Samoa. Vailulu’u crater is 2000 m wide and at water depths of 600–1000 m, with the bottom 200 m completely enclosed; it thus provides an ideal site to study the hydrodynamics of an active hydrothermal system. The magmatically driven hydroth...

The recent (14 July 2015) flyby of NASA’s New Horizons spacecraft of the dwarf planet Pluto resulted in the first high-resolution images of the geological surfacefeatures of Pluto. Since previous studies showed that the impact crater size-frequency distribution (SFD) of different celestial objects of our solar system follows power-laws, the aim of the present analysis was to determine, for the ...

The formation and structure of the Orientale basin on the Moon has been extensively studied in the past; however, estimates of its transient crater size, excavated volume and depth, and ejecta distribution remain uncertain. Here we present a new numerical model to reinvestigate the formation and structure of Orientale basin and better constrain impact parameters such as impactor size and veloci...

Using the cometary nucleus model developed by Espinasse et al. (1991), we calculate the thermodynamical evolution of Comet 9P/Tempel 1 over a period of 360 years. Starting from an initially amorphous cometary nucleus which incorporates an icy mixture of H2O and CO, we show that, at the time of Deep Impact collision, the crater is expected to form at depths where ice is in its crystalline form. ...

Introduction: Analyzing the present day morphology in the north polar region of Mars plays an important role in a better understanding of the climatic fluctuation forced by orbital changes and the paleoclimatic chatracteristics of the planet. Based on theoretical computations and observational evidences, the latitudinal distribution of H2O ice on Mars changes according to the orbital changes on...

Introduction: The observed morphologies of impact basins can only be explained by invoking dramatic weakening of the crater walls and floor during crater collapse, but the mechanism underlying the drop in strength is unknown. Here, we explore the possibility that strain-weakening along faults is the primary mechanism. We present a model of temperatureand pressure-dependant strain-weakening alon...

Introduction: Martian paleolakes have been offered as landing sites for in situ and sample-return missions because of their high probability of containing climatic and hydrologic records and potential biomarkers. Prospective paleolake sites are identified in closed craters primarily based on discrepancies between the craters' expected and measured depths and interpretation of associated fluvial...