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Hale crater, a 125×150km impact crater located near the intersection of Uzboi Vallis and the northern rim of Argyre basin at 35.7°S, 323.6°E, is surrounded by channels that radiate from, incise, and transport material within Hale’s ejecta. The spatial and temporal relationship between the channels and Hale’s ejecta strongly suggests the impact event created or modified the channels and emplaced fluidized...
The Moon has long been known to have an overall shape not consistent with expected past tidal forces. It has recently been suggested (Garrick-Bethell, I., Wisdom, J., Zuber, M.T. [2006]. Science 313, 652–655) that the present lunar moments of inertia indicate a past high-eccentricity orbit and, possibly, a past non-synchronous spin–orbit resonance. Here I show that the match between the lunar shape...
We present observations and models that together explain many hallmarks of the structure and growth of small impact craters forming in targets with aligned fractures. Endurance Crater at Meridiani Planum on Mars (diameter≈150m) formed in horizontally-layered aeolian sandstones with a prominent set of wide, orthogonal joints. A structural model of Endurance Crater is assembled and used to estimate...
We present the results of laboratory experiments to study the sediment transport and erosional capacity of water at current martian temperature and pressure. We have performed laboratory simulation experiments in which a stream of water flowed over test beds at low temperature (∼−20°C) and low pressure (∼7mbar). The slope angle was 14° and three sediment types were tested. We compared the erosive...
We provide evidence of consistency between the dynamical evolution of main belt asteroids and their color evolution due to space weathering. The dynamical age of an asteroid’s surface (Bottke, W.F., Durda, D.D., Nesvorný, D., Jedicke, R., Morbidelli, A., Vokrouhlický, D., Levison, H. [2005]. Icarus 175 (1), 111–140; Nesvorný, D., Jedicke, R., Whiteley, R.J., Ivezić, Ž. [2005]. Icarus 173, 132–152)...
In this paper the Stardust disk-integrated phase curve at phase 47.2–134.6° of the Asteroid 5535 Annefrank, combined with groundbased observations (at phase 2.3–18.3°), are fit with Hapke’s photometric model. We confirm Newburn et al.’s (Newburn, R.L. et al. [2003]. J. Geophys. Res. 108 (E11), 5117. doi:10.1029/2003JE002106) observation that Annefrank exhibits a steep phase curve. This manifests itself...
The Amazonian period of Mars has been described as static, cold, and dry. Recent analysis of high-resolution imagery of equatorial and mid-latitude regions has revealed an array of young landforms produced in association with ice and liquid water; because near-surface ice in these regions is currently unstable, these ice-and-water-related landforms suggest one or more episodes of martian climate change...
The search for life beyond the Solar System is a major activity in exoplanet science. However, even if an Earth-like planet were to be found, it is unlikely to be at a similar stage of evolution as the modern Earth. It is therefore of interest to investigate the sensitivity of biomarker signals for life as we know it for an Earth-like planet but at earlier stages of evolution. Here, we assess biomarkers,...
Self-organised patterns of stone stripes, polygons, circles and clastic solifluction lobes form by the sorting of clasts from fine-grained sediments in freeze–thaw cycles. We present new High Resolution Imaging Science Experiment (HiRISE) images of Mars which demonstrate that the slopes of high-latitude craters, including Heimdal crater – just 25km east of the Phoenix Landing Site – are patterned...
We solve numerically the equations describing the transfer of heat through the lithosphere of Io by a mixture of conduction and volcanic advection as proposed by O’Reilly and Davies (O’Reilly, T.C., Davies, G.F. [1981]. Geophys. Res. Lett. 8, 313–316), removing the requirement that average material properties must be used. As expected, the dominance of advective heat transfer by volcanic eruptions...
We report an improved measurement of the rotational axis orientation of Asteroid (4) Vesta. By analyzing and combining all previous measurements using a limb-fitting technique from ground/HST data collected from 1983 to 2006, we derive a pole solution of (RA=304.5°, Dec=41.5°). Images of Vesta acquired with the Wide Field Camera 3 onboard the Hubble Space Telescope (HST) in February 2010 are combined...
We analyze EUV spatially-resolved dayglow spectra obtained at 0.37nm resolution by the UVIS instrument during the Cassini flyby of Venus on 24 June 1999, a period of high solar activity level. Emissions from OI, OII, NI, CI and CII and CO have been identified and their disc average intensity has been determined. They are generally somewhat brighter than those determined from the observations made...
Janus and Epimetheus are famously known for their distinctive horseshoe-shaped orbits resulting from a 1:1 orbital resonance. Every 4 years these two satellites swap their orbits by a few tens of kilometers as a result of their close encounter. Recently Tiscareno et al. (Tiscareno, M.S., Thomas, P.C., Burns, J.A. [2009]. Icarus 204, 254–261) have proposed a model of rotation based on images from the...
New global maps of the five inner midsize icy saturnian satellites, Mimas, Enceladus, Tethys, Dione, and Rhea, have been constructed in three colors (UV, Green and near-IR) at resolutions of 1km/pixel. The maps reveal prominent global patterns common to several of these satellites but also three major color features unique to specific satellites or satellite subgroups. The most common features among...
The Veritas family is located in the outer main belt and is named after its apparent largest constituent, Asteroid (490) Veritas. The family age has been estimated by two independent studies to be quite young, around 8Myr. Therefore, current properties of the family may retain signatures of the catastrophic disruption event that formed the family. In this paper, we report on our investigation of the...
Recent analyses of Galileo magnetometer and gravity data justifies approximations that allow estimates of the magnetic fields generated by Europa’s ocean tides to be made even though some of the ocean parameters that would generally be required are unavailable. We show solutions for the magnetic fields generated by published estimates of ocean tides on Europa and provide simple scaling formulas that...
We use a radiative–conductive model to least-squares fit Pluto stellar occultation light curve data. This model predicts atmospheric temperature based on surface temperature, surface pressure, surface radius, and CH 4 and CO mixing ratios, from which model light curves are to be calculated. The model improves upon previous techniques for deriving Pluto’s atmospheric thermal structure from...
We present results of a series of large-scale experiments to measure the coefficient of restitution for 1-m-diameter rocky bodies in impacts with collision speeds up to ∼1.5ms −1 . The experiments were conducted in an outdoor setting, with two 40-ton cranes used to suspend the ∼1300-kg granite spheres pendulum-style in mutual contact at the bottoms of their respective paths of motion. The...
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