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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 100m in diameter and 11–17m deep. Opportunity performed detailed analyses on several ejecta blocks and completed an extensive imaging campaign around the crater. Many of the...
The identification of impact craters on planetary surfaces provides important information about their geological history. Most studies have relied on individual analysts who map and identify craters and interpret crater statistics. However, little work has been done to determine how the counts vary as a function of technique, terrain, or between researchers. Furthermore, several novel internet-based...
We report on the implications of the observations of the glory phenomenon made recently by Venus Express orbiter. Glory is an optical phenomenon that poses stringent constraints on the cloud properties. These observations thus enable us to constrain two properties of the particles at the cloud tops (about 70km altitude) which are responsible for a large fraction of the solar energy absorbed by Venus...
CO 2 clathrate hydrate is a crystalline material composed of water cages around a CO 2 molecule. CO 2 gas hydrates are naturally occurring on Earth and are a likely phase on Mars as well as other cold planetary bodies. CO 2 hydrates have minor effects on terrestrial atmospheric composition, but may be a major reservoir for greenhouse gases on Mars. In this study, CO...
Iron-bearing minerals are a major component of planetary surfaces, and many can be identified by their characteristic absorption bands in the near-infrared (NIR). Here we present laboratory NIR spectra of a wide range of common Fe-bearing minerals (e.g., olivines, pyroxenes), glasses, and mineral/glass mixtures. We then use this suite of spectra to evaluate the effects of mixtures on mineral detection...
Rhea is the second largest icy satellites of Saturn and it is mainly composed of water ice. Its surface is characterized by a leading hemisphere slightly brighter than the trailing side. The main goal of this work is to identify homogeneous compositional units on Rhea by applying the Spectral Angle Mapper (SAM) classification technique to Rhea’s hyperspectral images acquired by the Visual and Infrared...
The aeolian events are frequent on Mars. However, we have very limited understanding of aeolian process, because we cannot conduct experiments, as we did on Earth, on martian surface directly right now. In this paper, we studied the lift-off parameters of saltating particles in wind-blown sand on Mars systematically through a numerical way. The main findings are shown as follows: (1) the lift-off...
Based upon observational evidence and the derived shape-models from seven small Solar System bodies (Comets 103P Hartley 2 and 9P Tempel 1; Asteroids 433 Eros, 243 Ida, 951 Gaspra, and 25143 Itokawa; and the martian moon Phobos) we explore the existence of a self-correcting (negative-feedback) system in which disturbance-triggered downslope regolith flow is constantly working to erode the local surface...
We have modeled an electron precipitation pattern expected on Mimas, Tethys, and Dione, using two different approaches. In the first approach, we adapt a previously developed model to compute an integrated energy flux into the surfaces of Mimas, Tethys, and Dione. This is a guiding-center, bounce-averaged model. In the second approach, we track individual particles in an electromagnetic field for...
Following our recent communication (Gudipati, M.S. et al. [2013]. Nat. Commun. 4, 1648. http://dx.doi.org/10.1038/ncomms2649) on the discovery of condensed-phase non-volatile polymeric material with similar spectral features as tholins, we present here a comprehensive spectroscopic study of photochemical formation of polymeric material from condensed dicyanoacetylene (C 4 N 2 ) ice...
Near-Earth Asteroids (NEAs) have garnered ever increasing attention over the past few years due to the insights they offer into Solar System formation and evolution, the potential hazard they pose, and their accessibility for both robotic and human spaceflight missions. Among the NEAs, carbonaceous asteroids hold particular interest because they may contain clues to how the Earth got its supplies...
The classification criterion between asteroids and comets has evolved in recent decades, but the main distinction remains unchanged. Comets present gas and dust ejection from the surface at some point of their orbits, therefore, these objects are considered to be active. On the other hand, asteroids do not show any kind of large scale gas and dust ejection, they are inert. Nevertheless, this classification...
Some wave features found in the C-ring of Saturn appear to be excited by resonances with normal mode oscillations of the planet. The waves are found at locations in the rings where the ratio of orbital to oscillation frequencies is given by m:m+1 where m is a small integer. I suggest here that it is plausible that ring waves may also be launched at second order resonances where the frequency ratio...
The NASA Dawn spacecraft acquired thousands of images of asteroid Vesta during its year-long orbital tour, and is now on its way to asteroid Ceres. A method for calibrating images acquired by the onboard Framing Camera was described by Schröder et al. (Schröder et al. [2013]. Icarus 226, 1304). However, their method is only valid for point sources. In this paper we extend the calibration to images...
This study reports two sets of dehydration experiments conducted on crystalline alunogen Al 2 (SO 4 ) 3 ·17H 2 O and melanterite FeSO 4 ·7H 2 O under Mars relevant pressure (P) and partial H 2 O pressure (P H2O ) at three temperatures (T). These experimental data are compared with those obtained from a similar set of experiments on crystalline...
A recent debate as to whether plate tectonics should occur on super-Earths raises two questions: (1) how can this disagreement between previous models be disentangled, and (2) what controls the propensity of plate tectonics on Earth and other planets?To tackle these questions, we use a 1D thermal evolution model to study the ratio of driving to resistive forces of plate tectonics for a variety of...
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