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NASA’s Phoenix lander identified perchlorate and carbonate salts on Mars. Perchlorates are rare on Earth, and carbonates have largely been ignored on Mars following the discovery by NASA’s Mars Exploration Rovers of acidic precipitated minerals such as jarosite. In light of the Phoenix results, we updated the aqueous thermodynamic model FREZCHEM to include perchlorate chemistry. FREZCHEM models the...
We explore the initial conditions for fragments in the extended regions (r≳50AU) of gravitationally unstable disks. We combine analytic estimates for the fragmentation of spiral arms with 3D SPH simulations to show that initial fragment masses are in the gas giant regime. These initial fragments will have substantial angular momentum, and should form disks with radii of a few AU. We show that clumps...
Motivated by radar and near-infrared data indicating that Titan’s polar lakes are extremely smooth, we consider the conditions under which a lake surface will be ruffled by wind to form capillary waves. We evaluate laboratory data on wind generation and derive, without scaling for surface tension effects, a threshold for pure methane/ethane of ∼0.5–1m/s. However, we compute the physical properties...
The cumulative effects of weak resonant and secular perturbations by the major planets produce chaotic behavior of asteroids on long timescales. Dynamical chaos is the dominant loss mechanism for asteroids with diameters D≳10km in the current asteroid belt. In a numerical analysis of the long-term evolution of test particles in the main asteroid belt region, we find that the dynamical loss history...
Mars General Circulation Model (GCM) simulations are presented to illustrate the importance of the ice emissivity of the seasonal CO 2 polar caps in regulating the effects of airborne dust on the martian CO 2 cycle. Simulated results show that atmospheric dust suppresses CO 2 condensation when the CO 2 ice emissivity is high but enhances it when the CO 2 ice...
Impacts of comets and asteroids play an important role in volatile delivery on the Moon. We use a novel method for tracking vapor masses that reach escape velocity in hydrocode simulations of cometary impacts to explore the effects of volatile retention. We model impacts on the Moon to find the mass of vapor plume gravitationally trapped on the Moon as a function of impact velocity. We apply this...
Scattering and absorption of sunlight by aerosols are integral to understanding the radiative balance of any planetary atmosphere covered in a haze, such as Titan and possibly the early Earth. One key optical parameter of an aerosol is its refractive index. We have simulated both Titan and early Earth organic haze aerosols in the laboratory and measured the real and imaginary portion of their refractive...
The present-day thermal state of the martian interior is a very important issue for understanding the internal evolution of the planet. Here, in order to obtain an improved upper limit for the heat flow at the north polar region, we use the lower limit of the effective elastic thickness of the lithosphere loaded by the north polar cap, crustal heat-producing elements (HPE) abundances based on martian...
Multiple impact basins formed on the Moon about 3.8 Gyr ago in what is known as the lunar cataclysm or Late Heavy Bombardment. Many workers currently interpret the lunar cataclysm as an impact spike primarily caused by main-belt asteroids destabilized by delayed planetary migration. We show that morphologically fresh (class 1) craters on the lunar highlands were mostly formed during the brief tail...
Up to now, there has been no corroboration from Cassini CIRS of the Voyager IRIS-discovery of cyanoacetylene (HC 3 N) ice in Titan’s thermal infrared spectrum. We report the first compelling spectral evidence from CIRS for the ν 6 HC 3 N ice feature at 506cm −1 at latitudes 62°N and 70°N, from which we derive particle sizes and column abundances in Titan’s lower stratosphere...
The present paper deals with the application of the classical theory of equilibrium figures of two rotating liquid masses to the case where bodies exhibit a radially stratified internal density distribution so that they can be considered as inhomogeneous bodies. The derived ellipsoidal shape solutions are applied to five real systems of equal-sized synchronous asteroids. Furthermore, internal inhomogeneity...
Martian valley networks provide the best evidence that the climate on Mars was different in the past. Although these features are located primarily in heavily cratered terrain of Noachian age (>3.7Ga), the ages of the features and the time when they were active is not well understood. From superposed craters several recent global studies determined that most valley networks formed during the Late...
The Cassini mission revealed two spectacular characteristics of Iapetus: (1) a geologically old and high equatorial ridge, which is unique in the Solar System and (2) a large flattening of 35km consistent with the equilibrium figure for a hydrostatic body rotating with a period of 16h, whereas the current spin period is 79.33 days. This study describes three-dimensional simulations of solid-state...
We produced regional geologic maps of the Hi’iaka and Shamshu regions of Io’s antijovian hemisphere using Galileo mission data to assess the geologic processes that are involved in the formation of Io’s mountains and volcanic centers. Observations reveal that these regions are characterized by several types of volcanic activity and features whose orientation and texture indicate tectonic activity...
We have observed well-sampled phase curves for nine Trojan asteroids in B-, V-, and I-bands. These were constructed from 778 magnitudes taken with the 1.3-m telescope on Cerro Tololo as operated by a service observer for the SMARTS consortium. Over our typical phase range of 0.2–10°, we find our phase curves to be adequately described by a linear model, for slopes of 0.04–0.09mag/° with average uncertainty...
In the lower troposphere of the Titan the temperature is about 90K, therefore the chemical production of compounds in the CH 4 /N 2 atmosphere is extremely slow. However, atmospheric electricity could provide conditions at which chemical reactions are fast. This paper is based on the assumption that there are lightning discharges in the Titan’s lower atmosphere. The temporal temperature...
It is shown that viscous liquid film flow (VLF-flow) on the surfaces of slopes of martian dunes can be a low-temperature rheological phenomenon active today on high latitudes. A quantitative model indicates that the VLF-flows are consistent with the flow of liquid brines similar to that observed by imaging at the Phoenix landing site. VLF-flows depend on the viscosity, dynamics, and energetics of...
We have compiled a global geological map of Ganymede that represents the most recent understanding of the satellite based on Galileo mission results. This contribution builds on important previous accomplishments in the study of Ganymede utilizing Voyager data and incorporates the many new discoveries that were brought about by examination of Galileo data. We discuss the material properties of geological...
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