The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
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...
The near nucleus coma of Comet 9P/Tempel 1 has been simulated with the 3D Direct Simulation Monte Carlo (DSMC) code PDSC ++ (Su, C.-C. [2013]. Parallel Direct Simulation Monte Carlo (DSMC) Methods for Modeling Rarefied Gas Dynamics. PhD Thesis, National Chiao Tung University, Taiwan) and the derived column densities have been compared to observations of the water vapour distribution found...
Comets are expected to be the most primitive objects in the Solar System. The chemical composition of these objects is frequently assumed to be directly provided by the observations of the abundances of volatile molecules in the coma. The present work aims to determine the relationship between the chemical composition of the coma, the outgassing profile of volatile molecules and the internal chemical...
A thermophysical model is presented that considers surface roughness, cast shadows, multiple or single scattering of radiation, visual and thermal infrared self heating, as well as heat conduction in one or three dimensions. The code is suitable for calculating infrared spectral energy distributions for spatially resolved or unresolved minor Solar System bodies without significant atmospheres or sublimation,...
We present recent observations of main-belt comet P/2010 R2 (La Sagra) obtained using the Gemini North telescope on five nights in late 2011 and early 2013 during portions of the object’s orbit when dust emission was expected to be minimal or absent. We find that P/La Sagra continues to exhibit a faint dust trail aligned with its orbit plane as late as 2011 December 31, while no activity is observed...
I show that the size-distribution of small scattered-disk trans-neptunian objects when derived from the observed size-distribution of Jupiter Family comets (JFCs) and other observational constraints implies that a large percentage (94–97%) of newly arrived active comets within a range of 0.2–15.4km effective radius must physically disrupt, i.e., macroscopically disintegrate, within their median dynamical...
Comet 9P/Tempel 1 was imaged during two consecutive perihelion passages. According to Thomas et al. (Thomas, et al. [2013]. Icarus 222, 453–466) one scarp located at 40°S receded up to 50m. I attempted to use this observation to constrain local material properties of the nucleus. For this purpose I simulated recession of a model scarp due to sub-dust sublimation of ice. I have found, that the observed...
Spacecraft observations of atmosphereless Solar System bodies, combined with thermophysical modeling, provide important information about the thermal inertia and degree of surface roughness of these bodies. The thermophysical models rely on various methods of generating topography, the most common being the concave spherical segment. We here compare the properties of thermal emission for a number...
On 29 November 2011 UT, 2060 Chiron occulted a R=14.9-mag star; data were successfully obtained at the 3-m NASA Infrared Telescope Facility (IRTF) on Mauna Kea and 2-m Las Cumbres Observatory Global Telescope Network (LCOGT) Faulkes Telescope North (FTN) at Haleakala. The MORIS lightcurve shows a solid-body detection of Chiron’s nucleus with a chord duration of 16.0±1.4s, corresponding to a chord...
Previously proposed mechanisms have difficulty explaining the disruption of Comet C/2012 S1 (ISON) as it approached the Sun. We describe a novel cometary disruption mechanism whereby comet nuclei fragment and disperse through dynamic sublimation pressure, which induces differential stresses within the interior of the nucleus. When these differential stresses exceed its material strength, the nucleus...
We present a new analysis of Spitzer observations of Comet 29P/Schwassmann–Wachmann 1 taken on UT 2003 November 21, 23, and 24, similar to a previous investigation of the observations (Stansberry et al., 2004), but using the most recent Spitzer data pipeline products and intensive image processing techniques. Analysis of images from the IRAC 5.8 and 8.0μm bands and the MIPS 24.0 and 70.0μm bands resulted...
From the operation of the MUPUS thermal probe Spohn et al. (2015) concluded that the material of the nucleus of 67P/Churyumov–Gerasimenko is likely to have a high strength, at least locally at the Philae landing site. In this work we consider the derived strength of the material in order to constrain its granulation. For this purpose we performed numerical simulations of the long-term sintering of...
The D/H composition of volatile molecules composing cometary ices brings key constraints on the origin of comets, on the extent of their presolar heritage, as well as on the origin of atmospheres and hydrospheres of terrestrial planets. Nevertheless, the D/H composition may have been modified to various extents in the nucleus when a comet approaches the Sun and experiences deep physical and chemical...
It is speculated that some weakly active comets may be transitional objects between active and dormant comets. These objects are at a unique stage of the evolution of cometary nuclei, as they are still identifiable as active comets, in contrast to inactive comets that are observationally indistinguishable from low albedo asteroids. In this paper, we present a synthesis of comet and meteor observations...
Sublimating gas molecules scatter off of the surface of an icy body in the same manner as photons (Lambertian Scattering). This means that for every photon-driven body force, there should be a sublimation-driven analog that affects icy bodies. Thermal photons emitted from the surfaces of asymmetrically shaped bodies in the Solar System generate net torques that change the spin rates of these bodies...
Sublimation, the direct transition from solid to gas phase, is a process responsible for shaping and changing the reflectance properties of many Solar System surfaces. In this study, we have characterized the evolution of the structure/texture and of the visible and near-infrared (VIS–NIR) spectral reflectance of surfaces made of water ice mixed with analogues of complex extraterrestrial organic matter,...
The surfaces of many objects in the Solar System comprise substantial quantities of water ice sometimes mixed with minerals and/or organic molecules. The sublimation of the ice changes the structural and optical properties of these objects. We present laboratory data on the evolution of the structure and the visible and near-infrared spectral reflectance of icy surface analogues of cometary ices,...
Comet 103P/Hartley 2 has diurnally controlled, CO2-driven activity on the tip of the small lobe of its bilobate nucleus. Such activity is unique among the comet nuclei visited by spacecraft, and suggests that CO2 ice is very near the surface, which is inconsistent with our expectations of an object that thermophysically evolved for ∼45 million years prior to entering the Jupiter Family of comets....
This paper is a continuation of Miles et al. (2015) [Icarus] and Miles (2015b) [Icarus], which detail new observations of Comet 29P/Schwassmann‒Wachmann, characterise its rotational period (∼57d), and identify the presence of discrete sources of outburst on its nucleus: the latter ruling out amorphous-to-crystalline H2O ice transitions as the cause of its outbursts. Summary data are presented for...
From August to November 2014 the Rosetta orbiter has performed an extensive observation campaign aimed at the characterization of 67P/CG nucleus properties and to the selection of the Philae landing site. The campaign led to the production of a global map of the illuminated portion of 67P/CG nucleus. During this prelanding phase the comet’s heliocentric distance decreased from 3.62 to 2.93 AU while...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.