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Ultraviolet spectral reflectance properties (200–400 nm) of a large number of minerals known or presumed to exist on the surfaces of Mars, the Moon, and asteroids, and in many meteorites, were investigated. Ultraviolet reflectance spectra (200–400 nm) of these minerals range from slightly blue-sloped (reflectance decreasing toward longer wavelengths) to strongly red-sloped (reflectance increasing...
A total of 205 dust devils were detected in 23 High Resolution Stereo Camera (HRSC) images taken between January 2004 and July 2006 with the ESA Mars Express orbiter, in which average dust devil heights were ∼660 m and average diameters were ∼230 m. For the first time, dust devil velocities were directly measured from orbit, and range from 1 to 59 m/s. The observed dust devil directions of motion...
We present the secular light curve of Comet 2P/Encke in two phase spaces, the log plot, and the time plot. The main conclusions of this work are: (a) The comet shows activity at perihelion and aphelion, caused by two different active areas: Source 1, close to the south pole, active at perihelion, and Source 2, at the north pole, centered at aphelion. (b) More than 18 physical parameters are measured...
We estimate the impact flux and cratering rate as a function of latitude on the terrestrial planets using a model distribution of planet crossing asteroids and comets [Bottke, W.F., Morbidelli, A., Jedicke, R., Petit, J.-M., Levison, H.F., Michel, P., Metcalfe, T.S., 2002. Icarus 156, 399–433]. After determining the planetary impact probabilities as a function of the relative encounter velocity and...
The origin of three-dimensional shapes of chondrules is an important information to identify their formation mechanism in the early solar nebula. The measurement of their shapes by using X-ray computed topography suggested that they are usually close to perfect spheres, however, some of them have rugby-ball-like (prolate) shapes [Tsuchiyama, A., Shigeyoshi, R., Kawabata, T., Nakano, T., Uesugi, K...
Element abundance ratios have been used to both distinguish terrestrial and martian basalts and make estimates on the bulk planetary chemistry. However, these estimates are based upon ratios that are assumed to have been unaffected by igneous processes. Since the extent to which this is valid is unknown, comparisons of terrestrial and martian rocks are best conducted on rocks with similar mineralogy...
We have used near-infrared spectroscopic observations of the Venus nightside taken with the Infrared Imager and Spectrograph 2 (IRIS2) on the Anglo–Australian Telescope to derive temperature maps for the Venus mesosphere at an altitude of ∼95 km. The temperatures are derived from the distribution of rotational line intensities in the O 2 (aΔg1) airglow band at 1.27 μm. To obtain reliable temperatures...
Recent gully deposits on Mars have been attributed to both wet and dry mass wasting processes. In this paper frosted granular flow (FGF) is presented as a new hypothesis for recent mass wasting activity in martian gullies. FGF is a rare type of granular flow observed on a talus slope in the Province of Québec, Canada [Hétu, B., van Steijn, H., Vandelac, P., 1994. Géogr. Phys. Quat. 48, 3–22]. Frost...
Mariner 10 clear filter (490 nm) images of Mercury were recalibrated and photometrically normalized to produce a mosaic of nearly an entire hemisphere of the planet. Albedo contrasts are slightly larger than seen in the lunar highlands (excluding maria). Variegations indicative of compositional differences include diffuse low albedo units often overlain by smooth plains, the high albedo smooth plains...
We study the influence of an open cluster environment on the formation and current structure of the Oort cloud. To do this, we have run 19 different simulations of the formation of the Oort cloud for 4.5 Gyrs. In each simulation, the Solar System spends its first 100 Myrs in a different open cluster environment before transitioning to its current field environment. We find that, compared to forming...
This paper presents an updated stratigraphical and compositional study of the exposed maria within the Imbrium basin on the Moon. Clementine multispectral data were employed to derive TiO 2 and FeO wt% abundance estimates of potentially distinct basaltic flows. Additionally, NASA Lunar Orbiter images were used to estimate flow ages using crater count statistics. Mare Imbrium shows evidence...
We vapor deposit at 20 K a mixture of gases with the specific Enceladus plume composition measured in situ by the Cassini INMS [Waite, J.H., Combi, M.R., Ip, W.H., Cravens, T.E., McNutt, R.L., Kasprzak, W., Yelle, R., Luhmann, J., Niemann, H., Gell, D., Magee, B., Fletcher, G., Lunine, J., Tseng, W.L., 2006. Science 311, 1419–1422] to form a mixed molecular ice. As the sample is slowly warmed, we...
A preliminary model of the internal magnetic field of the Moon is developed using a novel, correlative technique on the low-altitude Lunar Prospector magnetic field observations. Subsequent to the removal of a simple model of the external field, an internal dipole model is developed for each pole-to-pole half-orbit. This internal dipole model exploits Lunar Prospector's orbit geometry and incorporates...
A one-dimensional composition model of Titan's upper atmosphere is constructed, coupling 36 neutral species and 47 ions. Energy inputs from the Sun and from Saturn's magnetosphere and updated temperature and eddy coefficient parameters are taken into account. A rotating technique at constant latitude and varying local-time is proposed to account for the diurnal variation of solar inputs. The contributions...
Nitrogen isotopes appear to be escaping from Mars at approximately the primordial ratio 14 N/ 15 N ≈ 275 and to have an atmospheric nitrogen depletion time scale of about 800 Myr. For the standard model of a progressive decline of an initial inventory of atmospheric nitrogen, having no source of N, the agreement of the isotopic ratio of escaping N with primitive nitrogen would be coincidental...
Formation of chasms in the polar ice caps of Mars has been attributed to meltwater outburst floods, but the cause of melting has remained uncertain. In a cap re-entrant enveloping Abalos Colles, west of Casma Boreale in the north polar cap, we have found possible evidence of recent volcano–ice interaction and outburst flooding. In this paper we demonstrate that these two mechanisms can have acted...
Three continuum images of Comet C/2000 WM 1 (LINEAR) obtained on Nov 10, Nov 19, and Dec 03, 2001, are analyzed with the aid of a dynamical model, i.e. with a model that uses the size-dependent motion of dust grains under solar radiation pressure to determine the dust size distribution and its temporal change. The frames are photometrically calibrated in terms of the albedo filling factor...
Cone fields of ambivalent origin exist in the Elysium, Amazonis, Cerberus, Isidis, Acidalia and Cydonia regions of Mars. Considerable interest exists in regard to their location and origin as their occurrence in many instances, is most likely associated with near surface ground ice; the presence of which has consequences for past and present climate, astrobiological activity, and future exploration...
Ultraviolet and near-infrared observations of auroral emissions from the footprint of Io's magnetic Flux Tube (IFT) mapping to Jupiter's ionosphere have been interpreted via a combination of the unipolar inductor model [Goldreich, P., Lynden-Bell, D., 1969. Astrophys. J. 156, 59–78] and the multiply-reflected Alfvén wave model [Belcher, J.W., 1987. Science 238, 170–176]. While both models successfully...
We describe a strategy for scheduling astrometric observations to minimize the number required to determine the mutual orbits of binary transneptunian systems. The method is illustrated by application to Hubble Space Telescope observations of (42355) Typhon–Echidna, revealing that Typhon and Echidna orbit one another with a period of 18.971±0.006 days and a semimajor axis of 1628±29 km, implying a...
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