Search Publications
Dusk/dawn atmospheric asymmetries on tidally-locked satellites: O2 at Europa
Leblanc, François; Johnson, Robert E.; Oza, Apurva V.
We use a simple analytic model to examine the effect of the atmospheric source properties on the spatial distribution of a volatile in a surface-bounded atmosphere on a satellite that is tidally-locked to its planet. Spatial asymmetries in the O2 exosphere of Europa observed using the Hubble Space Telescope appear to reveal on average a…
Asteroid thermal modeling in the presence of reflected sunlight
Myhrvold, Nathan
A new derivation of simple asteroid thermal models is presented, investigating the need to account correctly for Kirchhoff's law of thermal radiation when IR observations contain substantial reflected sunlight. The framework applies to both the NEATM and related thermal models. A new parameterization of these models eliminates the dependence of th…
An empirical examination of WISE/NEOWISE asteroid analysis and results
Myhrvold, Nathan
Asteroid observations by the WISE space telescope and the analysis of those observations by the NEOWISE project have provided more information about the diameter, albedo, and other properties of approximately 164,000 asteroids, more than all other sources combined. The raw data set from this mission will likely be the largest and most important su…
Improved estimation of Mars ionosphere total electron content
Sánchez-Cano, B.; Witasse, O.; Cantini, F. +5 more
We describe an improved method to estimate the Total Electron Content (TEC) of the Mars ionosphere from the echoes recorded by the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) (Picardi et al., 2005; Orosei et al., 2015) onboard Mars Express in its subsurface sounding mode. In particular, we demonstrate that this method solve…
A planetary-scale disturbance in a long living three vortex coupled system in Saturn's atmosphere
Hueso, R.; Sánchez-Lavega, A.; Rojas, J. F. +11 more
The zonal wind profile of Saturn has a unique structure at 60°N with a double-peaked jet that reaches maximum zonal velocities close to 100 ms-1. In this region, a singular group of vortices consisting of a cyclone surrounded by two anticyclones was active since 2012 until the time of this report. Our observation demonstrates that vorti…
Particle sizes in Saturn's rings from UVIS stellar occultations 1. Variations with ring region
Colwell, J. E.; Cooney, J. H.; Esposito, L. W.
The Cassini spacecraft's Ultraviolet Imaging Spectrograph (UVIS) includes a high speed photometer (HSP) that has observed stellar occultations by Saturn's rings with a radial resolution of ∼10 m. In the absence of intervening ring material, the time series of measurements by the HSP is described by Poisson statistics in which the variance equals t…
Constraints on water vapor and sulfur dioxide at Ceres: Exploiting the sensitivity of the Hubble Space Telescope
Roth, Lorenz
Far-ultraviolet observations of dwarf-planet (1) Ceres were obtained on several occasions in 2015 and 2016 by the Cosmic Origins Spectrograph (COS) and the Space Telescope Imaging Spectrograph (STIS), both on board the Hubble Space Telescope (HST). We report a search for neutral gas emissions at hydrogen, oxygen and sulfur lines around Ceres from …
Models of bright storm clouds and related dark ovals in Saturn's Storm Alley as constrained by 2008 Cassini/VIMS spectra
Baines, K. H.; Sromovsky, L. A.; Fry, P. M.
A 5° latitude band on Saturn centered near planetocentric latitude 36°S is known as "Storm Alley" because it has been for several extended periods a site of frequent lightning activity and associated thunderstorms, first identified by Porco et al. (2005). The thunderstorms appeared as bright clouds at short and long continuum wavelengths, and over…
Spectral and stratigraphic mapping of hydrated minerals associated with interior layered deposits near the southern wall of Melas Chasma, Mars
Liu, Yang; Goudge, Timothy A.; Wang, Alian +1 more
Orbital remote sensing data acquired from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) onboard Mars Reconnaissance Orbiter (MRO), in conjunction with other datasets, are used to perform detailed spectral and stratigraphic analyses over a portion of south Melas Chasma, Mars. The Discrete Ordinate Radiative Transfer (DISORT) mode…
Geology of central Libya Montes, Mars: Aqueous alteration history from mineralogical and morphological mapping
Jaumann, R.; Tirsch, D.; Bishop, J. L. +3 more
We analyze the emplacement chronology and aqueous alteration history of distinctive mineral assemblages and related geomorphic units near Hashir and Bradbury impact craters located within the Libya Montes, which are part of the southern rim of the Isidis Basin on Mars. We derive our results from a spectro-morphological mapping project that combine…