Search Publications
The Influence of Cloud Condensation Nucleus Coagulation on the Venus Cloud Structure
Barth, Erika L.; McGouldrick, Kevin
We present the Venus version of PlanetCARMA and demonstrate the significance of coagulation properties on the structure of the Venus cloud system. The composition of the smallest mode of particles in the Venus atmosphere, which likely serve as cloud condensation nuclei (CCN), is unknown. Here we demonstrate that a change in the ability of CCN to g…
The Enigmatic Abundance of Atomic Hydrogen in Saturn's Upper Atmosphere
West, Robert A.; Ballester, Gilda E.; Moses, Julianne I. +5 more
A planet's Lyα emission is sensitive to its thermospheric structure. Here we report joint Hubble Space Telescope and Cassini cross-calibration observations of the Saturn Lyα emission made 2 weeks before the Cassini grand finale. To investigate the long-term Saturn Lyα airglow observed by different ultraviolet instruments, we cross-correlate their …
Temporal Evolution of Titan's Stratospheric Temperatures and Trace Gases from a Two-dimensional Retrieval of Cassini Composite Infrared Spectrometer Data
Achterberg, Richard K.
We use a two-dimensional (2D) radiative transfer model of Titan, which allows the atmospheric structure to vary in both altitude and latitude, to retrieve the spatial distribution of temperature, haze extinction, and C2H2, C2H6, C3H8, CH3C2H, C4H
Constraints on Europa's Water Group Torus from HST/COS Observations
Tsuchiya, Fuminori; Saur, Joachim; Roth, Lorenz +8 more
In situ plasma measurements as well as remote mapping of energetic neutral atoms around Jupiter provide indirect evidence that an enhancement of neutral gas is present near the orbit of the moon Europa. Simulations suggest that such a neutral gas torus can be sustained by escape from Europa's atmosphere and consists primarily of molecular hydrogen…
A Geologic Map of Vesta Produced Using a Hybrid Method for Incorporating Spectroscopic and Morphologic Data
Williams, David A.; Aileen Yingst, R.; Berman, Daniel C. +3 more
We have constructed a global geologic map of the minor planet Vesta at 1:300,000-scale using Dawn spacecraft imaging, spectroscopic, topographic, and elemental data. In this effort, we used a mapping method that requires creating two maps independently: the first map uses morphology and topography to define map units, while the second map relies o…
Spectral Analysis of Clay-bearing Outcrops in Northern Xanthe Terra, Mars: Comparison with Oxia Planum, the Landing Site for the ExoMars Rover Mission
Altieri, Francesca; Brossier, Jeremy; De Sanctis, Maria Cristina +5 more
Clay minerals detected on Mars are valuable targets to seek traces of life on the planet, where biosignatures might be preserved. Here, we report an in-depth spectral analysis of clay-rich outcrops identified in northern Xanthe Terra (300°-320° E, 10°-20° N). We focused particularly on the absorptions centered in the 1.0-2.6 µm spectral rang…
The Evolution of Activity and Chemical Composition in Rosetta's Comet Targets across Multiple Apparitions: Complications for CS2 as the CS Parent in Comet Nuclei
Parker, Joel Wm.; Harris, Walter M.; Bodewits, Dennis +9 more
Jupiter-family comets are ephemeral small bodies injected into the inner solar system from the Kuiper Belt, doomed to either sublimate all their volatiles and become inert or violently shatter from the activity. We investigate two target candidates of the ESA Rosetta mission, comets 46P/Wirtanen and 67P/Churyumov-Gerasimenko, which had favorable a…
Updated Radiative Transfer Model for Titan in the Near-infrared Wavelength Range: Validation against Huygens Atmospheric and Surface Measurements and Application to the Cassini/VIMS Observations of the Dragonfly Landing Area
Le Mouélic, S.; Cornet, T.; Rodriguez, S. +13 more
We present an analysis of Titan data acquired by the Cassini Visual and Infrared Mapping Spectrometer (VIMS) at the landing site of the Dragonfly mission, using a new version of our radiative transfer model for Titan, with significant updates for the spectroscopic parameters of atmospheric gases and photochemical aerosols. Our updated radiative tr…
New Insights into Variations in Enceladus Plume Particle Launch Velocities from Cassini-VIMS Spectral Data
Hedman, M. M.; Sharma, H.; Vahidinia, S.
Enceladus's plume consists mainly of a mixture of water vapor and solid ice particles that may originate from a subsurface ocean. The physical processes underlying Enceladus's plume particle dynamics are still being debated, and quantifying the particles' size distribution and launch velocities can help constrain these processes. Cassini's Visual …
The Challenge of Measuring Asteroid Masses with Gaia DR2 Astrometry
Murray, Zachary
The Gaia second data release (DR2) contains high-accuracy astrometric measurements of thousands of solar system bodies. These measurements raise the possibility of determining asteroid masses by modeling scattering events between massive objects observed by Gaia. In this paper, we identify promising encounters between small asteroids that occur du…