Search Publications
Composition and structure of fresh ammonia clouds on Jupiter based on quantitative analysis of Galileo/NIMS and New Horizons/LEISA spectra
Sromovsky, L. A.; Fry, P. M.
Ammonia gas has long been assumed to be the main source of condensables for the upper cloud layer on Jupiter, but distinctive spectral features associated with ammonia have been seen only rarely. Since both ammonia and NH4SH absorb in the 3 µm region, and widespread absorption in the 3 µm region was present (Sromovsky and Fr…
Stepped fans and facies-equivalent phyllosilicates in Coprates Catena, Mars
Warner, N. H.; Gupta, S.; Grindrod, P. M. +2 more
Stepped fan deposits and phyllosilicate mineralogies are relatively common features on Mars but have not previously been found in association with each other. Both of these features are widely accepted to be the result of aqueous processes, but the assumed role and nature of any water varies. In this study we have investigated two stepped fan depo…
Constraining the parameter space of comet simulation experiments
Hagermann, Axel; Kaufmann, Erika
Our interpretation of the data returned by Rosetta and other cometary missions is based on the predictions of theoretical models and the results of laboratory experiments. For example, Kossacki et al. (2015) showed that 67P's surface hardness reported by Spohn et al. (2015) can be explained by sintering. The present work supports Rosetta's observa…
The upcoming mutual event season for the Patroclus-Menoetius Trojan binary
Buie, M. W.; Grundy, W. M.; Noll, K. S. +1 more
We present new Hubble Space Telescope and ground-based Keck observations and new Keplerian orbit solutions for the mutual orbit of binary Jupiter Trojan asteroid (617) Patroclus and Menoetius, targets of NASA's Lucy mission. We predict event times for the upcoming mutual event season, which is anticipated to run from late 2017 through mid 2019.
Regional stratigraphy of the south polar layered deposits (Promethei Lingula, Mars): "Discontinuity-bounded" units in images and radargrams
Thomas, Nicolas; Forget, François; Rossi, Angelo Pio +5 more
The Mars South Polar Layered Deposits (SPLD) are the result of depositional and erosional events, which are marked by different stratigraphic sequences and erosional surfaces. To unambiguously define the stratigraphic units at regional scale, we mapped the SPLD on the basis of observed discontinuities (i.e., unconformities, correlative discontinui…
Compressive strength and elastic modulus at Agilkia on comet 67P/Churyumov-Gerasimenko derived from the SESAME/CASSE touchdown signals
Flandes, Alberto; Krüger, Harald; Arnold, Walter +8 more
We report an analysis of the Comet Acoustic Surface Sounding Experiment (CASSE) acceleration signals at Philae's first touchdown site Agilkia on comet 67P/Churyumov-Gerasimenko. The signals yield the forces in the contact zone foot-sole and comet surface, and from these forces a compression strength of approximately 10 kPa can be derived. The sole…
Large catchment area recharges Titan's Ontario Lacus
Barnes, Jason W.; Kirk, Randolph L.; Dhingra, Rajani D. +1 more
We seek to address the question of what processes are at work to fill Ontario Lacus while other, deeper south polar basins remain empty. Our hydrological analysis indicates that Ontario Lacus has a catchment area spanning 5.5% of Titan's surface and a large catchment area to lake surface area ratio. This large catchment area translates into large …
Aerosol properties in the upper clouds of Venus from glory observations by the Venus Monitoring Camera (Venus Express mission)
Markiewicz, Wojciech J.; Petrova, Elena V.; Shalygina, Oksana S.
From the angular positions of the glory features observed on the upper cloud deck of Venus in three VMC channels (at 0.365, 0.513, and 0.965 µm), the dominating sizes of cloud particles and their refractive indices have been retrieved, and their spatial and temporal variations have been analyzed. For this, the phase profiles of brightness we…
Glory on Venus and selection among the unknown UV absorbers
Petrova, Elena V.
The comparison of the phase profiles of glories observed on the cloud top of Venus by the Venus Monitoring Camera (Venus Express) and the light-scattering characteristics of sulfuric acid droplets, containing admixtures with a high refractive index, makes it easier to choose between some candidates for the so-called unknown UV absorber in the Venu…
Mars radar clutter and surface roughness characteristics from MARSIS data
Schroeder, Dustin M.; Whitten, Jennifer L.; Campbell, Bruce A.
Radar sounder studies of icy, sedimentary, and volcanic settings can be affected by reflections from surface topography surrounding the sensor nadir location. These off-nadir ;clutter; returns appear at similar time delays to subsurface echoes and complicate geologic interpretation. Additionally, broadening of the radar echo in delay by surface re…