Search Publications
Modification history of the Harmakhis Vallis outflow channel, Mars, based on CTX-scale photogeologic mapping and crater count dating
Kostama, V. -P.; Kukkonen, S.
Harmakhis Vallis is one of the four major outflow channel systems (Dao, Niger, Harmakhis, and Reull Valles) that cut the eastern rim region of the Hellas basin, the largest well-preserved impact structure on Mars. The structure of Harmakhis Vallis and the volume of its head depression, as well as earlier dating studies of the region, suggest that …
On the origin of internal layers in comet nuclei
Li, Jian-Yang; Belton, Michael J. S.; Asphaug, Erik +1 more
We present an analysis of the layered structure on 67P/Churyumov-Gerasimenko' s Hathor cliff and propose a mechanism (self-sustaining, dual-mode propagation of amorphous to crystalline ice phase-change fronts into the nucleus interior) for its origin. If this is a viable mechanism, the strata must be geologically young (∼106 y). The Hat…
Scale heights and detached haze layers in the mesosphere of Venus from SPICAV IR data
Montmessin, F.; Fedorova, A.; Korablev, O. +3 more
SPICAV IR, one channel of SPICAV/SOIR instrument suite onboard Venus Express, performed solar occultation measurements of the atmosphere at terminators in 0.65-1.7 µm spectral range. We analyze the properties of the upper part of the Venus aerosol layer (upper haze, 70 - 95 km altitude) from 798 observations performed from May 2006 through N…
A search for polycyclic aromatic hydrocarbons over the Martian South Polar Residual Cap
Muller, J. -P.; Sidiropoulos, P.; Campbell, J. D.
We present our research on compositional mapping of the Martian South Polar Residual Cap (SPRC), especially the detection of organic signatures within the dust content of the ice, based on hyperspectral data analysis. The SPRC is the main region of interest for this investigation, because of the unique CO2 ice sublimation features that …
Cassini UVIS solar occultations by Saturn's F ring and the detection of collision-produced micron-sized dust
Colwell, Joshua E.; Murray, Carl D.; Esposito, Larry W. +2 more
We present an analysis of eleven solar occultations by Saturn's F ring observed by the Ultraviolet Imaging Spectrograph (UVIS) on the Cassini spacecraft. In four of the solar occultations we detect an unambiguous signal from diffracted sunlight that adds to the direct solar signal just before or after the occultations occur. The strongest detectio…
Low velocity collisions of porous planetesimals in the early solar system
Kührt, E.; Davidsson, B.; Hviid, S. +1 more
The ESA Rosetta mission has shown that Comet 67P/Churuymov-Gerasimenko is bi-lobed, has a high average porosity of around 70%, does not have internal cavities on size scales larger than 10 m, the lobes could have individual sets of onion shell-like layering, and the nucleus surface contains 100 m-scale cylindrical pits. It is currently debated whe…
Ejecta deposits of Bakhuysen Crater, Mars
Tornabene, L. L.; Osinski, G. R.; Caudill, C. M.
Bakhuysen Crater is a Late Noachian to Early Hesperian age ∼150 km-diameter impact structure located in the heavily cratered southern highlands of Mars. It is one of the largest craters on Mars with well-preserved ejecta deposits. Impact ejecta deposits allow an understanding of crustal composition, volatile content, and evolution of terrestrial p…
Retrieval of H2O abundance in Titan's stratosphere: A (re)analysis of CIRS/Cassini and PACS/Herschel observations
Lellouch, E.; Irwin, P. G. J.; Teanby, N. A. +6 more
Since its first measurement 20 years ago by the Infrared Space Observatory (ISO), the water (H2O) mole fraction in Titan's stratosphere remains uncertain due to large differences between the determinations from available measurements. More particularly, the recent measurements made from the Herschel observatory (PACS and HIFI) estimated…
Internal gravity, self-energy, and disruption of comets and asteroids
Korycansky, D. G.; Dobrovolskis, Anthony R.
The internal gravity and self-gravitational energy of a comet, asteroid, or small moon have applications to their geophysics, including their formation, evolution, cratering, and disruption, the stresses and strains inside such objects, sample return, eventual asteroid mining, and planetary defense strategies for potentially hazardous objects. Thi…
The strength of ice-saturated extraterrestrial rock analogs
Seager, Sara; Atkinson, Jared; Durham, William B.
In situ resource utilization (ISRU) activities have been identified by the National Research Council as one of the most important scientific endeavors of the coming decade. The failure of the MUPUS-PEN experiment on Rosetta's Philae lander to penetrate the surface of comet 67P demands knowledge of the mechanical properties of extraterrestrial mate…