Search Publications
Orbital detection and implications of akaganéite on Mars
Le Deit, Laetitia; Carter, John; Loizeau, Damien +2 more
The martian surface bears the mineralogical record of ancient sub-surface and surface aqueous alteration environments. While most of the chemical alteration produced phyllosilicates, hydrated sulfates and chlorides, other less common compounds provide key constraints on localized geochemical settings, and help refine the geological evolution of th…
Sulfur in the early martian atmosphere revisited: Experiments with a 3-D Global Climate Model
Forget, François; Kerber, Laura; Wordsworth, Robin
Volcanic SO2 in the martian atmosphere has been invoked as a way to create a sustained or transient greenhouse during early martian history. Many modeling studies have been performed to test the feasibility of this hypothesis, resulting in a range of conclusions, from highly feasible to highly improbable. In this study we perform a wide…
Present-day seasonal gully activity in a south polar pit (Sisyphi Cavi) on Mars
Hiesinger, H.; Vincendon, M.; Ruesch, O. +3 more
The large amount of multi-temporal high-resolution images acquired in the last few years offers the opportunity to identify morphological changes associated with recent geologic activity on the surface of Mars. In this study we focus on a single gully in Sisyphi Cavi, located in the south polar region at 1.44°E and 68.54°S. The gully incises the g…
Vertical profiles of H2O, H2SO4, and sulfuric acid concentration at 45-75 km on Venus
Krasnopolsky, Vladimir A.
A method developed by Krasnopolsky and Pollack (Krasnopolsky, V.A., Pollack, J.B. [1994]. Icarus 109, 58-78) to model vertical profiles of H2O and H2SO4 vapors and sulfuric acid concentration in the Venus cloud layer has been updated with improved thermodynamic parameters for H2O and H2SO…
Titan's atmosphere as observed by Cassini/VIMS solar occultations: CH4, CO and evidence for C2H6 absorption
Nicholson, Philip D.; Maltagliati, Luca; Bézard, Bruno +6 more
We present an analysis of the VIMS solar occultations dataset, which allows us to extract vertically resolved information on the characteristics of Titan's atmosphere between ∼100 and 700 km with a vertical resolution of ∼10 km. After a series of data treatment procedures to correct problems in pointing stability and parasitic light, 4 occultation…
Constraints on a potential aerial biosphere on Venus: I. Cosmic rays
Coates, Andrew J.; Jones, Geraint H.; Patel, Manish R. +3 more
While the present-day surface of Venus is certainly incompatible with terrestrial biology, the planet may have possessed oceans in the past and provided conditions suitable for the origin of life. Venusian life may persist today high in the atmosphere where the temperature and pH regime is tolerable to terrestrial extremophile microbes: an aerial …
Coordinated Hubble Space Telescope and Venus Express Observations of Venus' upper cloud deck
Bertaux, Jean-Loup; Marcq, Emmanuel; Wilson, Colin +10 more
Hubble Space Telescope Imaging Spectrograph (HST/STIS) UV observations of Venus' upper cloud tops were obtained between 20N and 40S latitude on December 28, 2010; January 22, 2011 and January 27, 2011 in coordination with the Venus Express (VEx) mission. The high spectral (0.27 nm) and spatial (40-60 km/pixel) resolution HST/STIS data provide the …
Saturn's variable thermosphere from Cassini/UVIS occultations
Sandel, B. R.; Erwin, J. T.; Strobel, D. F. +3 more
We retrieved the density and temperature profiles in Saturn's thermosphere from 26 stellar occultations observed by the Cassini/UVIS instrument. These results expand upon and complement the previous analysis of 15 Cassini/UVIS solar occultations by Saturn's upper thermosphere. We find that the exospheric temperatures based on the stellar occultati…
Long-term variations of the UV contrast on Venus observed by the Venus Monitoring Camera on board Venus Express
Schröder, S. E.; Imamura, T.; Marcq, E. +1 more
We analyze the Venus ultraviolet (UV) reflectivity as observed by the Venus Monitoring Camera on board Venus Express over 2000 orbits in the years 2006-2011. We compare several laws for the photometric correction of global images of Venus, and find that the combined law of Lambert and Lommel-Seeliger is most suitable for our study. Our analysis of…
High S/N Keck and Gemini AO imaging of Uranus during 2012-2014: New cloud patterns, increasing activity, and improved wind measurements
Sromovsky, L. A.; Fry, P. M.; Hammel, H. B. +2 more
We imaged Uranus in the near infrared from 2012 into 2014, using the Keck/NIRC2 camera and Gemini/NIRI camera, both with adaptive optics. We obtained exceptional signal to noise ratios by averaging 8-16 individual exposures in a planet-fixed coordinate system. These noise-reduced images revealed many low-contrast discrete features and large scale …