Search Publications
Vortices in Saturn's Northern Hemisphere (2008-2015) observed by Cassini ISS
West, Robert A.; Porco, Carolyn C.; Baines, Kevin H. +12 more
We use observations from the Imaging Science Subsystem on Cassini to create maps of Saturn's Northern Hemisphere (NH) from 2008 to 2015, a time period including a seasonal transition (i.e., spring equinox in 2009) and the 2010 giant storm. The processed maps are used to investigate vortices in the NH during the period of 2008-2015. All recorded vo…
CO2 non-LTE limb emissions in Mars' atmosphere as observed by OMEGA/Mars Express
Gondet, B.; Forget, F.; Altieri, F. +7 more
We report on daytime limb observations of Mars upper atmosphere acquired by the OMEGA instrument on board the European spacecraft Mars Express. The strong emission observed at 4.3 µm is interpreted as due to CO2 fluorescence of solar radiation and is detected at a tangent altitude in between 60 and 110 km. The main value of OMEGA …
Potential vorticity of the south polar vortex of Venus
Hueso, R.; Sánchez-Lavega, A.; García Muñoz, A. +1 more
Venus' atmosphere shows highly variable warm vortices over both of the planet's poles. The nature of the mechanism behind their formation and properties is still unknown. Potential vorticity is a conserved quantity when advective processes dominate over friction and diabatic heating and is a quantity frequently used to model balanced flows. As a s…
Variability of the nitric oxide nightglow at Venus during solar minimum
Montmessin, F.; Marcq, E.; Royer, E. M.
We present results from a NO airglow inversion method based on Venus Express data acquired from 2006 to 2010, during the last solar minimum period. We retrieve an altitude of 114 ± 10 km for the emission peak of the NO layer, with an associated scale height of 20 ± 10 km and an average limb brightness of 59.3 kR with a standard deviation of 63 kR.…
Assessing the mineralogy of the watershed and fan deposits of the Jezero crater paleolake system, Mars
Mustard, John F.; Goudge, Timothy A.; Head, James W. +2 more
We present results from geomorphic mapping and visible to near-infrared spectral analyses of the Jezero crater paleolake basin and its associated watershed. The goal of this study is to understand the provenance of the sedimentary deposits within this open-basin lake using a source-to-sink approach. Two fan deposits located within the basin have d…
The Martian atmospheric ion escape rate dependence on solar wind and solar EUV conditions: 1. Seven years of Mars Express observations
Barabash, Stas; Nilsson, Hans; Holmström, Mats +3 more
More than 7 years of ion flux measurements in the energy range 10 eV-15 keV have allowed the ASPERA-3/IMA (Analyzer of Space Plasmas and Energetic Ions/Ion Mass Analyzer) instrument on Mars Express to collect a large database of ion measurements in the Mars environment, over a wide range of upstream solar wind (density and velocity) and radiation …
Variability of the Martian thermosphere during eight Martian years as simulated by a ground-to-exosphere global circulation model
Forget, F.; López-Valverde, M. A.; García-Comas, M. +3 more
Using a ground-to-exosphere general circulation model for Mars we have simulated the variability of the dayside temperatures at the exobase during eight Martian years (MY, from MY24 to MY31, approximately from 1998 to 2013), taking into account the observed day-to-day solar and dust load variability. We show that the simulated temperatures are in …
Structural mapping of Enceladus and implications for formation of tectonized regions
Crow-Willard, Emma N.; Pappalardo, Robert T.
Global structural mapping of high-resolution Cassini images of Enceladus reveals a richly varied surface. Most notable are three main regions of deformation each containing multiple structural units. In addition to the well known "South Polar Terrain" (SPT), there are two other large regions of deformation that we term "Leading Hemisphere Terrain"…
Cooling of the Martian thermosphere by CO2 radiation and gravity waves: An intercomparison study with two general circulation models
Medvedev, Alexander S.; Yiǧit, Erdal; Hartogh, Paul +3 more
Observations show that the lower thermosphere of Mars (∼100-140 km) is up to 40 K colder than the current general circulation models (GCMs) can reproduce. Possible candidates for physical processes missing in the models are larger abundances of atomic oxygen facilitating stronger CO2 radiative cooling and thermal effects of gravity wave…
Morphometry of small recent impact craters on Mars: Size and terrain dependence, short-term modification
Watters, W. A.; Geiger, L. M.; Fendrock, M. +1 more
Most recent studies of crater morphometry on Mars have addressed large craters (D>5 km) using elevation models derived from laser altimetry. In the present work, we examine a global population of small (25 m ≤D≤5 km), relatively well-preserved simple impact craters using HiRISE stereo-derived elevation models. We find that scaling laws from pri…