Analysis of high altitude clouds in the martian atmosphere based on Mars Climate Sounder observations

International Symposium on Sun, Earth, and Life, Jun 2016, Bandung, IndonesiaInternational audienceHigh altitude clouds have been observed in the Martian atmosphere. However, their properties still remain to be characterized. Mars Climate Sounder (MCS) aboard Mars Reconnaissance Orbiter (MRO) is an instrument that measures radiances in the thermal infrared, both in limb and nadir views. It allows us to retrieve vertical profiles of radiance, temperature and aerosols. Using the MCS data and radiative transfer model coupled with an automated inversion routine, we can investigate the chemical composition of the high altitude clouds. We will present the first results on the properties of the clouds. CO2 ice is the best candidate to be the main component of some high altitude clouds due to the most similar spectral variation compared to water ice or dust, in agreement with previous studies. Using cloud composition of contaminated CO2 ice (dust core surrounded by CO2 ice) might improve the fitting result, but further study is needed

The Distinct and Surprisingly Diverse Populations and Properties of Mars Mesospheric Aerosols

International audienceAnalysis of a 2009-2016 set of MRO CRISM limb observations and contemporaneous MCS and MARCI observations yields a new and uniquely comprehensive characterization of dust and ice aerosol distributions and physical characteristics in the Mars mesosphere (50-100 km). Key conclusions are: [1] very distinct aphelion (Ls=0-160º) and perihelion (Ls=160-360º) aerosol populations, in which low latitude CO2 clouds at 60-70 km altitudes dominate the aphelion mesosphere and H2O ice clouds at 50-75 km altitudes dominate the perihelion mesosphere; [2] mesospheric H2O clouds composed of small particle sizes (Reff=0.2 μm) and CO2 cloud particles exhibiting a very broad range of particle sizes (Reff=0.3-2.5 μm) with small particle sizes prominent at the latitude/altitude boundaries of mesospheric CO2 cloud formation; [3] infrequent mesospheric dust aerosols in these non-planet encircling dust storm years with small particle sizes (Reff=0.3-0.6 μm); [4] MCS temperature measurements indicating saturation conditions in the vicinity of mesospheric ice aerosols and enhanced solar heating in the presence of dust aerosols; [5] very narrow CO2 particle size distributions (Veff=0.01-0.03) indicative of iridescence and rapid, uniform cloud nucleation; [6] MCS-CRISM comparisons indicating comparable daytime (3pm) CO2 cloud particle sizes but also MCS nighttime (3am) measurements indicating pervasive low latitude mesospheric CO2 clouds at lower altitudes (55-65 km) and with larger particle sizes (Reff=4-6 μm); [7] MARCI imaging of mesospheric ice clouds displaying wave forms indicative of gravity-wave forcing; and [8] strong indications that cloud nucleation centers, whatever they may be, are not lacking in Mars' mesosphere

New-Frontiers (NF) Class In-Situ Exploration of Venus: The Venus Climate and Geophysics Mission Concept

International audienceMore than 85% of the 23 investigations developed by VEXAG are largely accomplished via a NF mission centered on a variable-altitude balloon (aerobot) supported by a science/comm orbiter. Circling Venus >15 times over ~90 days, the aerobot repeatedly visits 52-62 km alts as it semi-continuously samples a host of environmental & surface parameters

New-Frontiers (NF) Class In-Situ Exploration of Venus: The Venus Climate and Geophysics Mission Concept

More than 85% of the 23 investigations developed by VEXAG are largely accomplished via a NF mission centered on a variable-altitude balloon (aerobot) supported by a science/comm orbiter. Circling Venus >15 times over ~90 days, the aerobot repeatedly visits 52–62 km alts as it semi-continuously samples a host of environmental & surface parameters