Cellular patterns and dry convection in textured dust storms at the edge of Mars North Polar Cap

We present a study of textured local dust storms that develop at the northern polar cap boundary on Mars springtime. We have used images obtained with VMC and HRSC cameras onboard Mars Express and MARCI on MRO to analyze dust storms captured from March to July 2019 (Ls = 350° in MY 34–Ls = 54° in MY 35). The textured storms grow in the longitude sector 150°E-210°E centered at latitude ~60°N and exhibit spiral, filamentary and compact shapes that change and evolve rapidly in a daily basis. The storms translate by prevailing east and southeast winds with speeds 15–45 ms−1. In some areas of their interiors they show organized clusters of cells formed typically by 100 elements with sizes ~5–30 km with a length/width ratio ~ 1.2–3 in the wind direction. The cells have elongated downwind tails with lengths 4–8 times the cell size. The cells top altitudes are ~6–11 km above their surroundings. We propose that the spirals grow as baroclinic vortices within a vertically sheared eastward jet present at this epoch in Mars due to the intense meridional temperature gradient at the polar cap edge. We show using a simple one-dimensional model that the cells can be produced by shallow dry convection with dust acting as the heating source to generate the updrafts. These patterns resemble those seen in laboratory experiments and on clouds in Earth's atmosphere and can serve to comparatively elucidate and discern the different mechanisms at work in each case

Mars Express and Trace Gas Orbiter: status, science highlights, plans

Stars and planetary systemsLaboratory astrophysics and astrochemistr

Dynamics of the extremely elongated cloud on Mars Arsia Mons volcano

Starting in September 2018, a daily repeating extremely elongated cloud was observed extending up to 1800km from the Mars Arsia Mons volcano. We study this Arsia Mons Elongated Cloud (AMEC) using images from VMC, HRSC, and OMEGA on board Mars Express, IUVS on MAVEN, MCC on Mars Orbiter Mission (MOM), MARCI on MRO, and Visible Camera on Viking 2 orbiter. We study the daily cycle of this cloud, showing how the morphology and other parameters of the cloud evolved rapidly with local time. The cloud expands every morning from the western slope of the volcano, at a westward velocity of around 160m/s, and an altitude of around 45km over martian areoid. The expansion starts with sunrise, and resumes around 2.5 hours later, when cloud formationresumes and the elongated tail detaches from the volcano and keeps moving westward until it evaporates before afternoon, when most sun-synchronous missions observe. This daily cycle repeated regularly for at least 80 sols in 2018 (Martian Year 34). We find in images from past years that this AMEC is an annually repeating phenomenon that takes place around the Solar Longitude range 220º-320º. We study the AMEC in Martian Year 34 in terms of Local Time and Solar Longitude, and then compare with observations from previous years, in search for interannual variations, taking into account the possible influence of the recent Global Dust Storm

Dynamics of the extremely elongated cloud on Mars Arsia Mons volcano

Starting in September 2018, a daily repeating extremely elongated cloud was observed extending from the Mars Arsia Mons volcano. We study this Arsia Mons Elongated Cloud (AMEC) using images from VMC, HRSC, and OMEGA on board Mars Express, IUVS on MAVEN, and MARCI on MRO. We study the daily cycle of this cloud, showing how the morphology and other parameters of the cloud evolved with local time. The cloud expands every morning from the western slope of the volcano, at a westward velocity of around 150m/s, and an altitude of around 30-40km over the local surface. Starting around 2.5 hours after sunrise (8.2 Local True Solar Time, LTST), the formation of the cloud resumes, and the existing cloud keeps moving westward, so it detaches from the volcano, until it evaporates in the following hours. At this time, the cloud has expanded to a length of around 1500km. Short time later, a new local cloud appears on the western slope of the volcano, starting around 9.5 LTST, and grows during the morning. This daily cycle repeated regularly for at least 90 sols in 2018, around Southern Solstice (Ls 240-300) in Martian Year (MY) 34. According with these and previous MEx/VMC observations, this elongated cloud is a seasonal phenomenon occurring around Southern Solstice every Martian Year. We study the interannual variability of this cloud, the influence of the Global Dust Storms in 2018 on the cloud’s properties (Sánchez-Lavega et al., Geophys. Res. Lett. 46, 2019), and its validity as a proxy for the global state of the Martian atmosphere (Sánchez-Lavega et al., J. Geophys. Res., 123, 3020, 2018). We discuss the physical mechanisms behind the formation of this peculiar cloud in Mars

Mars Express: 20 Years of Mission, Science Operations and Data Archiving

Full list of the authors: Cardesin-Moinelo, A.; Godfrey, J.; Grotheer, E.; Blake, R.; Damiani, S.; Wood, S.; Dressler, T.; Bruno, M.; Johnstone, A.; Lucas, L.; Marin-Yaseli de la Parra, J.; Merritt, D.; Sierra, M.; Määttänen, A.; Antoja-Lleonart, G.; Breitfellner, M.; Muniz, C.; Nespoli, F.; Riu, L.; Ashman, M.; Escalante, A.; Geiger, B.; Heather, D.; Hepburn, A.; Pistone, V.; Raga, F.; Valles, R.; Companys, V.; Martin, P.; Wilson, C.Launched on 2 June 2003 and arriving at Mars on 25 December 2003 after a 7-month interplanetary cruise, Mars Express was the European Space Agency’s first mission to arrive at another planet. After more than 20 years in orbit, the spacecraft and science payload remain in good health and the mission has become the second oldest operational planetary orbiter after Mars Odyssey. This contribution summarizes the Mars Express mission operations, science planning and data archiving systems, processes, and teams that are necessary to run the mission, plan the scientific observations, and execute all necessary commands. It also describes the data download, the ground processing and distribution to the scientific community for the study and analysis of Mars sub-surface, surface, atmosphere, magnetosphere, and moons. This manuscript also describes the main challenges throughout the history of the mission, including several potentially mission-ending anomalies. We summarize the evolution of the ground segment to provide new capabilities not envisaged before launch, whilst simultaneously maintaining or even increasing the quality and quantity of scientific data generated. © The Author(s) 2024The authors thank the International Space Science Institute (ISSI) in Bern, Switzerland for the support and acknowledge the contributions of the European Space Agency, and all other National Agencies, research institutions and teams involved in the success of the Mars Express mission. IAA-CSIC team is supported by grant PID2022-137579NB-I00 funded by MCIN/AEI/10.13039/501100011033 and by "ERDF A way of making Europe"

Hydroxyl nightglow on Venus observed by VIRTIS on Venus-Express

Hydroxyl has been recently observed for the first time in the Venus atmosphere with the VIRTIS spectrometer on board the Venus-Express spacecraft. The (1-0) around 2.81 microns and the (2-0) around 1.46 microns transitions have been detected. The intensity of the two emissions are respectively about 55 and 480 times less intense than the (0-0) oxygen transition (Piccioni et al, A&A, 2008). The possible chemical reactions which can produce hydroxyl on Venus involve O3 and HO2, with the former being the most probable, and hence OH can be used to indirectly infer the ozone distribution on Venus. VIRTIS data in limb mode observation were analyzed to derive the mean distribution of hydroxyl in the night side of Venus and the results are presented here. The typical peak altitude of the two emissions is set at 95-96 km in limb view, a few km lower than the oxygen emission at 1.27 um due to the transition (0-0). The peak altitude of the latter typically occurs at 97-98 km height. The OH full width at half maximum is in average about 7 km, and sometimes higher. The mean map of (1-0) hydroxyl distribution around 2.81 microns shows a maximum of emission of about 130 kR at about 1h local time. The study of the (2-0) hydroxyl distribution at around 1.46 microns results more difficult due to its weak intensity

Near-IR oxygen nightglow observed by VIRTIS in the Venus upper atmosphere

[1] We present observations of both the (0-0) and (0-1) bands at 1.27 and 1.58 μm of the O2(a1 Δg - X3Σg-) nightglow made with the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) instrument aboard Venus Express. The observations were conduc

Global maps of Venus nightside mean infrared thermal emissions obtained by VIRTIS on Venus Express

International audienceOne of the striking features about Venus atmosphere is its temporal variability and dynamics, with a chaotic polar vortex, large-scale atmospheric waves, sheared features and variable winds that depend on local time and possibly orographic features. The aim of this research is to combine data accumulated over several years and obtain a global mean state of the atmosphere focusing in the global structure of the clouds using the cloud opacity and upper cloud temperatures.We have first produced global maps using the integrated radiance through the infrared atmospheric windows centred around 1.74 μm and 2.25 μm, that show the spatial variations of the cloud opacity in the lower clouds around 44–48 km altitude and also provide an indirect estimation of the possible particle size. We have also produced similar global maps using the brightness temperatures seen in the thermal region at 3.8 μm and 5.0 μm, which provide direct indication of the temperatures at the top of the clouds around 60–70 km altitude.These maps have been generated using the complete dataset of the Visible and InfraRed Thermal Imaging Spectrometer mapping channel (VIRTIS-M) on board Venus Express, with a wide spatial and long temporal coverage in the period from May 2006 until October 2008.Our results provide a global view of the cloud opacity, particle size and upper cloud temperatures at both hemispheres, showing the main different dynamical regions of the planet. The profiles obtained also provide the detailed dependencies with latitude, local time and longitude, diagnostic of the global circulation flow and dynamics at various altitude layers, from about 44 up to 70 km over the surface