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On the Effect of Magnetospheric Shielding on the Lunar Hydrogen Cycle
Farrell, W. M.; Tucker, O. J.; Poppe, A. R.
The global distribution of surficial hydroxyl on the Moon is hypothesized to be derived from the implantation of solar wind protons. As the Moon traverses the geomagnetic tail, it is generally shielded from the solar wind; therefore, the concentration of hydrogen is expected to decrease during full Moon. A Monte Carlo approach is used to model the…
ExoMars TGO/NOMAD-UVIS Vertical Profiles of Ozone: 2. The High-Altitude Layers of Atmospheric Ozone
Thomas, Ian; Daerden, Frank; Ristic, Bojan +12 more
Solar occultations performed by the Nadir and Occultation for MArs Discovery (NOMAD) ultraviolet and visible spectrometer (UVIS) onboard the ExoMars Trace Gas Orbiter (TGO) have provided a comprehensive mapping of atmospheric ozone density. The observations here extend over a full Mars year (MY) between April 21, 2018 at the beginning of the TGO s…
Lava Flow Eruption Conditions in the Tharsis Volcanic Province on Mars
Christensen, P. R.; Peters, S. I.; Clarke, A. B.
Volcanism has played a major role in modifying the Martian surface. The Tharsis volcanic province dominates the western hemisphere of the planet with numerous effusive volcanic constructs and deposits. Here, we present the results of an in-depth study aimed at characterizing and modeling the emplacement conditions of 40 lava flows in the Tharsis v…
Dielectric Properties of the Medusae Fossae Formation and Implications for Ice Content
Campbell, Bruce A.; Morgan, Gareth A.; Watters, Thomas R.
The extensive Medusae Fossae Formation (MFF) along the dichotomy boundary on Mars has geologic features indicative of wind erosion of low density material. There is evidence suggesting a water ice component, but with considerable uncertainty linked to the unknown MFF porosity and compaction behavior. We use SHARAD radar sounder data to estimate th…
Jupiter's Great Red Spot: Strong Interactions With Incoming Anticyclones in 2019
Hansen, C. J.; Hueso, R.; Sánchez-Lavega, A. +19 more
Jupiter's Great Red Spot (GRS), a giant anticyclone, is the largest and longest lived of all the vortices observed in planetary atmospheres. During its history, the GRS has shrunk to half its size since 1879, and encountered many smaller anticyclones and other dynamical features that interacted in a complex way. In 2018-2020, while having a histor…
A Global and Seasonal Perspective of Martian Water Vapor From ExoMars/NOMAD
Aoki, S.; Vandaele, A. C.; Daerden, F. +18 more
Slightly less than a Martian Year of nominal science (March 2018-January 2020) with the ExoMars Trace Gas Orbiter has furthered the ongoing investigation of dayside water vapor column abundance. These dayside observations span latitudes between 75°S and 75°N, and all longitudes, which can provide global snapshots of the total water column abundanc…
Isotopic Composition of CO2 in the Atmosphere of Mars: Fractionation by Diffusive Separation Observed by the ExoMars Trace Gas Orbiter
Montmessin, Franck; Belyaev, Denis A.; Fedorova, Anna A. +11 more
Isotopic ratios in atmospheric CO2 are shaped by various processes throughout Mars' history, and can help understand what the atmosphere of early Mars was like to sustain liquid water on its surface. In this study, we monitor the O and C isotopic composition of CO2 between 70 and 130 km for more than half a Martian year using…
An Extremely Elongated Cloud Over Arsia Mons Volcano on Mars: I. Life Cycle
Gondet, B.; Jaumann, R.; Hueso, R. +12 more
We report a previously unnoticed annually repeating phenomenon consisting of the daily formation of an extremely elongated cloud extending as far as 1,800 km westward from Arsia Mons. It takes place in the solar longitude (Ls) range of ∼220°-320°, around the Southern solstice. We study this Arsia Mons Elongated Cloud (AMEC) using images from diffe…
The Dayside Ionopause of Mars: Solar Wind Interaction, Pressure Balance, and Comparisons With Venus
Gurnett, D. A.; Kopf, A. J.; Halekas, J. +5 more
Due to the lower ionospheric thermal pressure and existence of the crustal magnetism at Mars, the Martian ionopause is expected to behave differently from the ionopause at Venus. We study the solar wind interaction and pressure balance at the ionopause of Mars using both in situ and remote sounding measurements from the Mars Advanced Radar for Sub…
Depositional Controls of the Layered Deposits of Arabia Terra, Mars: Hints From Basin Geometries and Stratigraphic Trends
Rossi, A. P.; Pondrelli, M.; Le Deit, L. +4 more
An extensive distribution of water-altered equatorial layered deposits (ELDs) characterizes the densely cratered terrain of Arabia Terra (AT), Mars. The majority of these deposits reside within craters and are easily identified by laterally continuous layering. The processes that led to their formation have been widely investigated, but remain unr…