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Strong MARSIS Radar Reflections From the Base of Martian South Polar Cap May Be Due to Conductive Ice or Minerals
Putzig, N. E.; Bierson, C. J.; Tulaczyk, S. +1 more
Recent results from the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) instrument have been interpreted as evidence of subsurface brine pooled beneath 1.3 km-thick South Polar Layered Deposit (SPLD). This interpretation is based on the assumption that the regionally high strength of MARSIS radar reflections from the base of th…
A Solid Interpretation of Bright Radar Reflectors Under the Mars South Polar Ice
Smith, I. B.; Horgan, B. H. N.; Whitten, J. L. +4 more
Bright radar reflections observed beneath the south polar layered deposits (SPLD) by the Mars Advanced Radar for Subsurface and Ionosphere Sounding instrument were interpreted to represent liquid water, but the required amounts of salt and heat to form and maintain liquids in this location are implausible given what is known about Mars. Here, we p…
Periodic Bedrock Ridges at the ExoMars 2022 Landing Site: Evidence for a Changing Wind Regime
Pajola, M.; Tirsch, D.; Silvestro, S. +11 more
Wind formed features are abundant in Oxia Planum (Mars), the landing site of the 2022 ExoMars mission, which shows geological evidence for a past wet environment. Studies of aeolian bedforms at the landing site were focused on assessing the risk for rover trafficability, however their potential in recording climatic fluctuations has not been explo…
Characteristics of the Basal Interface of the Martian South Polar Layered Deposits
Plaut, Jeffrey J.; Khuller, Aditya R.
We expand on previous studies of the South Polar Layered Deposits' (SPLD) basal interface using data acquired by the Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) to obtain detailed maps of elevation, topography, and reflected radar power. Using these maps, we derive the thickness (ranging from 0 to 3.7 km) and volume of the…
Delta Deposits on Mars: A Global Perspective
Hauber, E.; Breuer, D.; De Toffoli, B. +1 more
Deltas have long been considered a constraining element to reconstruct the water level of an ancient ocean that may have once occupied the northern lowlands of Mars, and recently this hypothesis started to be challenged. We investigate this hypothesis and present a global inventory of fan-shaped features showing typical deltaic traits across the e…
A Long Term Study of Mars Mesospheric Clouds Seen at Twilight Based on Mars Express VMC Images
Hueso, R.; Sánchez-Lavega, A.; Titov, D. +5 more
We present the first systematic study of clouds observed during twilight on Mars. We analyze images obtained by the Visual Monitoring Camera on Mars Express between 2007 and 2020. Using an automated retrieval algorithm, we found 407 cases of clouds observed at twilight, in which the geometry of the observations allows to derive the minimum altitud…
Precipitation Driven Pedogenic Weathering of Volcaniclastics on Early Mars
Michalski, J. R.; Ye, B.
Compositional stratigraphy, generally composed of Al rich clay minerals overlying Fe/Mg rich clay minerals, is observed in many locations on Mars. Here we describe the occurrence of such mineralogical stratigraphy in settings where the protoliths are almost certainly pyroclastic materials. One such example includes altered rocks high on the summit…
Caldera Collapse as the Trigger of Chaos and Fractured Craters on the Moon and Mars
Massironi, Matteo; Rossi, Angelo Pio; Pozzobon, Riccardo +3 more
Chaotic terrains are broad regions on Mars characterized by the disruption of the basaltic bedrock into polygonal blocks separated by deep fractures. To date, the proposed genetic scenarios often involve the occurrence of subsurface ice or liquid H2O. Nevertheless, similar features also occur within some craters on the Moon, namely floo…
Alternatives to Liquid Water Beneath the South Polar Ice Cap of Mars
Steinbrügge, Gregor; Schroeder, Dustin M.
Radar sounding of Mars' south polar ice cap has revealed portions of its base with stronger radar returns than its surface. These have been used to estimate high real permittivity values consistent with liquid water. However, the thermal, chemical, and geological conditions required to sustain such water bodies are challenging to achieve in the co…
Active Boulder Falls in Terra Sirenum, Mars: Constraints on Timing and Causes
Conway, Susan J.; Grindrod, Peter M.; Davis, Joel M. +1 more
We use time series images to identify significant active boulder falls in an impact crater on Mars. Evidence for active boulder falls include boulder trails with impact marks from bouncing and rolling, and dark patches from boulder impacts away from the base of the crater walls. We were able to define three time periods with active boulder falls a…