Aeolian bedforms formed by ice sublimation and vapor condensation on Louth crater ice, Mars.

• Main Authors: Collet, Aurore, Carpy, Sabrina, Bordiec, Maï, Massé, Marion, Bourgeois, Olivier, Conway, Susan
• Other Authors: Laboratoire de Planétologie et Géosciences UMR_C 6112 (LPG), Le Mans Université (UM)-Université d'Angers (UA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Nantes université - UFR des Sciences et des Techniques (Nantes univ - UFR ST), Nantes Université - pôle Sciences et technologie, Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ)-Nantes Université - pôle Sciences et technologie, Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ)
• Format: Conference Object
• Language: English
• Published: HAL CCSD 2022
• Subjects: [SDU.STU.PL]Sciences of the Universe [physics]/Earth Sciences/Planetology; [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology; Ice cap
• Online Access: https://hal.science/hal-04290898; https://doi.org/10.5194/epsc2022-471

International audience Introduction: Louth Crater is a 36 km diameter located at 70 °N, 103.2 °E (Fig. 1) less than 1000 km from the Martian North Polar Cap. At the center of Louth crater a perennial water ice cap ~10 km in diameter, ~250 m in width (Fig. 1) that undergoes phase changes (condensation / sublimation cycles) during the Martian year [1 - 4]. Some periodic structure at the surface of its perennial water ice cap have been observed [2]. The presence of smaller ice undulations superimposed on this periodic structure, comparable to the sublimation waves on the Martian North Polar Cap [5] could be formed during sublimation and condensation period of the water ice. The characterization of this ice waves could make it possible to specify environmental conditions favorable to their formation. The first part of the study consists of identifying these ice waves using orbital topography and imaging data, and then associating these results with data from the Martian Database [6-7] and with the scaling laws inherent to the formation of sublimation and condensation waves. Fig. 1: Louth crater in summer. CTX product J02_045439_2504_XN_70N256W Ls = 133.2° Geomorphological analysis: Methods: Digital Elevation Model (DEM) at ~100 m/pixel and MOLA elevation data at ~128 m/pixel have been coupled with imagery data from HRSC ~10 m/pixel, CTX at ~6 m/pixel and HiRISE images for more precise areas for up to 25 cm/pixel. Data were georeferenced in ESRI’s ArcMap GIS software to produce geomorphological map and analyzed to evaluate ice waves shape and spatial organization. Observations: Louth presents two units (Fig. 2). (a) Lower unit with dark stucco texture and stratifications (Fig. 3a). (b) Fresh ice overlies this older, stratified structure (Fig 3.a). This fresh ice is distributed in a non-uniform manner as shown by the kilometrics waves of about 560 m wavelength on which are superimposed decametrics waves of about 55 m wavelength which are both perpendicular to the prevailing wind (Fig 3.b). The crests of both wave ...