20-EPN-054: Understanding large aeolian ripples on Mars through wind tunnel experiments
Visit by Simone Silvestro, INAF Osservatorio Astronomico di Capodimonte (Italy), and Hezi Yizhaq, Midreshet Ben-Gurion (Israel), to TA2.4 Planetary Environment Facilities (PEF), AU (Denmark)
Dates of visit: 04-08 April 2022
Report summary: In our experiments in the Planetary Environment Facility in Aarhus we obtained, for the first time, two superimposed ripple patterns on monodisperse sand beads in CO2 air.
The presence of two distinct sets of aeolian sand ripples in unimodal sand suggests two formational mechanisms. Morphological characteristics such as straight crests and regular spacing point toward an impact mechanism to be responsible for the formation of the smaller (cm-scale) ripples. Conversely, the higher sinuosity of the larger (decimeter) ripples suggest a different type instability (hydrodynamic) at work. We also detect an increase in sizes for the ripples with decreasing pressure which is currently under investigation.
Collectively, our work seem to confirm the hydrodynamic nature hypothesised for the large Martian ripples.
Read the full scientific report, with kind permission from Simone Silvestro.