Tag: ta2.20

22-EPN3-103: Molards as Proxies of CO2 and H2O Ice Degradation Under Martian Conditions

June 4, 2023

22-EPN3-103: Molards as Proxies of CO2 and H2O Ice Degradation Under Martian Conditions – Investigating Physical Downscaled Models

Visit by Calvin Beck, Universtiy of Caen Normandy (France) to TA2.20 Open University Mars Chamber (UK).
Dates of visit: 02-20 October 2023

Report Summary: We performed the first laboratory study on the formation of molards by sublimation processes. On Earth, permafrost molards are cones of loose debris in landslide deposits that can be used as a marker for mountain permafrost retreat. They originate from ice-cemented blocks of sediment that are transported downslope with the landslide and melt to form conical mounds over time. Molard candidates in the ejecta flows of Hale Crater show similar morphology and spatial distribution to molards found on Earth. In contrast to Earth, these molards likely formed by sublimation, because water is not stable in its liquid form.

To investigate how molards that formed by sublimation could differ from those formed by melting on Earth we performed experiments at the Open University’s Mars Chamber facility. We created cylindrical (Ø13 cm) frozen blocks of sediment with either H₂O or CO₂ ice. We let the initially frozen blocks of sediment degrade in the Mars Chamber while monitoring them with a time-lapse photogrammetry system. This allowed us to quantify the volume transport during the degradation phase. We performed experiments for both ice types at terrestrial and martian pressure for coarse sand, gravel, and JSC-Mars-1. We successfully recreated conical morphologies resembling terrestrial permafrost molards for coarse sand and gravel with CO₂ and H₂O ice under Martian pressure. Our results reveal that sublimation can change the expected morphologies when the gas flux is able to entrain the sediment and has implications for interpreting sublimation morphologies on Mars and other planetary bodies where sublimation dominates.

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20-EPN-066: Experimental investigation of CO2 frost condensation and sublimation through sediments in Martian conditions

20-EPN-066: Experimental investigation of CO2 frost condensation and sublimation through sediments in Martian conditions – implications for martian gullies and jets

Visit by Camila Cesar, University of Bern (Switzerland) to TA2.20 Open University Mars Chamber (UK).
Dates of visit: 24 October – 18 November 2022

Report Summary: Our experimental campaign aimed to understand sediment transport driven by CO2 ice sublimation condensed inside a porous regolith. To quantify the erosion of sediment associated
with the sublimation of CO2 frost in the subsurface of a ~30° slope, we tested various compositions (MGS-1, sand, sand-dust mixtures). While some sediment showed little to no activity over several attempts (sand), others showed significant slope activity (sand + >=10% MGS clay).

Read the full scientific report, with kind permission from Camila Cesar.

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20-EPN2-106: The effect of ice substrate to formation of mud flows in a low-pressure environment: insights for Martian sedimentary volcanism

20-EPN2-106: The effect of ice substrate to formation of mud flows in a low-pressure environment: insights for Martian sedimentary volcanism

Visit by Ondrej Kryza, Institute of Geophysics of the Czech Academy of Sciences (Czech Republic) to TA2.20 Open University Mars Chamber (UK).
Dates of visit: 21 June – 12 July 2022

Report Summary: This project was designed to extend previous research of mud behaviour in the low-pressure conditions – with implications for potential sedimentary volcanism on Mars. The main objective was to test the effect of ice (or combined ice-sand) substrate to flow abilities and finite morphology of mudflows. As secondary objectives, testing of various inclinations of the surface, investigation of potential thermal erosion and extended study of another type of surfaces were implemented. 

In the first part of the project, nine successful experiments, with pure and variously inclined (2-10°) ice surface, confirmed a different style of mud propagation than in case of the frozen sandy surface. The major observations are: 1) dominant and prevailing boiling of mud mixture during the propagation over deeply frozen ice surface (confirms significance of latent heat related to melting/recrystallization), 2) explosive potential of ice when in contact with the boiling mud (fracturing, contraction-dilatation). The effect of slope in tested range has no significant impact on these observations.  

The second type of experiments tested combined ice-sand upper lid. Here, transition between boiling and freezing of mudflows was faster and finite morphology was more similar to lava-like flows which were described by Brož et al. (2020a). 

In both cases, the thermal erosion was not confirmed. Moreover, during sectioning and investigation of the finite mudflow shapes and their base, the developed bumps, irregularities or even increased porosity of ice lid were discovered. This might refer to more complex thermal exchange between ice and mud with a sequential melting and re-freezing. 

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20-EPN-015: Deciphering fluidisation of mass flows by metastable volatiles on extra-terrestrial bodies

October 7, 2022

20-EPN-015: Deciphering fluidisation of mass flows by metastable volatiles on extra-terrestrial bodies

Project lead: Tjalling de Haas. Visit by Lonneke Roelofs, Utrecht University, the Netherlands to TA2.20 Open University Mars Chamber (UK).
Dates of visit: 20 September – 29 October 2021

Report Summary: Martian gullies are alcove-channel-fan systems that have been hypothesized to be formed by the action of liquid water and brines, the effects of sublimating CO2 ice, or a combination of these processes. Recent activity and new flow deposits in these systems have shifted the leading hypothesis from water-based flows to CO2-driven flows, as it is hard to reconcile present activity with the low availability of atmospheric water under present Martian conditions. Direct observations of flows driven by metastable CO2 on the surface of Mars are however nonexistent, and our knowledge of CO2-driven flows under Martian conditions remains limited. For the first time, CO2-driven granular flows were produced in a small-scale flume under Martian atmospheric conditions in the Mars Chamber at the Open University (UK). The experiments were used to quantify the slope threshold and CO2 fraction limits for fluidisation. With these experiments, we show that the sublimation of CO2 can fluidize sediment and sustain granular flows under Martian atmospheric conditions. The morphology of the deposits is lobate and depends highly on the CO2-sediment ratio, sediment grain size, and flume angle. The gas-driven granular flows are sustained under low (<20o) flume angles and small volumes of CO2 (around 5% of the entire flow). Pilot experiments with sediment flowing over a layer of CO2 suggest that even smaller percentages of CO2 ice are needed for fluidisation. The data further shows that the flow dynamics are complex with surging behavior and complex pressure distribution in the flow, through time and space.

Article in the Europlanet Magazine on visit by Lonneke Roelofs.

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20-EPN-038: The strange behaviour of highly viscous mud in the low pressure environment: why the mixture changes its volume?

20-EPN-038: The strange behaviour of highly viscous mud in the low pressure environment: why the mixture changes its volume?

Visit by Petr Brož, Institute of Geophysics of the Czech Academy of Science (Czech Republic) to TA2.20 Open University Mars Chamber (UK).
Dates of visit: 6-17 December 2021

Report Summary: We performed multiple mud experiments inside a low-pressure chamber to investigate whether the volume of mud changes once exposed to the reduced atmospheric pressure of Mars. Our results show that mud extruded onto the surface under martian environmental conditions increases its volume and hence behaves differently than on Earth. The low atmospheric pressure causes instability of the water present in the mud mixture, leading to the formation of bubbles, which increase the volume of the mud.

These bubbles are then trapped within the mud. The buoyancy of the bubbles is not sufficient to overcome the drag force within the viscous material and rise to the surface. Hence, these bubbles remain trapped and gradually grow up to centimetre scale sizes. During their growth they push the mud out of the container resulting in horizontal and vertical inflation of the mud surface over cm-scales.

This behaviour is not observed at terrestrial mud flows, but it is somewhat similar to volumetric changes associated with degassing of some terrestrial lavas or mud volcano eruptions. Our experimental approach hence shows that viscous mud exposed to reduced atmospheric pressure behaves differently to on Earth.

Full scientific report published by kind permission of Petr Brož.

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20-EPN2-023: Fluidisation of mass flows by metastable volatiles on extraterrestrial bodies

December 9, 2021

20-EPN2-023: Fluidisation of mass flows by metastable volatiles on extraterrestrial bodies

Visit by Lonneke Roelofs, Utrecht University (Netherlands) to TA2.20 Open University Mars Chamber (UK).
Dates of visit: 29 September – 6 October 2021.

Abstract: On planetary bodies unlike Earth, landforms may be created that look similar to those found on Earth but are actually produced by disparate and so-far unknown processes. Therefore, extra-terrestrial landforms assumed to be created by liquid water may in fact be formed by process-volatile interactions unknown to Earth. We propose an ambitious set of laboratory simulations to quantify the environmental and physical limits of sediment mass flows triggered by metastable CO2 under reduced atmospheric pressures. The laboratory simulations become possible by a unique synergy where an experimental setup for simulating mass flows developed at Utrecht University is placed in the Mars Chamber at The Open University, to for the first time generate mass flows supported by CO2 in different phases under a range of atmospheric pressures ranging from terrestrial to martian. Advanced measurement devices allow us to measure fluidisation upon triggering, flow dynamics downslope, and deposit morphologies under controlled conditions. This will provide a major step towards solving the long-lasting debate on the possible role of present-day volatiles in martian gully formation and its paleoclimatic implication. Our results will inform future mission-planning, and open up new understanding of slope processes on other planetary bodies.

Read report in the Europlanet Magazine.

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Europlanet 2024 RI has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 871149.
Europlanet AISBL (Association Internationale Sans But Lucratif - 0800.634.634) is hosted by the Department of Planetary Atmospheres of the Royal Belgian Institute for Space Aeronomy (BIRA-IASB), Avenue Circulaire 3, B-1180 Brussels, Belgium.