Experimental Investigation of the Atmosphere-Regolith Water Cycle on Present-Day Mars

The water content of the upper layers of the surface of Mars is not yet quantified. Laboratory simulations are the only feasible way to investigate this in a controlled way on Earth, and then compare it with remote and in situ observations of spacecrafts on Mars. Describing the processes that may in...

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Autores principales:	Abhilash Vakkada Ramachandran, María-Paz Zorzano, Javier Martín-Torres
Formato:	article
Lenguaje:	EN
Publicado:	MDPI AG 2021
Materias:	Mars pure liquid water water cycle simulation habitability planetary protection ISRU Chemical technology TP1-1185
Acceso en línea:	https://doaj.org/article/d9d239f49b0041629fc8e10d1bfb4abc
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spelling	oai:doaj.org-article:d9d239f49b0041629fc8e10d1bfb4abc2021-11-11T19:20:16ZExperimental Investigation of the Atmosphere-Regolith Water Cycle on Present-Day Mars10.3390/s212174211424-8220https://doaj.org/article/d9d239f49b0041629fc8e10d1bfb4abc2021-11-01T00:00:00Zhttps://www.mdpi.com/1424-8220/21/21/7421https://doaj.org/toc/1424-8220The water content of the upper layers of the surface of Mars is not yet quantified. Laboratory simulations are the only feasible way to investigate this in a controlled way on Earth, and then compare it with remote and in situ observations of spacecrafts on Mars. Describing the processes that may induce changes in the water content of the surface is critical to determine the present-day habitability of the Martian surface, to understand the atmospheric water cycle, and to estimate the efficiency of future water extraction procedures from the regolith for In Situ Resource Utilization (ISRU). This paper illustrates the application of the SpaceQ facility to simulate the near-surface water cycle under Martian conditions. Rover Environmental Monitoring Station (REMS) observations at Gale crater show a non-equilibrium situation in the atmospheric H<sub>2</sub>O volume mixing ratio (VMR) at night-time, and there is a decrease in the atmospheric water content by up to 15 g/m<sup>2</sup> within a few hours. This reduction suggests that the ground may act at night as a cold sink scavenging atmospheric water. Here, we use an experimental approach to investigate the thermodynamic and kinetics of water exchange between the atmosphere, a non-porous surface (LN<sub>2</sub>-chilled metal), various salts, Martian regolith simulant, and mixtures of salts and simulant within an environment which is close to saturation. We have conducted three experiments: the stability of pure liquid water around the vicinity of the triple point is studied in experiment 1, as well as observing the interchange of water between the atmosphere and the salts when the surface is saturated; in experiment 2, the salts were mixed with Mojave Martian Simulant (MMS) to observe changes in the texture of the regolith caused by the interaction with hydrates and liquid brines, and to quantify the potential of the Martian regolith to absorb and retain water; and experiment 3 investigates the evaporation of pure liquid water away from the triple point temperature when both the air and ground are at the same temperature and the relative humidity is near saturation. We show experimentally that frost can form spontaneously on a surface when saturation is reached and that, when the temperature is above 273.15 K (0 °C), this frost can transform into liquid water, which can persist for up to 3.5 to 4.5 h at Martian surface conditions. For comparison, we study the behavior of certain deliquescent salts that exist on the Martian surface, which can increase their mass between 32% and 85% by absorption of atmospheric water within a few hours. A mixture of these salts in a 10% concentration with simulant produces an aggregated granular structure with a water gain of approximately 18- to 50-wt%. Up to 53% of the atmospheric water was captured by the simulated ground, as pure liquid water, hydrate, or brine.Abhilash Vakkada RamachandranMaría-Paz ZorzanoJavier Martín-TorresMDPI AGarticleMarspure liquid waterwater cycle simulationhabitabilityplanetary protectionISRUChemical technologyTP1-1185ENSensors, Vol 21, Iss 7421, p 7421 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Mars pure liquid water water cycle simulation habitability planetary protection ISRU Chemical technology TP1-1185
spellingShingle	Mars pure liquid water water cycle simulation habitability planetary protection ISRU Chemical technology TP1-1185 Abhilash Vakkada Ramachandran María-Paz Zorzano Javier Martín-Torres Experimental Investigation of the Atmosphere-Regolith Water Cycle on Present-Day Mars
description	The water content of the upper layers of the surface of Mars is not yet quantified. Laboratory simulations are the only feasible way to investigate this in a controlled way on Earth, and then compare it with remote and in situ observations of spacecrafts on Mars. Describing the processes that may induce changes in the water content of the surface is critical to determine the present-day habitability of the Martian surface, to understand the atmospheric water cycle, and to estimate the efficiency of future water extraction procedures from the regolith for In Situ Resource Utilization (ISRU). This paper illustrates the application of the SpaceQ facility to simulate the near-surface water cycle under Martian conditions. Rover Environmental Monitoring Station (REMS) observations at Gale crater show a non-equilibrium situation in the atmospheric H<sub>2</sub>O volume mixing ratio (VMR) at night-time, and there is a decrease in the atmospheric water content by up to 15 g/m<sup>2</sup> within a few hours. This reduction suggests that the ground may act at night as a cold sink scavenging atmospheric water. Here, we use an experimental approach to investigate the thermodynamic and kinetics of water exchange between the atmosphere, a non-porous surface (LN<sub>2</sub>-chilled metal), various salts, Martian regolith simulant, and mixtures of salts and simulant within an environment which is close to saturation. We have conducted three experiments: the stability of pure liquid water around the vicinity of the triple point is studied in experiment 1, as well as observing the interchange of water between the atmosphere and the salts when the surface is saturated; in experiment 2, the salts were mixed with Mojave Martian Simulant (MMS) to observe changes in the texture of the regolith caused by the interaction with hydrates and liquid brines, and to quantify the potential of the Martian regolith to absorb and retain water; and experiment 3 investigates the evaporation of pure liquid water away from the triple point temperature when both the air and ground are at the same temperature and the relative humidity is near saturation. We show experimentally that frost can form spontaneously on a surface when saturation is reached and that, when the temperature is above 273.15 K (0 °C), this frost can transform into liquid water, which can persist for up to 3.5 to 4.5 h at Martian surface conditions. For comparison, we study the behavior of certain deliquescent salts that exist on the Martian surface, which can increase their mass between 32% and 85% by absorption of atmospheric water within a few hours. A mixture of these salts in a 10% concentration with simulant produces an aggregated granular structure with a water gain of approximately 18- to 50-wt%. Up to 53% of the atmospheric water was captured by the simulated ground, as pure liquid water, hydrate, or brine.
format	article
author	Abhilash Vakkada Ramachandran María-Paz Zorzano Javier Martín-Torres
author_facet	Abhilash Vakkada Ramachandran María-Paz Zorzano Javier Martín-Torres
author_sort	Abhilash Vakkada Ramachandran
title	Experimental Investigation of the Atmosphere-Regolith Water Cycle on Present-Day Mars
title_short	Experimental Investigation of the Atmosphere-Regolith Water Cycle on Present-Day Mars
title_full	Experimental Investigation of the Atmosphere-Regolith Water Cycle on Present-Day Mars
title_fullStr	Experimental Investigation of the Atmosphere-Regolith Water Cycle on Present-Day Mars
title_full_unstemmed	Experimental Investigation of the Atmosphere-Regolith Water Cycle on Present-Day Mars
title_sort	experimental investigation of the atmosphere-regolith water cycle on present-day mars
publisher	MDPI AG
publishDate	2021
url	https://doaj.org/article/d9d239f49b0041629fc8e10d1bfb4abc
work_keys_str_mv	AT abhilashvakkadaramachandran experimentalinvestigationoftheatmosphereregolithwatercycleonpresentdaymars AT mariapazzorzano experimentalinvestigationoftheatmosphereregolithwatercycleonpresentdaymars AT javiermartintorres experimentalinvestigationoftheatmosphereregolithwatercycleonpresentdaymars
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Experimental Investigation of the Atmosphere-Regolith Water Cycle on Present-Day Mars

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