Mars habitability analogue environments on Earth
[1] A few places on Earth, such as the hyper-arid core of the high Atacama Desert and the McMurdo Dry Valleys in Antarctica approach the dryness of current Mars surface conditions.
These include ice caves, the icy fumaroles of Mount Erebus, hot springs, or the sulfur rich mineral deposits of the Rio Tinto region in Spain.
Laboratory simulations show that whenever multiple lethal factors are combined, the survival rates plummet quickly.
[19][20][21] It is the current testing site for the Atacama Rover Astrobiology Drilling Studies (ARADS) project to improve technology and strategies for life detection on Mars.
It was found through a systematic search for drier regions than Yungay in the Atacama Desert, using relative humidity data loggers set up from 2008 to 2012, with the results published in 2015.
There is snowdrift and limited melting around the edges and occasionally in the central region, but for the most part, moisture is only found as thin films of brine around permafrost structures.
This unusual flow of melt water from below the glacier gives scientists access to an environment they could otherwise only explore by drilling (which would also risk contaminating it).
[35][36] According to geomicrobiologist Jill Mikucki at the University of Tennessee, water samples from Blood Falls contained at least 17 different types of microbes and almost no oxygen.
[35] An explanation may be that the microbes use sulfate as a catalyst to respire with ferric ions and metabolize the trace levels of organic matter trapped with them.
[35] This process is of astrobiological importance as an analogue for environments below the Glaciers on Mars, if there is any liquid water there, for instance through hydrothermal melting (though none such has been discovered yet).
Exploration protocols should also assume that the subglacial aquatic environments contain living organisms, and precautions should be adopted to prevent any permanent alteration of the biology (including introduction of alien species) or habitat properties of these environments.28.
As a provisional guideline for general cleanliness, these objects should not contain more microbes than are present in an equivalent volume of the ice that is being drilled through to reach the subglacial environment.
It is designed for autonomous navigation to avoid obstacles such as cavities and embedded meteorites, so that it can be deployed remotely on Encladus.
This, combined with the cold and dryness conditions make it an interesting analogue of the Martian salts and salty regolith.
An expedition found eight strains of Haloarchaea inhabiting the salts, similar to some species of Virgibacillus, Oceanobacillus, Halobacillus, and Ter-ribacillus.
Mineralogy of the three springs is dominated by halite (NaCl), calcite (CaCO3), gypsum (CaSO4·2 H2O), thenardite (Na2SO4), mirabilite (Na2SO4·10H2O), and elemental sulfur (S°).
[49] This is another Mars analogue habitat in Axel Heiberg Island close to Colour Peak and Gypsum Hill.
The frozen soil and permafrost hosts many microbial communities that are tolerant of anoxic, acid, saline and cold conditions.
[1] "A martian soil survey in the Meridiani Planum region found minerals indicative of saline acidic brines.
This site comprises a terrestrial analogue for these environments and hosts microbes capable of survival under these Mars-like conditions"[1]Rio Tinto is the largest known sulfide deposit in the world, and it is located in the Iberian Pyrite Belt.
This area is rich in iron and sulfur minerals such as Much of the water on Mars is permanently frozen, mixed with the rocks.
[53] The ice caves near the summit of Mount Erebus in Antarctica, are associated with fumaroles in a polar alpine environments starved in organics and with oxygenated hydrothermal circulation in highly reducing host rock.
They also have a wide range of halophilic organisms, in all the three Kingdoms of life (Archaea, Bacteria and Eukaryota), in the surface and near subsurface.
[67] With the abundance of algae and bacteria, in alkaline hypersaline conditions, they are of astrobiological interest for both past and present life on Mars.
This is named after Meridiani Planum where Opportunity rover found crystal molds in sulfate deposits (Vugs) which are thought to be remains of this mineral which have since been dissolved or dehydrated.
[69][70] Another example is Spotted Lake, which shows a wide variety of minerals, most of them sulfates, with sodium, magnesium and calcium as cations.
[72][73][74] Sulfates (for instance of sodium, magnesium and calcium) are also common in other continental evaporates (such as the salars of the Atacama Desert), as distinct from salt beds associated with marine deposits which tend to consist mainly of halites (chlorides).
In the case of Mars, the depth needed for geothermal melting of the basal area of a sheet of ice is 4-6 kilometers.
When they applied their model to Mars, they showed that a liquid layer, once melted (initially open to the surface of the ice), could remain stable at any depth over 600 meters even in absence of extra geothermal heating.
These conditions occur in the high mountains of Antarctica, where lichens grow at altitudes up to 2,000 meters with no liquid water, just snow and ice.
4 ·11 H
2 O . Evidence from orbital measurements show that this is the phase of Magnesium sulfate which would be in equilibrium with the ice in the Martian polar and sub polar regions [ 63 ] It also occurs on the Earth, for instance in Basque Lake 2 in Western Columbia, which may give an analogue for Mars habitats.
