#205 - David Whitehouse and Mars Lakes
This week we talk to David Whitehouse about his new book Space 2069. We also discuss the lakes on Mars and halophiles
The calculus of probabilities, when confined within just limits, ought to interest, in an equal degree, the mathematician, the experimentalist, and the statesman.
François Arago (26 February 1786 – 2 October 1853)
LAKES ON MARS
Childish Mars, totally annoyed with Venus trying to wrestle back the title of the possible life-bearing planet.
Way back on Podcast 91 we talked about how ESA’s Mars Express had detected liquid water hidden under planet’s south pole. Radar data hinted to a lake of liquid water buried under layers of ice and dust in the south polar region of Mars. July 2018, the MARSIS radar studies suggested a subglacial lake 1.5 km (0.93 mi) below the southern polar ice cap, and about 20 km (12 mi) wide, the first known stable body of water on Mars, based on 29 observations collected by Marsis between 2012 and 2015
Well MARSIS generated 134 radar profiles, gathered between 2010 and 2019, and an Italian led team of scientists has discovered three more subglacial lakes on Mars.
The size of the first lake found, still the largest, has been corrected to 30 km (19 mi) wide. It is surrounded by at least 3 smaller lakes, each a few kilometres wide
PAPER: Multiple subglacial water bodies below the south pole of Mars unveiled by new MARSIS data
Sebastian Emanuel Lauro, Elena Pettinelli et al (from the Roma Tre University)
Based on signal processing procedures usually applied to terrestrial polar ice sheets, such as in Canada and Greenland. Their results strengthen the claim of the detection of a liquid water body at Ultimi Scopuli and indicate the presence of other wet areas nearby.
The waters are shown to be most likely hypersaline perchlorate brines, Already known to form at Martian polar regions and thought to survive for an extended period of time on a geological scale at below-eutectic temperatures, substances that melts or solidifies at a single temperature that is lower than the melting point of any of the constituents.
So basically even underground there isn’t enough heat to keep the water liquid, so it almost certainly has lots of salts dissolved in the water to keep it liquid. Unlike table salt (Sodium Chloride) these salts are more likely to be magnesium and calcium perchlorates (chlorine bound to four oxygens), which are remarkable de-icers, going down to about -120C
There are hypersaline (super salty) lakes on Earth,
Definitions of how the names of lakes and water bodies based on saltiness
Freshwater (< 0.05%),
Brackish water (0.05–3%),
Saline water (3–5%), Brine (> 5% - 26%),
hypersaline over 35%
Although another scale for saline lake classification differentiates between:
subsaline: 0.5–3‰ (0.05-0.3%)
hyposaline: 3–20‰ (0.3-2%)
mesosaline: 20–50‰ (2-5%)
hypersaline: greater than 50‰ (5%)
In the Arctic, the Canadian Devon Ice Cap contains two subglacial lakes that are hypersaline. In Antarctica, there are larger hypersaline water bodies,
You can float in a Salt Lake, like the Dead Sea (34.2% salinity) and the Great Salt Lake Utah, (5–27% variable salinity).
The Dead Sea the world's deepest hypersaline lake, and the Araruama Lagoon in Brazil is the world's largest.,
The Gaet'ale Pond, located in the Danakil Depression in Afar, Ethiopia. The water of Gaet'ale Pond has a salinity of 43%, making it the saltiest water body on Earth.
This may be the salty level of the Mars Lakes, over 10 times saltier than the ocean. But really the scientists don’t know what salts and how salty, but it is likely to be salty as all bodies of water that stand still for long periods get salty as they slowly dissolve the rock up to the point they are saturated to the max.
Life is found even in very harsh conditions here on Earth. Life in Saline conditions are normally extremophiles called Halophiles (greek for Salt loving) mostly Archaea, (a kind of pre-Bacterial single-cell life form) but some bacterial Halophiles exist and even eukaryotic species, obviously not very complex ones, but more like algeas and fungus.
There have been at least three independent routes of evolution to become a Halophile, with different strategies to overcome the salt destroying osmosis effects.
Artemia is a ubiquitous genus of small halophilic crustaceans living in salt lakes, they have a unique salt gland.
The most complex animal is North Ronaldsay sheep in Orkney, Scotland, their only food source is seaweed with salt concentrations that would kill any other breed of sheep, Typical Scottish extreme diet.
But is this relevant to mars, all this above life works in the presence of oxygen they are aerobes, but we want autotrophic (make there own food) and chemolithotrophic (make energy from inorganic compounds) psychrotolerant (are able to do this in very cold conditions) and methanogens (probably breath out methane in doing so)
How about the 2015 paper The Effects of Perchlorates on the Permafrost Methanogens: Implication for Autotrophic Life on Mars
Viktoria Shcherbakova et al.
They isolated and described four strains of methanogenic archaea of Methanobacterium and Methanosarcina genera from samples of Pliocene and Holocene permafrost from Eastern Siberia. They studied the effect of sodium and magnesium perchlorates on the growth of permafrost and non permafrost methanogens, and present evidence that permafrost hydrogenotrophic methanogens are more resistant to the chaotropic agent found in Martian soil. In this paper, they study the effect of sodium and magnesium perchlorates on the growth of permafrost and non permafrost methanogens, and present evidence that permafrost hydrogenotrophic methanogens are more resistant to the chaotropic agent found in Martian soil. Furthermore, as shown in the studies strain M2T M. arcticum, probably can use perchlorate anion as an electron acceptor in anaerobic methane oxidation. Earth’s subzero subsurface environments are the best approximation of environments on Mars, which is most likely to harbour methanogens; thus, a biochemical understanding of these pathways is expected to provide a basis for designing experiments to detect autotrophic methane-producing life forms on Mars.!!!!
The fermentation of salty foods (such as soy sauce, Chinese fermented beans, salted cod, salted anchovies, sauerkraut, etc.) often involves halophiles
You can get Soda Lakes too, strongly alkaline side of neutrality, typically with a pH value between 9 and 12. They are characterized by high concentrations of carbonate salts, typically sodium carbonate (washing Soda), the Cynobacteria in these type of lakes make flamingoes go pink, like in Lake Nakuru. But even in Soda lakes life is very diverse!!!
Compared to freshwater ecosystems, life in soda lakes is often completely dominated by prokaryotes, i.e. bacteria and archaea, However, a rich diversity of eukaryotic algae, protists and fungi have also been encountered in many soda lakes. Multicellular animals such as crustaceans (notably the brine shrimp Artemia and the copepod Paradiaptomus Africanus) and fish (e.g. Alcolapia), are also found in many of the less extreme soda lakes
As ecosystems isolated from Earth's atmosphere, subglacial lakes are influenced by interactions between ice, water, sediments, and organisms. They contain active biological communities of extremophilic microbes that are adapted to cold, low-nutrient conditions and facilitate biogeochemical cycles independent of energy inputs from the sun.
According to the Martian equivalent of the Daily express an asteroid the size of a sports car has just “Buzzed” the red Planet, https://www.whereisroadster.com/charts/