User:Robertinventor/Simple animals could live in Martian brines - Extended Interview with planetary scientist Vlada Stamenković: Difference between revisions
User:Robertinventor/Simple animals could live in Martian brines - Extended Interview with planetary scientist Vlada Stamenković (edit)
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::'''VS''': Our work is calling for a complete revision for how we think about the potential for life on Mars, and the work oxygen can do, implying that if life ever existed on Mars it might have been breathing oxygen<!--Scientific American-->
[[File:Halichondria panicea.jpg|thumb|Halichondria panicea or the breadcrumb sponge- Stamenković et al's paper cites research by Mills et al using this sponge which showed it can survive with only 0.002 moles per cubic meter (0.064 mg per liter). This new research suggests that these concentrations can be achieved in {{w|Supercooling|supercooled}} brines on modern Mars in polar regions.]]
===Oxygen requirements for complex life such as sponges===
'''''(background information):''''' Saturated sea water is about 9 mg per liter at 20 °C ranging up to 11 mg per liter at 0 °C because cold water takes up the oxygen more readily.<!-- see for instance the two "Dissolved Oxygen" cites in the Background sources-->. The coldest saltiest brines on Mars don't quite reach these levels.
'''''(background information):''''' Stamenković et al cite a paper from 2014 that showed that some simple sponges can survive with only 0.002 {{w|Mole (unit)|moles}}per cubic meter (0.064 mg per liter) <!-- first page of Nature paper, "Meanwhile, whereas aerobic microbial life and simple animals need O<sub>2</sub> dissolved in liquids in sufficiently large concentrations to survive, recent experiments, observations and calculations have lowered the required limits of concentrations of dissolved O<sub>2</sub> for aerobic respiration to ~10−6 mol m−3 in microorganisms and to ~2 × 10−3 mol m−3 in sponges"-->. ▼
'''''Note:''''' The paper uses moles per cubic meter. Many other sources use miligrams per liter. To convert moles of oxygen per cubic meter to milligrams per litre multiply by 32.
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Some microbes that need oxygen can survive with as little as a millionth of a mole per cubic meter (0.000032 mg, or 32 nanograms per liter). In their model, they found that there can be enough oxygen for microbes throughout Mars, and enough for simple sponges in oases near the poles.
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For their calcium perchlorates map with {{w|Supercooling|supercooling}}, the lowest concentrations are around 25 millionths of a mole per cubic meter (0.008 mg per liter). For this brine regions poleward of about 67.5° to the north and about 72.5° to the south, could have oxygen concentrations high enough for simple sponges. Closer to the poles, concentrations could go higher, approaching levels typical of sea water on Earth, 0.2 moles per cubic meter (6.4 mg per liter), for calcium perchlorates. The brine that achieved the highest oxygen solubility is magnesium perchlorates. With this, oxygen concentrations could reach values as high as two moles per cubic meter (64 mg per liter<!-- atomic weight here http://ciaaw.org/oxygen.htm -->)<!--abstract of paper--> for the best case with supercooling.
On Earth, worms and clams that live in the muddy sea beds require 1 mg per liter, bottom feeders such as crabs and oysters 3 mg per liter, and spawning migratory fish 6 mg per liter, all
==Interview==
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