User:Robertinventor/Simple animals could live in Martian brines - Extended Interview with planetary scientist Vlada Stamenković: Difference between revisions

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[[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.]]
[[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.]]
Since cold brines take up more oxygen, it's no surprise that they found the highest concentrations in polar regions. That's where they found there would be enough for simple sponges.
Since cold brines take up more oxygen, it's no surprise that they found the highest concentrations in polar regions. That's where it reaches the levels high enough for simple sponges.
[[File:PIA22546-Mars-AnnualCO2ice-N&SPoles-20180806.gif|thumb|Extents of north (left) and south (right) polar CO<sub>2</sub> ice during a Martian year. These are not photos, rather they are based on infrared data from two instruments that can study the poles even at times of complete darkness. The dry ice here reaches temperature of around -125&nbsp;°C, well below its sublimation temperature of -78.5&nbsp;°C, which gives an idea of how cold the Martian poles get in winter. In Vlada Stamenković et al's model the highest oxygen concentrations occur at temperatures down to -123 to -133&nbsp;°C.]]
[[File:PIA22546-Mars-AnnualCO2ice-N&SPoles-20180806.gif|thumb|Extents of north (left) and south (right) polar CO<sub>2</sub> ice during a Martian year. These are not photos, rather they are based on infrared data from two instruments that can study the poles even at times of complete darkness. The dry ice here reaches temperature of around -125&nbsp;°C, well below its sublimation temperature of -78.5&nbsp;°C, which gives an idea of how cold the Martian poles get in winter. In Vlada Stamenković et al's model the highest oxygen concentrations occur at temperatures down to -123 to -133&nbsp;°C.]]


They 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"-->.
They base this on another 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"-->.


They paid particular attention to two brines, magnesium and calcium perchlorates, common on Mars. If they start off liquid, they can be {{w|Supercooling|supercooled}} to temperatures as low as -123 to -133&nbsp;°C still liquid, and then transform to a glassy state in simulation experiments. They can be supercooled like this even when mixed with the soil of Mars (regolith). It's at these very low temperatures that the optimal oxygen concentrations can be reached.
They looked closely at two brines, magnesium and calcium perchlorate, common on Mars. Previous papers show that starting with these brines in a warmer liquid state in Mars simulation experiments, they can be {{w|Supercooling|supercooled}} to temperatures as low as -123 to -133&nbsp;°C while remaining liquid, before they transform to a glassy state. This supercooling works even when the salty brines are mixed with the martian soil (regolith). It's at these very low temperatures that they will reach the optimal oxygen concentrations.


They found that supercooled calcium perchlorate brines can reach oxygen concentrations high enough for simple sponges in regions poleward of about 67.5° to the north and about 72.5° to the south. Closer to the poles, oxygen concentrations could go higher, reaching 0.2 moles per cubic meter (6.4 mg per liter). This is not far off levels typical of sea water on Earth.
The oxygen concentrations in calcium perchlorate brines got high enough for simple sponges in regions poleward of about 67.5° to the north and about 72.5° to the south. As you get closer to the poles, oxygen concentrations could go higher, reaching 0.2 moles per cubic meter (6.4 mg per liter). This is not far off levels typical of sea water on Earth.


'''''(background information):''''' on Earth, the most oxygen you can get in warm sea water is about 0.28 moles per cubic meter (9 mg per liter) at 20&nbsp;°C which increasess to 0.34 moles per cubic meter (11 mg per liter) at 0&nbsp;°C because cold water takes up the oxygen more readily.<!-- see for instance the two "Dissolved Oxygen" cites in the Background sources-->.
'''''(background information):''''' on Earth, the most oxygen you can get in warm sea water is about 0.28 moles per cubic meter (9 mg per liter) at 20&nbsp;°C which increasess to 0.34 moles per cubic meter (11 mg per liter) at 0&nbsp;°C because cold water takes up the oxygen more readily.<!-- see for instance the two "Dissolved Oxygen" cites in the Background sources-->.
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