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User:Robertinventor/Email-Interview-with Vlada follow up

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Hi Vlada, hope things have eased off for you since the publication in Nature, and I wonder if I can ask you a few more questions?

I plan to publish your interview soon. Still going through review at Wikinews. Our review process is rather thorough, and I will be doing my own blog and wiki entries once this is done.

Anway this review turned up a technical question I can't answer. For the main story, we solved it by just removing a number that we got confused by, but I am interested to know what the answer is.

So if you have time I wonder if you can resolve this for us, especially as I want to quote it in my longer article, also for my "Encyclopedia of Astrobiology" wiki, where I want to go into you research in some depth?

I also have a few more questions if you have time to answer them mainly on technical details. There are a fair number but for many the answers are probably simple. It's absolutely fine to give short answers. Or skip some of them.

As before, I would publish your responses, where it is appropriate, longer replies etc.

First the puzzling numbers:

  • This is about your figures 3a and 2a. The paper itself mentions a lower limit of 2.5 * 10-5 moles per cubic meter. But in Figure 2a neither the calcium nor the magnesium perchlorates bar stops at 2.5 indeed it looks more like 1.<something> for the lower limit.
    I wondered if the difference was due to atmospheric presesure, but the discrepancy is in the wrong direction because in the Southern uplands with the pressure less than 6.7 mbar, you'd expect the oxygen levels to be less if anything for the map than for figure 2a. Well, I'd have thought so anyway.
    So, what are we missing here?

And a question about the numbers in the abstract, case of confirming that I understood what it said:

  • In the abstract you talk about an upper limit of 2 moles per cubic meter. Is this for the magnesium perchlorates of figure 2a best estimate with supercooling?
    It also gives a lower limit of 2.5 * 10-6 moles per cubic meter. Is this for the Sodium perchlorates from figure 2?

I also wondered if the actual numbers numbers are available for public sharing?

  • Are the numbers corrsponding to Fig2 bars are available especially 2a? (Maybe they are in the supplementary information but I can't seem to find them)

Then there's a question about the warm water:

  • When you talked about warm water encountering the brines from below, I assumed you were talking about warmer water rising from subsurface geothermal hot spots and similar phenomena
    (hydrothermal vents, liquids from cave systems such as sulfur caves etc, ice fumaroles if they exist, rising vapour and warmth from the deep hydrosphere if it exists). Is that the sort of thing you had in mind. Or something more specific? Just wondered if you care to elaborate here

I'm also interested in mixes of salts for my longer article:

  • Have you investigated the idea of a mix of salts such as Phoenix found, with sodium, potassium, magnesium and calcium for the anions and perchlorates, chlorides and sulfates for the cations all mixed together(table 3 of [1])? What I wondered is can such a mix can have a higher oxygen concentration than any of the salts separately, as the freezing out process takes them to an optimal eutectic mixture in solution? Or is the effect of such a mixture too minute to be of interest?
    (I get the impression from the literature including that paper, that the depression of the eutectic below the optimal salt Magnesium perchlorate, is likely to be small, a fraction of a degree, so it is probably an ignorable effect unless the other factors in your calculation were significant- but I would like to be able to say that, rather than just guess it, if that is the case).
  • This is about the choice to map calcium perchlorate instead of magnesium perchlorate in the paper. I found a paper about an experiment that used a mix of salts simulating the Phoenix lander data. As they cooled it, then by -60 °C they ended up with magnesium perchlorate and just about everything else had precipitated out including the calciunm perchlorates[2].
    If that was typical of the polar regions it might suggest that magnesium perchlorate map would possibly even be the dominant scenario for Mars.
    Wondered what your thoughts are on that.
  • Did you do the Magnesium perchlorates map in detail? With that difference between 0.2 and 2 miles maximum per cubic meter, it would be interesting to know, e.g. what the extent is of the region for sponges, is it larger? And - is there then a significant region that has 0.2 moles per cubic meter? Or indeed 0.1 moles per cubic meter enough for bottom dwelling crabs on Earth?

Then I have a couple of questions about fresh water.

  • Question about methodology, is pure water optimal? In detail: from your figure S1 in the supplmentary information, and he following discussion, it seems that you started with the theoretical oxygen solubility in pure water, and the presence of salts reduced it by salting out factors. Have I understood the methodology correctly? So that the situation for pure water is optimal for oxygen solubility?
  • I have an additional question about Undercooled Liquid Interface water. Do you know if the same results apply for ULI thin films of water?
    Mohmann, whose research particularly interests me, says that these are biologically relevant nanolayers of fresh water that form down to -90 C (183.15 K) that are used in Antarctic ice by microbes[4]. Also, researchers have suggested they may occur on Mars[5].
  • Potential oxygen concentrations for pure water: from your figure S1 and from figure 1 in the paper, it would seem that at those temperatures, they could reach about 2 * 10-4 moles per cubic meter, and fresh water at 0 C. a little under 2 * 10-5 moles per cubic meter.
    So, just wanted to check, first are those figures correct? Also, are they (on best estimate assumptions) potential oxygen concentrations for fresh water on Mars, based on your research, or would that need more work?
  • Is the maximum for radiolysis going to be the same as for oxygen from the atmosphere? E.g. for fresh water at 0 C, 2 * 10-4 moles per cubic meter (or whatever the number is)
  • I know you haven't done the dynamical research yet - but - Is it possible to have a preliminary rough idea of how long it would take for oxygen to get into the water? Are we talking about minutes, or hours, days, or weeks for oxygen to ge into the water?
    For instance, the deliquescing salts that Curiosity found beneath its wheels as it drove over the sand dunes, form overnight and dry up during the day. I mean - can this be ruled out already or is it something needing research?
  • Similarly for pure water, could oxygen get into any fresh water that forms through ice melting briefly in the Hellas basin, or even melting of morning frosts?
    The background here is that Gilbert Levin once suggested in an interview that as the frosts observed by the Viking lander evaporate, a ground hugging water vapour layer may form in the morning and so permit minute traces of water to be briefly stable as the morning frosts melt, and they reported that Chris McKay when asked about it thought the idea had some merit. For their idea, with Chris McKay's comments on it see Can Liquid Water Exist on Present-Day Mars? As far as I know it is still a possibility.

Also a couple of general questions,

  • Have there been any more developments since I emailed you that we could mention? For instance progreses with exploring time dependent processes in detail?
  • Can you think of anything else you'd like to add?

If you have some time to reply it is greatly appreciated,

Cheers!

Robert

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