The Waters of Mars

[Briar King]

Our understanding of how life can come to be is extremely arrogant honestly. It makes sense to us after all we are here based on this law, but till we get out to the stars we will not know the rules. Oh I would love it if peaceful aliens found us and we could travel the stars in our lifetimes.

[king of nowhere]

This might be germane to the discussion. Scroll down to the section on Alien biology, which lists possible protein analogues and solvents they could work with. This is extremely speculative, and well out of my expertise, so there may be significant issues with it, but the site has generally been accurate within my areas of expertise, so I feel comfortable recommending it.

 

Also, Kobold, I thought you might like the site. I spent a lot more hours than I like to think about down the rabbit hole on that site. Worse than TV Tropes for me. Pretty much everything you need for true-to-modern-physics science fiction.

I checked that, and it's quite interesting.

Now, my knowledge of space in general comes mostly from reading nasa/esa announcements, wikipedia, and other stuff like that. I am quite knowledgeable, but I am not a specialist in the field. And from what I know, those parts are correct.

My knowledge of the chemistry of life instead comes from doing a PhD on it, therefore I think I am better qualified to judge that.

Lenghtly chemical discussion ahead, read only if interested.

And that part did not satisfy me. On some things I think it was too open to possibilities; fluorosilicones at high temperature, for example, could make some complex molecules, but definitely not differentiated enough for life. I'd also drop the fluorocarbons in molten sulfur, they may be stable, but most other functional groups are not. And I'd drop liquid hydrogen as an environment; too cold, everything would be frozen solid.

On the other hand, in other cases it was too strict in making assumptions. For example,

Polar liquids will not dissolve non-polar substances and vice versa (oil and water don't mix). Proteins are polar, so they won't dissolve in liquid methane.

That's plain wrong. The backbone of a protein is polar, but many aminoacids have nonpolar side chains, and a protein can fold to expose those to the exterior while keeping the polar parts inside. In fact, there are many proteins that dissolve in nonpolar environments and not in water: the interior of the cell membrane is strongly nonpolar, but there are plenty of proteins designed to go just there, and they do it. Therefore, "proteins in liquid methane" is a possibility; in fact, it is much more likely than fluorosilicones. Or also

Proteins in Liquid Ammonia: Because ammonia is hydrogenated nitrogen, the proteins will have more nitrogen than oxygen in their make up.

iis injustified. Life can get trace elements if it needs it. It would be like saying that since seawater contains more sodium than potassium, then sea life will contain more sodium; which is wrong, because the cells have the sodium/potassium pumps to keep the balance. There is nothing forbidding ammonia-based life to use more oxygen than nitrogen. Especially the assumption that it will consume carbon dioxide and produce oxygen. Or that silicon-based life will breath oxygen and release silicon dioxide. There is absolutely no need for that. On our planet, life learned to use solar power to produce glucose. oxygen was merely a byproduct of it, a toxic one (those first photosyntetic bacteria changed the atmosphere and caused the extinction of most life forms), but eventually life learned to use that too. I see no reason why alien life must breath oxygen. Although oxygen is ideal, because it's termodinamically highly reactive (you can get a lot of energy out of its reactions) but kinetically very stable (it won't hurt you unless it's activated). We live by harnessing the chemical energy of combustions, we get the oxydant agent from air and the reducing agent from food, but it doesn't have to be that way. We could do the reverse, getting the reducing agent from air, breathing hydrogen. We could get both from solid food, for example by eating perchlorate salts that may be excreted by plants as byproducts of whatever weird reaction they do in place of photosynthesis.

So, whoever wrote that got too optimistic about imagining life made of different building blocks, but he was too conservative by imagining that some of the processes should be similar.

 

 

Anyway, all that discussion made me forget the main thing i was wondering about that water: namely, where does it come from?

Yes, I know there' plenty of ice underground on mars, but those rivulets are on the slopes of moutains, and the water is flowing downhill. So it stand to reason that after four billion years, whatever ice was present underground on the mountain should have run out. There is some process that is resupplying that underground ice. Mars is too dry for rain, but can the scant water in its atmosphere condense on the ground? is it some kind of distillation process, where the water evaporates from the plain, freezes in the colder mountains, then melts in the summer and flows to the plains where it evaporates again? I suppose that's the most likely explanation; ann underground water system would have beeen much cooler, but less likely with our present data.