Need some high-falutin' biochemistry theory here

[BobGreenwade]

Setting aside temperature and breathing concerns, would a being from a cold ammonia-based lifeform (as such are described in Star Hero) be able to survive in our atmosphere?

[Cancer]

Temperature and breathing is a lot .... (Pressure also is something.) So are you asking, "Chill Earth down to the ammonia-life standard conditions, making no other changes, and would they die if put here anyway?"

My guess is yup, they'd die pretty fast. Free molecular oxygen is pretty nasty stuff. Very few substances with any pretense of chemical activity can withstand oxygen. And oxygen will be present as a gas in the atmosphere; the boiling point of O2 is way below the freezing point of ammonia.

Ammonia and water also are strongly mutually soluble, and the melting point of the mixture varies all over depending on relative concentrations. Spit ammonia on ice and lots of water will dissolve into that ammonia. Depending on how permeable the organism's membranes are to water-ammonia mixtures, that seems likely to cause real problems.

[BobGreenwade]

Thanks -- the solubility was the real issue I was wondering about.

The basic idea was to take some ammonia-based beings and let them colonize the temperature-appropriate areas of Antarctica. I was trying to figure out if they'd need anything other than breathing apparatus. I guess the answer is affirmative (though if you keep them out of direct contact with the ice, there really isn't much water).

[Cancer]

Hal Clement's Star Light used some of the unpredictable properties of ammonia-water mixtures as rationale for some of the background events. The story's really about communications breakdowns in and between two groups who aren't fully above-board with each other, though.

For Antarctica ... environment suits would be needed, I expect. Whether that means they have to be pressure-armor suits remains up to you.

[Bismark]

Antarctica would currently be a very BAD place to put such an organism (even given the favourable temperatures) unless it has serious sunscreen and free radical scavengers:

lack of ozone layer (and hence seriously increased solar radiation reaching the planetary surface) + oxygen in atmosphere = free atomic oxygen (= oxygen radicals :thumbdown ), peroxides (:thumbdown :thumbdown ) and superoxides (:eek: :eek: :eek: )

Ouch!

We (and other oxygen-tolerant organisms) have special enzymes (such as superoxide dismutase) to deal with these nasty by-products, but, if those enzymes are not present the results are - ahem! - terminal [anaerobic bacteria have no such enzymes and die at an impressive rate when exposed to oxygen].

I am currently unable to remember what effect photo-oxidation would have on the ammonia-based organism, but it is unlikely to be pleasant...

[Curufea]

Rusting to death :)

[BobGreenwade]

Okay, then, pressure-sensitive domes it is.... :)