halogen - 2-6-2006 at 13:06
Xenobiology!
Inspired by the extremophile thread.
What kinds of life might exist on a silicon dioxide rich planet with a high concentration of fluorine in the atmosphere.
What if the principle solvent was NH3 and not H2O?
N-P chains instead of C-C
neutrino - 2-6-2006 at 15:06
Not much would survive with a fluorine atmosphere. SiO<sub>2</sub> would react with the fluorine (catalyzed by any protons that are
around) to form SiF<sub>4</sub>, as would ammonia (forming NF<sub>3</sub>
. I doubt N-P chains would be stable enough to survive in this atmosphere either.
JustMe - 2-6-2006 at 18:53
Well, that seems a little too extreme as there are hardly any processes that would lead to production of free fluorine (well, the same can be said of
oxygen as it is derived mostly organically with the help of sunlight, but still... fluorine?)
To be more realistic, I do feel that ammonia oceans are possible on a planetary scale at room temperature (high enough for life processes), and
although not as good a solvent, carbon dioxide. Why? Venus, for one. About the same gravitation as Earth at yet 100 times the pressure, mostly carbon
dioxide. Cool it off (well, a LOT) and the carbon dioxide would liquify. And if the pressure were only a bit higher than we have on Earth, ammonia
would be liquid.
So I don't think you need a high gravity planet to have other liquid environments condusive to life. I admit to a carbon bias, but do not to a water
bias.
Many years ago I did a science fair project in which the premise asked if a high chlorine environment would lead to chlorine analogs of hydrocarbons
by the same process/theory of the time of electrical storms creating amino acids. Long story short, came to the conclusion that while some interesting
chemisty would occur, that the hydrogen bond was really crucial to life processes and chlorine doesn't bond that way readily. But who knows, in a
universe of near infinite combinations, maybe so!
From a purely sci-fi point of view, I liked the Star Trek Next Generation episode in which life took the form of Gallium Nitride crystals in a salty
environment. So who is to say?
But I don't see any life process splitting out fluorine! (Neat concept, though).
End of musings.
Jome - 3-6-2006 at 05:30
As stated before free fluorine would react both with all common rock types and with the all-abundant hydrogen oxide.
But fluorine compounds like CFCs and SF6 has been proposed as a means to heat up a planet like Mars by greenhouse effect, making it suitable for life.
Perhaps one could design the biosphere to involve fluorine, so that the CFCs/SF6 would not be depleted. Something like:
Fluoride ions + sulfate -->SF6, all done by plants which is then broken down by the suns UV-radiation (halflife several decades), fluorine
returning to the surface as fluoride ions, sulfur as SO2-->H2SO4 and we're back.
Extensive genetic experiments would have to be done to modify earth life to survive in an environment with at lot of F-.
Other ideas?
Make life that live in the vacuum of space, living of sunlight and chewing asteroid.
halogen - 27-6-2006 at 21:54
You people need to be demanded to stop speculating about this in a thread about extremophiles and now this!?