Re: Planet Densities
James Rogers (jamesr@best.com)
Wed, 13 Nov 1996 16:20:43 -0800
At 10:32 PM 11/12/96 -0500, you wrote:
>James Rogers wrote:
>> Ice isn't conducive to life and
>> very hot water/steam is extremely destructive to organic compounds.
>>
>
>Actually, this is not true. Organic compunds used to living at our
>pressure and temp are very sensitive, but only because of the elements
>their prtiens use to bind themselves together with. A protein molecule
>is like a messed up ball of yarn, with energy bonds wherever the strands
>cross. TO do its work as a protein, it must have a certain amount of
>springiness to it to stay in solution, and must be able to be broken
>apart with little energy input. Too much energy input, and the molecule
>will break apart and precipitate out of solution, which is how egg
>whites get white when you boil them. Using different elements at the
>energy bond points than is used for normal temp organisms allows for
>much higher temperature tolerance, as the bonds are much tighter, and
>require higher energy input to break them apart, however this makes for
>a very tightly bound molecule that only does its chemical work at a
>higher temperature. For example, a common protein in bacteria which uses
>iron in its makeup, has a corollary protein in hyperthermophilic
>bacteria (bacteria that can live above boiling) that uses tungsten
>instead.
>
>These bacteria have been recovered from deep sea volcanic vents, deep
>oil wells, and deep geothermal systems, and have exhibitied preference
>for temperatures above 180 degrees F (about 90 C) up to as much as 275 F
>(about 130 C). As more varieties are recovered, the upper limit seems to
>creep higher, especially as specemins are recovered from deeper and
>deeper sites.
>
True, there are some organisms who can thrive in this environment, but their
makeup is significantly different than surface dwelling organisms. The
pressure where they live allows liquid water reactions to continue to occur.
Even then, there is a soft limit somewhere around 150-170 C for most
organics. The absolute hard limit on any planet is somewhere around 375 C
since this is where water goes supercritical, although very few organics
would survive even to this point (except maybe some halides and a few
proteins). Cells require a pretty broad spectrum of organic compounds to
operate, and the number of options decreases rapidly as the temperature
increases.
Sub-zero lifeforms are not that unusual, although it is unusual for higher
lifeforms to exist in these environments. In an environment that is
perpetually subzero, I would expect to find either very primitive nervous
systems, or nervous systems that operated in a different fashion than ours.
The nervous systems found on this planet don't operate well in cold
environments, since they rely on ion/molecule transport. This is why
mammals found in cold climates on this planet require immense quantities of
insulation.
-James Rogers
jamesr@best.com