Re: [DIYbio] Re: I had idea on biospheres.

On Fri, Oct 26, 2012 at 8:10 PM, Mega <masterstorm123@gmail.com> wrote:
> Mars cyclers won't be realized by NASA very probably. They rather use the traditional approach.

Nobody can know for sure what NASA is going to do in 20 years. Check
out Mason Peck, NASA's current Chief Technologist. Nobody would accuse
him of lacking imagination or long-term commitment.

> Well, you say Mars is dry? Orbiter data say 6% of weight at curiosities place.

Citation please?

Your "6%" doesn't stand up very well, from recent instrumentation
readings taken BY Curiosity itself:

"The prediction based on previous measurements using the Mars Odyssey
orbiter was that the soil in Gale Crater would be around 6% water. But
the preliminary results from Curiosity show only a fraction of this,"
said Maxim Mokrousov (Russian Space Research Institute), the lead
designer of the instrument."

http://www.sciencedaily.com/releases/2012/09/120928085214.htm

What they had from orbit was mostly evidence of hydrogen. Well, guess
what: there's similar evidence of hydrogen on the moon, which is a
very dry place despite that. There's a reasonable theory that protons
in the solar wind can combine with oxygen dissociated from surface
oxides by radiation to produce hydroxyls and H2O. Nice, but it's never
going to amount to very much water -- mining it would be a little like
mining platinum. Solar protons probably reach the ground on Mars in
significant quantity. There's little atmosphere, and no magnetic
shield.

Most of the theories proposing a significant amount of *existing*
subsurface ice on Mars do not, as far as I know, subtract out possible
contributions from solar-proton interactions, but rather attribute all
the detected hydrogen to the possible presence of water deeper down.

Radar data is tantalizing, but unfortunately ambiguous, with very
indirect inferences and a heavy reliance on analogies to terrestrial
subsurface permafrost conditions, analogies that might not hold up:

"Radar detection of subsurface ice on Mars has been widely debated in
part because the
dielectric signature of ice, as deduced from the dielectric constant,
can be confused with dry-
silicate-rich materials."

http://www.agu.org/pubs/crossref/2011/2010JE003768.shtml

> Phoenix has found water.

I always had a big problem with that. Phoenix found evidence of water
ice by spectrographic measurements in soil in its immediate vicinity,
after the water had supposedly sublimated from some bulk samples (the
"dice cubes"), and after a landing that disturbed the site, allowing
for reactions and diffusion of reaction byproducts into soils.

Specifically: Phoenix did a powered landing with hydrazine thrusters.
Hydrazine reactions are very exothermic, potentially hot enough to
liberate oxygen from oxides in soil. Hydrazine reactions release a lot
of hydrogen. So there's a possible explanation for that relatively
pure frost layer they exposed (the "Snow White 1 + 2" evidence): a
thin layer of rapidly frozen steam captured underneath detritus thrown
up by the landing itself.

Then there are the "dice cubes" that seemed to sublimate away faster
than CO2 ice would explain. But, at least in the photos I've seen,
they seem to have been in continuous shadow, where it might have been
a lot colder than the surface temperature average that Phoenix could
register. The sampler didn't get to them until after the sublimation
-- of whatever it was that made them cuboid for a while. (Did they do
very focused IR readings around those "dice cubes" to make *sure* they
weren't CO2 ice? Did they measure the surface conductivity of what
those "dice" were sitting on, which might have provided a significant
heat-sink to help keep the CO2 frozen?)

NASA was, of course, very triumphalist about all this. They do good
science, I know. But sometimes it's all in how you say it. And saying,
"Um, sorry, but it's still ambiguous" as often as cold objectivity
might warrant in this case would make it harder to keep the Mars-probe
megabucks flowing.

> At the poles there is water.

No doubt. But the poles are not exactly a good place to set up a base
that relies on solar for heating and growing food.

> Of course, you would send a robot first. That harvests the water.

Which might or might not be there in sufficient quantity and
*availability* (which includes *meltability*) to make it worth lifting
into Mars orbit for return-trip CELSS and shielding. Or even for any
immediate life-support purpose.

Yes, there's a lot of water ice at the poles. But the poles are *very*
cold, which means that its ice is very cold; water ice has huge heat
capacity, which means your heat source had better be pretty strong.
Your robot will have a significant nuclear reactor. Curiosity's
plutonium-fueld MMRTG produces 2.8 W/kg (electrical output, not
radioisotope heat output -- conversion efficiency is under 10%). Since
it's a spacecraft component, it's super-optimized for low weight. An
exercise for you: with 2.8 W/kg from one those MMRTGs, starting with
Martian polar ice, at a mean temperature of about -160 deg C (and
buried under CO2 in winter) how long would it take to melt out a liter
of water? (I think the answer will kinda make you want to melt Martian
polar ice using the plutonium itself, straight, no chaser.)

When I say Mars is very dry, I don't mean just that it has a lot less
water than the Earth, per unit of surface area. I also mean that ice,
when cold enough, and with heating sources in short supply, might as
well be rock.

Regards,
Michael Turner
Project Persephone
1-25-33 Takadanobaba
Shinjuku-ku Tokyo 169-0075
(+81) 90-5203-8682
turner@projectpersephone.org
http://www.projectpersephone.org/

"Love does not consist in gazing at each other, but in looking outward
together in the same direction." -- Antoine de Saint-Exupéry

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