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

On Sat, Oct 27, 2012 at 8:35 PM, Mega <masterstorm123@gmail.com> wrote:
>> Now, starting with ice at around -160 deg K, .... or
>> am I the only one who's going to look up numbers and do arithmetic?
>>
>
> Have I ever said we should melt -160°C cold water?

You said the poles have lots of water. Why bother saying that, in this
context, unless to imply extraction was practical?

> That's wastement of energy. On the poles it's too cold, too.

So you agree with what I said, over and over, in my last message, but
without acknowledging that I said it over and over?

> Show me the source that says there's no water ice at the equator.

Show me the sources that assert, as unequivocally as YOU do, that
there IS equatorial water ice in concentrations worth mining. The only
reports that come close to your level of certainty are the ones I
already talked about in my last message -- reports I regard with some
skepticism. Don't just repeat yourself. Address that skepticism. Tell
me why I'm wrong to be concerned.

> http://www.space.com/10704-mars-water-ice-equator.html

Which says, among other things:

".... researchers could not rule out the possibility their findings
might reflect fluffy, dusty or loosely packed material that holds only
a small amount of ice."

Which would be consistent with the White Mars theory

http://mars.jpl.nasa.gov/mgs/sci/fifthconf99/6001.pdf

which proposes that much of what seems to be water-flow evidence is
actually CO2 flow of various kinds.

The article you link also says that the evidence is not conclusive and ....

"We must rely on additional satellite data and modeling studies"

-- because the evidence has other explanations, and because current
modeling suggests there shouldn't be such significant ice deposits
anyway.

You said there was 6% ice previously measured from orbit in
Curiosity's vicinity -- even though that was only indirect evidence
for which there are other explanations. Now that Curiosity's actually
IN that area, it's not finding water ice remotely approaching 6%. This
lends weight to the alternative explanations, not just in that area,
but in all other areas on Mars where similarly derived evidence has
been used to argue for significant water ice concentrations.

> By the way, I assume there are underground caves (from volcanic origin) like
> on Earth (Mars is a terrestrial planet). There is much pressure and heat
> from Mars' interior. Water would be liquid there. Of course, one would have
> to drill several hunders of meters which still is utopical.

OR there are easily accessed lava tubes where significant frost
precipitation of outgassed magmatic H2O might reasonably still be
intact. There's no evidence yet for that, however. If such evidence
emerges, it strengthens the case for using lava tubes instead of
surface habitats: maybe people and robots won't have to stripmine
their water on the surface, with all the problems of radiation and
dust mitigation that go with being on the surface. Maybe they'll be
able to just scrape it off cave walls.

> Get it from the Equator, where in summer you have moderate temperatures.

IF it's there in significant quantities. I happen to think the jury's
still out. Recent Curiosity results aren't encouraging.

> Don't get all the water you need on Mars, but recycle at 90-95% efficiency.

CELSS units already designed retain water at far higher efficiencies.
If you do a little math, you'll see that such efficiencies will be
important just to get to and from Mars. If you lose 5%-10% of a crew's
water requirements daily, the amount of water you need to take along,
just to make sure you have enough at the end, is radically increased.
More mass = more expense.

Robert Zubrin seems to accept water-recycling efficiencies in the low
90% range, for a surface base, in exchange for higher reliability

http://www.marsjournal.org/contents/2006/0005/files/rapp_mars_2006_0005.pdf

but Zubrin's risk perceptions are notoriously different from those of
most Mars mission planners. He bases survival and return-trips on ISRU
scenarios that, in the case of water, might not be realistic. If
you've got a base that can only keep 90% of its water on each cycle,
and can't mine ice fast enough because the ores turn out to be much
thinner than first thought, it's going to die of thirst.

> So you just to get 5-10% of the needed water.

Or hell, you just wave your hands, and water appears.

> As I have read, the shileding of the plutonium was quite exaggeraeted.

Don't you mean "conservatively engineered"?

> And you have a reliable rocket In any case

Rocket launch failures rates have never fallen much below 3% even for
Soyuz-U, which might be the current world-beater. It sounds like
you're willing to take a 3% chance of launch failure, on every launch
attempt for every RTG-powered mission, with perhaps up to 20,000 extra
cancer cases globally if the plutonium ends up scattered in the
atmosphere. No thanks. I'll take the extra RTG shielding. So will
everybody else on Earth. Paying that price buys the added range RTGs
get you in space. RTGs are essential for outer-planet missions.
Cassini is an example of a jaw-droppingly great mission that just had
to use them. Significant Mars missions -- Curiosity-scale and above --
are probably impossible without them.

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

> --
> -- You received this message because you are subscribed to the Google Groups
> DIYbio group. To post to this group, send email to diybio@googlegroups.com.
> To unsubscribe from this group, send email to
> diybio+unsubscribe@googlegroups.com. For more options, visit this group at
> https://groups.google.com/d/forum/diybio?hl=en
> Learn more at www.diybio.org
> ---
> You received this message because you are subscribed to the Google Groups
> "DIYbio" group.
> To post to this group, send email to diybio@googlegroups.com.
> To unsubscribe from this group, send email to
> diybio+unsubscribe@googlegroups.com.
> Visit this group at http://groups.google.com/group/diybio?hl=en.
> To view this discussion on the web visit
> https://groups.google.com/d/msg/diybio/-/4FsEWSNRpXcJ.
>
> For more options, visit https://groups.google.com/groups/opt_out.
>
>

--
-- You received this message because you are subscribed to the Google Groups DIYbio group. To post to this group, send email to diybio@googlegroups.com. To unsubscribe from this group, send email to diybio+unsubscribe@googlegroups.com. For more options, visit this group at https://groups.google.com/d/forum/diybio?hl=en
Learn more at www.diybio.org
---
You received this message because you are subscribed to the Google Groups "DIYbio" group.
To post to this group, send email to diybio@googlegroups.com.
To unsubscribe from this group, send email to diybio+unsubscribe@googlegroups.com.
Visit this group at http://groups.google.com/group/diybio?hl=en.
For more options, visit https://groups.google.com/groups/opt_out.