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

On Sun, Oct 28, 2012 at 3:03 AM, Mega <masterstorm123@gmail.com> wrote:

[Michael Turner]
> It sounds like
> you're willing to take a 3% chance of launch failure, on every launch
> attempt for every RTG-powered mission

[Mega]
> "On every launch ... for every RTG .... " That sounds like there were much.
> There haven't been, and there won't be.

26 missions by the U.S. alone is "not much"? 45 RTGs sent to space so
far (by the U.S. alone) is "not much"?

"Radioisotope power has been used on 8 Earth orbiting missions, 8
missions travelling to each of the outer planets as well as each of
Apollo missions following 11 to Earth's moon. Some of the outer Solar
System missions are the Pioneer, Voyager, Ulyssess, Galileo, Cassini
and Pluto New Horizons missions. The RTGs on Voyager 1 and 2 have been
operating since 1977. Similar RHUs which provide heat to critical
electronics have been used on Apollo 11 as well as the first 2
generations of Mars rovers.[7] In total, over the last four decades,
26 missions and 45 RTGs have been launched in the United States."

http://en.wikipedia.org/wiki/Multi-Mission_Radioisotope_Thermoelectric_Generator

The total undoubtedly goes up quite a bit more when you include the
contributions of other nations, especially since Russia was a leader
in RTGs.

> Unfortunately, Obama has made the
> energy-departement stop the production of RTG by not providing the money
> needed.

You are, as usual, mistaken. In this case, you're unusually mistaken.
Congress failed to appropriate funds for re-initiating domestic
production of the main RTG fuel, Pu-238. Congress, if you'll recall,
is dominated by the GOP in the House, and can filibuster anything in
the Senate.

http://www.spacesafetymagazine.com/2012/01/09/pu-238-production-risk/

NASA, if you'll recall, is run by Charles Bolden -- an Obama
appointee. NASA has actually urged the resumption of Pu-238
production.

http://www.spacesafetymagazine.com/2011/09/27/nasa-urges-resuming-plutonium-238-production/

This most recent "fact" of yours is only 180 degrees off from the truth.

> And yeah, for high-value missions you have to take som risk. You said you're
> familiar with the rocket equation.
>
> The shielding adds mass, which has to be taken into orbit,
[snip]

I really don't need things like this explained to me.

> If the RTG hits, it will more than 70% likely hit water.

What you hand-wave aside: that the problematic event won't involve
disintegration of the payload within the atmosphere. Rockets do fail
explosively at times. Analyses of RTG disintegration risk base their
estimates of health almost entirely on such events:

http://www.fas.org/nuke/space/pu-ulysses.pdf

In their view, hitting land doesn't pose much risk:

"Only if an RTG hits something as hard as granite on its plunge back
to Earth, or if it is hit by a shard from an explosion of a solid
rocket booster, does it have any chance of fracturing."

The percentage of the Earth's surface that's exposed granite is
minuscule -- much smaller than the percentage of rocket boosters that
blow up in the atmosphere.

> For RTG-powered missions each 5 years you can risk low shielding, if you in
> return take the most reliable rocket. But that's just my opinion.

We've had a lot of your opinions here. They are very seldom backed up
by citations, and never backed by calculations.

> It seems to me kind of like a belief - thing. You can say, you believe Mars
> is very very low in water at the equator, I say it's *relatively* much
> there. (In the sense of a bit is there. )

You now say "a bit is there". I said "Mars is very dry." Given that
there are some H2O molecules in almost everything that we don't
hesitate to call "very dry", there's no direct contradiction here --
except with numerous assertions YOU have flatly made on this thread.

> Yeah, Curiosity could have just landed in a dryer region.

That's the current hope. And it's fine to hope.

Not so cool: stating unproven hypotheses as fact. Especially when the
truth (as in the case of your claims of an end to space-mission RTG
production on orders from the Obama administration) is actually the
OPPOSITE of what you're saying.

Curiosity is in Gale Crater, which was chosen because of the higher
likelihood of past and present water.

http://en.wikipedia.org/wiki/Gale_(crater)

Current sampling in a relatively high-probability region is now coming
up empty-handed. It's far drier than one optimistic hypothesis plus
some ambiguous orbital readings would suggest (that 6%). It's about as
dry as the state of the art in Mars modeling suggests. This is not
exactly grounds for greater hope in anything except those models. How
science proceeds: by comparing model predictions with evidence.

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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