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Sedna, space probes?, colonies? what's next?



 
 
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  #21  
Old March 18th 04, 04:13 AM
Sander Vesik
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Default Sedna, space probes?, colonies? what's next?

Dez Akin wrote:
"Mike Combs" wrote in message ...
"Marvin" wrote in message
...

You are advocating *SOLAR* power, out that far?


snip

You dont need large mirrors, you need un-be-fooking-lievably giganic
hugenourmous mudderfookahs of mirrors.


All very true. But in 0-G, the mirrors needn't be anything more substantial
than aluminized mylar stretched over bailing wire.

Gerard O'Neill got curious how far a space habitat could range from the sun
simply by increasing mirror size. He decided a good stopping point was when
the mirror came to mass as much as the rest of the habitat. The calculation
came out as 10x the distance of Pluto.

I just read that Sedna is currently about 3x the distance of Pluto (yes, I
know, it gets out a lot farther).


Theres nothing wrong with nuclear. By the time we start considering
space habitats this far out, nuclear fusion might even be viable, but
we can build molten salt fission plants now for fueling a huge colony
for at least a couple of centuries.


Yes, but you can't build a huge colony even in Earth or Moon orbit -
never mind somewhere far away - nor move it as things stand. And the
cause for that is launch costs, something that is not noticably helped
by nuclear reactors.

--
Sander

+++ Out of cheese error +++
  #22  
Old March 18th 04, 10:36 AM
Uddo Graaf
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Default Sedna, space probes?, colonies? what's next?


"Sander Vesik" wrote in message
...
Uddo Graaf wrote:

"TKalbfus" wrote in message
...
I find it interesting that Sedna was discovered near its closest point

in
its
10,500 year orbit around the Sun. What are the chances of that

happening?
If
you only consider the planet Sedna, the chances of discovering it

while it
is
near is closest point to the Sun are very small. Sedna spends most of

its
time
further away, this leads to the question how many other "Sedna's" are

there?
What if we looked for a 10th planet 1000 years ago with the same

technology we
have today? Would we find another Sedna-like planet nearing its

closest
point
to the sun. Sedna will spend 150 closer to the Sun than from where we
discovered it. statistically this leaves room for about 60 planets in

10,000
year orbits around the sun. all those planets are potential colonies

for
future
colonists. The ones further away will be harder to find, but I'm sure

we
can
eventually discover them.


Colonies that far away from the Sun? Unlikely. Mankind can multiply like
rabbits and it would still take at least 300 years to fill up the inner
planets and moons. Sedna or its denizen's aren't likely candidates for
colonization and when they are, mankind will probably have developed FTL
(faster than light) propulsion and reach for planets beyond our solar
system.


Even with FTL, colonising Oort cloud may be easier than plants around
far-away stars. At 4c it still takes 9months for a one-way trip to
Alpha Cenaturi - and much longer for other stars. FTL - unless it
is high multiples of lightspeed - only makes interstellar travel and
colonisation slightly easier. You will pobably still need generation
ships - just the number of generations born on-ship will be lower.


Mostly colonization will be done by 'system hopping' and will therefore be
doable. Someone calculated once that if we started now, we could colonize
the entire Galaxy in 3000 years.


  #23  
Old March 18th 04, 03:48 PM
Ian Stirling
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Default Sedna, space probes?, colonies? what's next?

John Savard wrote:
On Wed, 17 Mar 2004 16:50:48 +0100, "Uddo Graaf"
wrote, in part:

Colonies that far away from the Sun? Unlikely. Mankind can multiply like
rabbits and it would still take at least 300 years to fill up the inner
planets and moons.


Earth is already full, and not more than the tiniest fraction of its


Debatable.
Stick copies of biosphere II all over the world, and you end up with
well over 10 times the population.
  #24  
Old March 18th 04, 03:55 PM
Paul Blay
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Default Sedna, space probes?, colonies? what's next?

"Ian Stirling" wrote ...
Debatable.
Stick copies of biosphere II all over the world, and you end up with
well over 10 times the population.


Better hope they work a bit better than the first biosphere II then. ;-)
  #26  
Old March 18th 04, 05:55 PM
G EddieA95
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Default Sedna, space probes?, colonies? what's next?

volatiles - from which biological material is constructed - not in a
deep gravity well, such as is found on the gas giants.

It is true that there are also Io and Europa, for example, but
radiation may be a problem with them, or other concerns, even
aesthetic ones, may be operable.


What is so nonaesthetic about the Jupiter system? It's not Saturn, but if (big
if) you could live on I&E without being cooked, Jupiter's proximity might be
the penultimate travel-photo op in Sol system
  #27  
Old March 18th 04, 05:58 PM
G EddieA95
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Default Sedna, space probes?, colonies? what's next?

Earth is certainly too crowded for solar power to
be sufficient here.


Hardly. 71% of it has no human life at all. We could *float* the solar
collectors. Places such as North Africa are good dry-land alternatives, though
there are political barriers there.

If Earth is not to become a pre-techological subsistence park, it will *have*
to be solar one day.
  #28  
Old March 18th 04, 07:00 PM
Dick Morris
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Default Sedna, space probes?, colonies? what's next?



Ian Stirling wrote:

John Savard wrote:
On Wed, 17 Mar 2004 16:50:48 +0100, "Uddo Graaf"
wrote, in part:

Colonies that far away from the Sun? Unlikely. Mankind can multiply like
rabbits and it would still take at least 300 years to fill up the inner
planets and moons.


Earth is already full, and not more than the tiniest fraction of its


Debatable.
Stick copies of biosphere II all over the world, and you end up with
well over 10 times the population.


How much did Biosphere II cost, per inhabitant?
  #29  
Old March 18th 04, 07:17 PM
Rand Simberg
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Default Sedna, space probes?, colonies? what's next?

On Thu, 18 Mar 2004 18:00:20 GMT, in a place far, far away, Dick
Morris made the phosphor on my monitor
glow in such a way as to indicate that:

Debatable.
Stick copies of biosphere II all over the world, and you end up with
well over 10 times the population.


How much did Biosphere II cost, per inhabitant?


A lot, but you can't conclude anything from that, since there were no
economies of scale.
  #30  
Old March 18th 04, 07:26 PM
Mike Combs
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Default Sedna, space probes?, colonies? what's next?

"Sander Vesik" wrote in message
...

I think there is a slight difference between 'can be done' and 'makes
sense to do' -


Oh, total agreement here. I was only trying to make the point that whatever
other objections might be raised, an inability to use solar power needn't be
one of them.

Personally, I can't see a reason for anybody to want to live at 10x the
distance of Pluto... unless they REALLY hate people.

given the distance, does it even make sense as a space
based source of ice/water?


There are surely lots of others between here and there.


--


Regards,
Mike Combs
----------------------------------------------------------------------
We should ask, critically and with appeal to the numbers, whether the
best site for a growing advancing industrial society is Earth, the
Moon, Mars, some other planet, or somewhere else entirely.
Surprisingly, the answer will be inescapable - the best site is
"somewhere else entirely."

Gerard O'Neill - "The High Frontier"


 




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