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A Moon base is too far; an asteroid ship better alternative:)



 
 
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  #11  
Old February 5th 05, 01:09 PM
Big Show
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Really, it is hard to decide if it should be moon, mars or asteroids
first. Those 3 are the stepping stones without much doubt but in which
order do they come for us? I wish somebody could weigh up the pros and
cons and map out a 100 year plan with computation. I think the dude's
phrase: "The destiny of our species rests on the simple toss of a
coin..." is rather apt. Well done Mr. Ahad for a thought provoking
article!

  #12  
Old February 6th 05, 11:57 PM
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Kent Paul Dolan wrote:
"Malcolm Street" wrote:

All you need to do is get a dinosaur-killer-sized
asteroid into orbit closer than the moon without
risking it hitting the earth.


No, and no. You don't have to start with something
10 km in diameter, 200 m in diameter is a huge good
start for just getting a lot of mass available that
isn't at the bottom of (quite so deep) a gravitational
well, and you don't have to get it physically closer
than the material on the moons surface, just
energetically closer, which any stable Lagrangian
point orbit would suffice to accomplish.

Right, but 200m is still way too big - that's about 8 million tons. For
a first attempt, go for about 20m diameter - about 8,000 tons.

Now that Smart-1 has proved humankind capable of doing
space the slow and steady way, what _are_ the
implications for robotically shipping a "rock" from
the asteroid belt to L5, probably (I have no clue how
to do the math) simpler than diverting something in a
profoundly non-circular solar orbit, like an earth's
orbit transiting asteroid, if one is willing to be
patient.

Forget asteroid belt rocks, there are NEOs which can be captured with
just 169m/s Delta V. Lets assume a Delta V requirement might be 300m/s.
Exhaust velocity might be 30,000 m/s, so you'd need to "burn" 1% of the
asteroid, or 80 tons in a plasma engine. That's why I keep asking
about Oxygen fuelled plasma engines, since oxygen is a fuel that can be
got from most asteroids, or the moon.


And, what constitutes a big enough "rock" to be worth
the effort?

NEOs - 8,000 tons is plenty for starters - it would:

1. Provide shielding for a base for dozens of people.
2. Allow, assuming suitable techniques, the manufacture of a 100 MW
solar array
3. Allow, assuming suitable techniques, a mission to be assembled to
fetch a NEO with a mass of 200,000 tons.

  #13  
Old February 16th 05, 07:38 PM
Mike Combs
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"Fred J. McCall" wrote in message
...

Except most of our industrial processes work better in the presence of
at least some gravity. It makes a lot of things a lot more
convenient.


For any industrial process where some gravity is advantageous, don't forget
that a suitable substitute can be arranged for in an orbital facility by
having a portion of it rotate. On the other hand, if there are any
industrial processes where 0-G was where the advantage lay, one could have
that too; but couldn't have it on the lunar surface.

But the latter is not the primary argument for processing in HEO over the
lunar surface. The primary arguments are the gravity well issues, and the
continuous availability of sunlight in a sufficiently-high orbit. For as
long as a portion of an orbital facility can be made to rotate, there's
simply no reason to abandon these significant advantages just because we
need some material to settle or separate.

I'd think you just chuck it into a crater from on high and then go
strip mine it out. No 'landing it' necessary. Little to no
atmosphere means you can use solar furnaces for smelting.


For 2 weeks out of every 4. In HEO, those solar furnaces can run 24/7. And
can be made arbitrarily large.


--


Regards,
Mike Combs
----------------------------------------------------------------------
Member of the National Non-sequitur Society. We may not make
much sense, but we do like pizza.


  #14  
Old February 26th 05, 07:33 PM
Rodney Kelp
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If the moon is a piece of the earth then there should be enough raw
materials to build the moon base from moon materials. All you need do is
bring the technology there to build with. You don't need to shuttle
everything from the earth or an asteroid.


"Bounty" wrote in message
oups.com...
Okay shoot me down if you have to but I think that "Ahad" guy had a
neat idea and was on the right track with his "Celestial Titanic" ship:

http://uk.geocities.com/aa_spaceagen...arth-ring.html

Just look at all these squillions of $$$ benefits:

-Save billions of dollars in ferrying up parts from Earth to build the
large-scale outer framework

-Save thousands of man hours and hundreds of radiation-exposed
astronaut spacewalks for station assembly

-Asteroid surface offers strong commercial potential for mining
precious minerals

-Bulk of the project from in-situ excavation, transportation of
asteroid to high Earth orbit and some initial mining, performed
robotically. Human crews arrive near the end to "seal the entrance" and
establish colony

-Opportunity to experiment re-creating a "miniature Earth" with
gravity, biosphere and self-sustaining ecosystem within a natural,
rocky structure much like Earth's own crust

-Logistically more attractive for easier access from the ground than
either a base on the Moon or one established on Mars

-First "truly promising", permanent off-Earth colony potential within
decades!

-Potentially a full-function transportation vessel for sailing the
great interplanetary or even interstellar oceans of space...

Why oh why do I want to go all the way to that grey thing, when there's
more economical business to be done nearer home with the right rock
from outer space? This is a smart idea - was a smart idea... still
plain wishful thinking.

Bounty



  #15  
Old February 26th 05, 07:36 PM
Rodney Kelp
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"Malcolm Street" wrote in message
...
Bounty wrote:

Why oh why do I want to go all the way to that grey thing, when there's
more economical business to be done nearer home with the right rock
from outer space? This is a smart idea - was a smart idea... still
plain wishful thinking.

All you need to do is get a dinosaur-killer-sized asteroid into orbit
closer
than the moon without risking it hitting the earth. Funnily enough, I
think a lot of people mightn't like that idea.

Good luck being allowed to do it even without technical obstacles.


There are plenty of asteroids burried in the lunar crust.

I think asteroids in the longer term have a major role to play in space
exploration and colonisation, but FFS keep 'em away from the earth! :-)

--
Malcolm Street
Canberra, Australia
The nation's capital



  #16  
Old March 13th 05, 02:40 PM
Fred J. McCall
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"Mike Combs" wrote:

:"Fred J. McCall" wrote in message
.. .
:
: Except most of our industrial processes work better in the presence of
: at least some gravity. It makes a lot of things a lot more
: convenient.
:
:For any industrial process where some gravity is advantageous, don't forget
:that a suitable substitute can be arranged for in an orbital facility by
:having a portion of it rotate. On the other hand, if there are any
:industrial processes where 0-G was where the advantage lay, one could have
:that too; but couldn't have it on the lunar surface.
:
:But the latter is not the primary argument for processing in HEO over the
:lunar surface. The primary arguments are the gravity well issues, and the
:continuous availability of sunlight in a sufficiently-high orbit. For as
:long as a portion of an orbital facility can be made to rotate, there's
:simply no reason to abandon these significant advantages just because we
:need some material to settle or separate.

Except if you do the processing in HEO you have to lift all the RAW
material (much higher mass) from somewhere. If you do the processing
on the lunar surface (using local raw materials) you're only lifting
the refined stuff out (at least an order of magnitude less mass to
lift).

: I'd think you just chuck it into a crater from on high and then go
: strip mine it out. No 'landing it' necessary. Little to no
: atmosphere means you can use solar furnaces for smelting.
:
:For 2 weeks out of every 4.

Dig for 2, smelt for 2.

:In HEO, those solar furnaces can run 24/7. And
:can be made arbitrarily large.

And now every bit of stuff you have to move to/from a furnace is an
orbital change. No gravity at your furnace, so lots of 'normal'
separation processes won't work well.

If you dump it on the Moon, no fancy precision orbits are required.

--
"Some people get lost in thought because it's such unfamiliar
territory."
--G. Behn
  #17  
Old March 14th 05, 06:40 PM
Joe Strout
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In article ,
"Fred J. McCall" wrote:

Except if you do the processing in HEO you have to lift all the RAW
material (much higher mass) from somewhere. If you do the processing
on the lunar surface (using local raw materials) you're only lifting
the refined stuff out (at least an order of magnitude less mass to
lift).


Only if you're not making use of the entire buffalo -- er, lifted mass I
mean. Most plans assume that you do use it all; the leftover slag from
the refinement processes become your habitat shielding, which you need
anyway.

:In HEO, those solar furnaces can run 24/7. And
:can be made arbitrarily large.

And now every bit of stuff you have to move to/from a furnace is an
orbital change. No gravity at your furnace, so lots of 'normal'
separation processes won't work well.


Not a significant orbital change if it's all in the same complex
(essentially the same orbit).

And where you want a gravity-style separation process, you simply use a
centrifuge (or the equivalent, a continuously rotating processing
module). Maybe 1/6 G isn't the amount of acceleration you need anyway.
And note that the "normal" separation processes inherent in doing
metallurgy on a planet also prevent you from making lots of potentially
useful alloys. The flexibility of orbital processing is going to be
hard to beat, once we get over the hump in R&D.

Best,
- Joe

,------------------------------------------------------------------.
| Joseph J. Strout Check out the Mac Web Directory: |
| http://www.macwebdir.com |
`------------------------------------------------------------------'
  #18  
Old March 15th 05, 02:41 PM
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wrote:
Kent Paul Dolan wrote:
"Malcolm Street" wrote:

All you need to do is get a dinosaur-killer-sized
asteroid into orbit closer than the moon without
risking it hitting the earth.


No, and no. You don't have to start with something
10 km in diameter, 200 m in diameter is a huge good
start for just getting a lot of mass available that
isn't at the bottom of (quite so deep) a gravitational
well, and you don't have to get it physically closer
than the material on the moons surface, just
energetically closer, which any stable Lagrangian
point orbit would suffice to accomplish.

Right, but 200m is still way too big - that's about 8 million tons.

For
a first attempt, go for about 20m diameter - about 8,000 tons.

Now that Smart-1 has proved humankind capable of doing
space the slow and steady way, what _are_ the
implications for robotically shipping a "rock" from
the asteroid belt to L5, probably (I have no clue how
to do the math) simpler than diverting something in a
profoundly non-circular solar orbit, like an earth's
orbit transiting asteroid, if one is willing to be
patient.

Forget asteroid belt rocks, there are NEOs which can be captured with
just 169m/s Delta V. Lets assume a Delta V requirement might be

300m/s.
Exhaust velocity might be 30,000 m/s, so you'd need to "burn" 1% of

the
asteroid, or 80 tons in a plasma engine. That's why I keep asking
about Oxygen fuelled plasma engines, since oxygen is a fuel that can

be
got from most asteroids, or the moon.


I believe the lighter the molecule in the exhaust, the more efficient
the engine? If so, it might be better to make pellets of silicon (MW=
14) as we process the asteroid, charge them, and accelerate them using
an electrostatic engine. Oxygen has a molecular weight of 16, would be
rather corrosive in a high-temp exhaust, and is more useful than
silicon for other purposes.

  #19  
Old March 15th 05, 08:12 PM
Mike Combs
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"Fred J. McCall" wrote in message
...

Except if you do the processing in HEO you have to lift all the RAW
material (much higher mass) from somewhere.


Joe has already made the point that the leftover slag is useful as radiation
shielding. If the slag weren't available for use as shielding, we'd have to
lift the equivalent mass of some other material anyway.

If you do the processing
on the lunar surface (using local raw materials) you're only lifting
the refined stuff out (at least an order of magnitude less mass to
lift).


Are you sure about that "order of magnitude" assertion? The oxygen is
valuable for breathing, making water, and as rocket oxidzer. The silicon is
useful for solar cells and glass-making. The metals are obviously useful.
When it comes to raw materials, space industries may use every part of the
pig but the squeal, as the saying goes.

Dig for 2, smelt for 2.


There are advantages to continuous operation. What you can never get around
is that twice as much solar energy is available outside the shadows of
planets and moons.

And now every bit of stuff you have to move to/from a furnace is an
orbital change.


So? We tend to think orbital changes are a big deal because, after all,
it's "space travel". But minor orbital changes are a much easier kind of
space travel than the kind we're typically thinking about: namely getting
from where we presently sit into orbit.

No gravity at your furnace, so lots of 'normal'
separation processes won't work well.


No gravity at the focus of the space mirror, but there's no reason why there
couldn't be centrifugal forces at any other point in the material flow where
it's advantageous.

If you dump it on the Moon, no fancy precision orbits are required.


I'd consider being isolated from your power supply 50% of the time (for two
weeks at a time) to be a greater problem in need of a solution than the
modest requirements for orbital station-keeping.

--


Regards,
Mike Combs
----------------------------------------------------------------------
Member of the National Non-sequitur Society. We may not make
much sense, but we do like pizza.


  #20  
Old March 15th 05, 11:01 PM
Gene P.
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On Tue, 15 Mar 2005, Mike Combs wrote:

[snip]
I'd consider being isolated from your power supply 50% of the time (for two
weeks at a time) to be a greater problem in need of a solution than the
modest requirements for orbital station-keeping.

[snip]

I've got 2 different answers to this non-issue:

1. The Lunar Power Grid + electric furnace. Who cares if the electricity
comes from solar panels on the other side of the moon or from a great big
nuclear pile a couple of miles away...

2. Space furnace mirrors can point down at the lunar surface just as
easy as at an orbital processing facility...




--
Alcore Nilth - The Mad Alchemist of Gevbeck



 




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