Fire in the sky, O'Neill colonies and asteroids

This is partly in answer to the Scientific American article about cosmic
rays likely preventing human spaceflight.

I have long believed that O'Neill colonies are vastly superior to Mars
or any other planetary surface as an abode for human life and development:

(a) They permit nearly total control over sunlight, day-night cycles,
temperature, atmosphere, radiation, and gravity, all of which can be
set at earth normal levels, or to almost any level you desire

(b) Initially they will be positioned in near earth-moon space reducing
the problems of radiation, transport, communication, and rescue.

(c) They have access to energy that is superior not only to that
which you find on Mars, but better than anything on earth -- solar
energy in free space far from the shadow, gravity, or atmosphere
of any large planet or moon has no rival

(d) When they are later built in the asteroid belt they have access
to materials enough for hundreds of times the surface area of
earth.

(e) Scaled down, highly modified versions of such colonies propelled
by Medusa type fission-fusion nuclear blasts will permit manned
interstellar flight

However, as Henry Spencer once told me, most believe that Mars colonies
can start out small whereas O'Neill colonies require huge up-front costs,
as the smallest Island I colony of O'Neill can't be made much smaller than
3 million tons if it is to provide earth normal gravity.

But two things have changed:

(a) Instead of the spheres or cylinders which cannot be made small
w/o sacrificing gravity, the Stanford Torus can be scaled down
dramatically while retaining full 1 gee

(b) Asteroids such as Nereus, which require only tiny amounts of
energy to move material to L5, drastically reduce the cost
of raw materials for L5

Here are the economic assumptions I make:

(a) All the costs are for production and transport, not design.

(b) The launch cost is assumed to be $1M/ton ($500/lb) to LEO, $4M/ton to
L5, and $5M/ton to soft landing on the Moon

(c) The cost of manufactured materials in space is set at $1M/ton (same
as current aerospace)

(d) The mass of material to be launched from the earth into space for
construction of a product is 20% larger than the mass of the final
product.


So first let us look at the O'Neill/Island One concept:

(a) The mass driver on the Moon weighs 10,000 tons and launches 600,000
tons/year at 2.4 km/sec for 6 years to send 3.6 M tons or 7.2B pounds
to L5. The cost would be:
$5M*(10,000 + 2000) + $1M*(10,000) = $70B or ~ $10/lb to L5

(b) The earth launch to L5 is 42,000 tons, so the cost is:
$4M*(42,000) + $1M*(42,000) = $210 Billion
So the total cost of Island One is $280 Billion

Now look at the Nereus/Torus based version:

(a) To move a 500,000 ton chunk of Nereus through a dV of 60 m/sec using
an ISP of 200 (about 2 km/sec) requires the expenditure of 15,000 tons
of material. If done over 5 years that equals 3000 tons/year. So the
size of this mass driver should be:
10000*(3000/600000)*(2/2.4)^2 = 35 tons.

To be conservative we will set it at 50 tons. It would take about
10 tons of Krypton at $10/oz using ion propulsion to send it to
Nereus, so the cost would be:
$1M*(50+10)+$1M*(50)+ $3.2M = $113M
but we will set it at $200M to be conservative. So 10 of these
would return 5M tons or 10B lbs to L5 at a cost of $2B or 20 cents/lb,
50 (!) times cheaper than launching it from the Moon.

(b) The full Stanford torus was 6000 feet in major diameter and 430 feet
in minor diameter, and weighed 250,000 tons (by the way, the Stanford
Torus site no longer appears to be available). The 250,000 tons refers
only to the raw structural mass w/o atmosphere, soil, water,
buildings, people and about 10,000,000 tons of cosmic ray shielding.

For the 1st colony I select 1500 feet in major diameter and 43 feet in
minor diameter, so using strict scaling it should be
(1/4)*(1/10)*(1/10) = 1/400 of the mass of the Stanford torus (the
last (1/10) occurs because the tube would be 1/10 as thick as well as
1/10 as wide). This yields a structural mass of 625 tons, but we will
set it at 1000 tons to be conservative.

We might need 200 tons of Krypton to move it to L5 ($32M worth). So
the cost would be:
$1M*(1000 + 200 + 200) + $1M*(1000) + $32M = 2.7 Billion, which
we will round to $3B

Now once the raw colony has been moved to L5 we will send 200 people
(at $1M/person for $200M) to L5 where they will not manufacture
anything but simply fill in the 250,000 tons for the cosmic ray
shield, soil, water and air (baked out of the asteroidal material),
and add seeds, plants, etc and settle down for a few years to learn
how to live there.

The next step is to build a 2nd identical colony. We will assume that
this will need only %10 of the material from earth, so the cost to
earth will be $300M. Once both colonies are in place and functioning
they will build the next one which has the same major diameter but a
minor diameter of 85 feet and can support 400 people, again for a cost
of $300M from earth.

So we end up with a cost of:
$2B for the 10 mass driver launches
$3M for the 1st small colony
$0.6B for two additional colonies
$0.8B to send 800 people to L5
------
$6.4 Billion

and we still end up with about 4M tons of material to play with,
enough for one Island One colony


There is a lot more I can say about this topic, and how it can be
expanded and moved to the asteroids, but I will stop for now.

-- Larry Gales

Lawrence Gales wrote:


(a) Instead of the spheres or cylinders which cannot be made small
w/o sacrificing gravity, the Stanford Torus can be scaled down
dramatically while retaining full 1 gee

What is this obsession with spheres, torii (toruses?) and cylinders? It's
very earth-bound thinking. As is the desire for one g, but let that slide.


Two modules with a long rope between them. Set them spinning, and you have
any gravity you like. In any size you like. Space is big, there is plenty of
room.


The longer the rope, the flatter the apparent gravity field - which is
something you can't do easily with a sphere, cylinder or torus, you have to
make those huge. Also it is less dizzy-making. And all it costs is a bit of
rope.




--
Peter Fairbrother

"Lawrence Gales" wrote in message
news:Pine.WNT.4.63.0603022344180.3940@your-kgj38sd53j...

interstellar flight

However, as Henry Spencer once told me, most believe that Mars colonies
can start out small whereas O'Neill colonies require huge up-front costs,
as the smallest Island I colony of O'Neill can't be made much smaller than
3 million tons if it is to provide earth normal gravity.

But two things have changed:

(a) Instead of the spheres or cylinders which cannot be made small
w/o sacrificing gravity, the Stanford Torus can be scaled down
dramatically while retaining full 1 gee

How?

ta

Ralph

Lawrence Gales wrote:

For the 1st colony I select 1500 feet in major diameter and 43
feet in
minor diameter, so using strict scaling it should be
(1/4)*(1/10)*(1/10) = 1/400 of the mass of the Stanford
torus (the last (1/10) occurs because the tube would be
1/10 as thick as well as 1/10 as wide). This yields a
structural mass of 625 tons, but we will set it at 1000
tons to be conservative.

Some comments:

1. You've gone from 1 rpm from the original Stanford design to 2 rpm
in your scaled down design to maintain 1 g. That will probably not be
acceptable.

2. 1000 tons is about 5 times the mass of ISS and yet you intend to
accomodate 200 people?

3. 1000 tons is about 4 times the mass of the Airbus A380 which cost
about $12 billion to develop and build and yet you estimate your
first torus cost at $3 billion?

Jim Davis

The size of the spacecraft payload determines how much sheilding we can
carry along - and this is determined by the size of the rocket, and the
power of that rocket.

When sheilding requirements are added in, chemical rockets become
impractical. However, nuclear pulse rockets are very practical - being
the right size, and right performance to carry along the needed
sheilding - both from cosmic sources, and the propulsion system! lol.

http://en.wikipedia.org/wiki/Nuclear_propulsion

Of course, a series of engineered nuclear explosions can also be used
to move asteroids, and can be used to move space colonies as well!

In fact, that would be a cool thing to do. Build a space colony, and
then attach a propulsor to move the colony, once established, to
another world, and then using that as an orbiting base, explore the
world with piloted and unpiloted vehicles descending and returning from
the surface.

You didn't say anything about the most basic question: Why do this at
all?

Why do it this was instead of another way?

Your numbers come out to $8,000,000 per person. Are they paying this
themselves, or are they welfare queens geting cushy govt handouts?

On Wed, 15 Mar 2006 19:41:29 -0000, in a place far, far away, Jim
Davis made the phosphor on my monitor glow
in such a way as to indicate that:

2. 1000 tons is about 5 times the mass of ISS and yet you intend to
accomodate 200 people?

It's not at all clear that number of people scales with mass, or that
ISS is a good model as to how to mass-efficiently build a space
habitat.

3. 1000 tons is about 4 times the mass of the Airbus A380 which cost
about $12 billion to develop and build and yet you estimate your
first torus cost at $3 billion?

It's not at all clear that an airliner is a good cost surrogate for a
space habitat.

In sci.space.tech, on Fri, 10 Mar 2006 08:39:49 +0000,
Peter Fairbrother sez:

` Lawrence Gales wrote:


` (a) Instead of the spheres or cylinders which cannot be made small
` w/o sacrificing gravity, the Stanford Torus can be scaled down
` dramatically while retaining full 1 gee

` What is this obsession with spheres, torii (toruses?) and cylinders? It's
` very earth-bound thinking. As is the desire for one g, but let that slide.


` Two modules with a long rope between them. Set them spinning, and you have
` any gravity you like. In any size you like. Space is big, there is plenty of
` room.


` The longer the rope, the flatter the apparent gravity field - which is
` something you can't do easily with a sphere, cylinder or torus, you have to
` make those huge. Also it is less dizzy-making. And all it costs is a bit of
` rope.

Not impossible, but there are two issues here. If the modules at each
end are active (as opposed to one being an inert counterweight), you
would want to be able to get from one to the other without performing
heroic measures (vacuum suit scrabbling). More importantly, docking
a ship and transferring supplies would be far too difficult without
a docking facility at the spin axis. These considerations drive the
design to a "dumbell", with a pressurized access tube and central
loading bay module rather than a simple rope. This of course has been
proposed before, the model being one of adding module pairs as needed
until you have built up a full circle.


--
================================================== ========================
Pete Vincent
Disclaimer: all I know I learned from reading Usenet.

On Wed, 15 Mar 2006, Jim Davis wrote:

Date: Wed, 15 Mar 2006 19:41:29 -0000
From: Jim Davis
Newsgroups: sci.space.policy, sci.space.tech
Subject: Fire in the sky, O'Neill colonies and asteroids

Lawrence Gales wrote:

For the 1st colony I select 1500 feet in major diameter and 43
feet in
minor diameter, so using strict scaling it should be
(1/4)*(1/10)*(1/10) = 1/400 of the mass of the Stanford
torus (the last (1/10) occurs because the tube would be
1/10 as thick as well as 1/10 as wide). This yields a
structural mass of 625 tons, but we will set it at 1000
tons to be conservative.

Some comments:

1. You've gone from 1 rpm from the original Stanford design to 2 rpm
in your scaled down design to maintain 1 g. That will probably not be
acceptable.
======================================
Well, O'Neill believed that it was acceptable, and it is my undestanding
that most be can be accustomed to 3 rpm, so 2 rpm should not be a stretch

=================================================


2. 1000 tons is about 5 times the mass of ISS and yet you intend to
accomodate 200 people?
=====================================
That is the raw structural weight w/o air, water, soil, shielding, etc. I
scaled it from the Stanford Torus which had 250 times the weight, but
based on other scalings that I saw on the Stanford Torus website (which
seems to have disappeared) it seems reasonable. Note that the 10,000
person torus offered huge open spaces and nearly luxury living, whereas
this initial colony is more of a construction shack. It does offer nearly
1000 feet^2 per person
=====================================



3. 1000 tons is about 4 times the mass of the Airbus A380 which cost
about $12 billion to develop and build and yet you estimate your
first torus cost at $3 billion?
======================================
I specifically stated that I did not include development costs -- only
production and transport costs.


-- Larry

================================================


Jim Davis

On Wed, 15 Mar 2006, William Mook wrote:

Date: Wed, 15 Mar 2006 19:41:46 -0000
From: William Mook
Newsgroups: sci.space.policy, sci.space.tech
Subject: Fire in the sky, O'Neill colonies and asteroids

The size of the spacecraft payload determines how much sheilding we can
carry along - and this is determined by the size of the rocket, and the
power of that rocket.

When sheilding requirements are added in, chemical rockets become
impractical. However, nuclear pulse rockets are very practical - being
the right size, and right performance to carry along the needed
sheilding - both from cosmic sources, and the propulsion system! lol.

http://en.wikipedia.org/wiki/Nuclear_propulsion

Of course, a series of engineered nuclear explosions can also be used
to move asteroids, and can be used to move space colonies as well!

In fact, that would be a cool thing to do. Build a space colony, and
then attach a propulsor to move the colony, once established, to
another world, and then using that as an orbiting base, explore the
world with piloted and unpiloted vehicles descending and returning from
the surface.

============================================
I completely agree: nuclear pulse rockets operating in deep space (and
hence free from the problems of nuclear fallout and EMP) are so vastly
superior to any other means of propulsion that I would be astounded that
NASA does not pursue them, except I know that NASA actually has zero
interest in real space flight.

-- Larry