Digest Number 416

From:
To:
Sent: Friday, March 29, 2002 9:18 PM
Subject: [spacesettlers] Digest Number 416

There are 6 messages in this issue.

Topics in this digest:

1. Re: The Space Elevator
From: Ravenart@...
2. Re: Re: [Webmind-TLC] Fw: The Space Elevator Comes Closer to
Reality
From: Ian Woollard
3. Space access: BDBs before beanstalks?
From: "John Frazer"
4. Re: Re: The Space Elevator
From: Ryan Healey
5. Re: Re: [Webmind-TLC] Fw: The Space Elevator Comes Closer to
Reality
From: rmenich@...
6. Re: Re: The Space Elevator
From: Ian Woollard

Message: 1
Date: Thu, 28 Mar 2002 10:51:16 EST
From: Ravenart@...
Subject: Re: The Space Elevator

Ok, here's my comment on space elevator.

First, I love the concept and I see that it can be done as there's no
natural
laws that forbid it. It will also lower the costs of transportation to
space
very dramatically after all the deprecations are done.

However, it dose have some disadvantages. One, is that due to the exotic
nature of the technology, it will have to be build in isolated areas (such
as
Kenya in Robert Heinlein's "Friday" as there will be a lot of people who
will
fear such technology with "NIMBY" lawsuits. Two, you still need to make
cheaper rocketships to help build this thing and to provide service in case
of trouble. Three, you will also need to create new robot crews that will
check and repair the cables up and down. Four, you will have to gain air
rights from the ground and from the neigbors up to geostationary location to
be on safe side (la "The Man Who Sold the Moon"). Fifth, speaking of safe
side, you still need large insurance regardless of which transportation you
build. Lastly, but most importantly from cashflow pov, is the time it take
the car to travel which can be a few hours at best, which also implys the
size of the car in order to be economical and profitable (in a word, BIG).
Even then, there would be some cagos that are too large or too dangerous
that
would requires specialized transportation. The best use for elevator to me
seems to be personal and luggage transporation.

It so happened that I was musing over such a concept recently, and my guts
tell me that a space elevator would be very very useful for the coach class
travelers such as college students and such who are not rich and need a
transportation system much like a bus and don't mind riding for hours. For
other people who needs to get somewhere in a hurry (such as business class
or
first class) or express packet delievery, rocketships will still be needed
as
the travel time can be in 20 min, given or taken. I don't see the elevator
and rocketships as competition because they can provide different services,
one for speed and one for low price, which mean they both can be very
profitable as the spacelines can charges higher prices and the elevator can
charge lower prices for different people. This is not either/or situation.
For space economy to thrive, we will need to create a network rich in
varsity
of transportation for different needs, kinda like a ecosystem. So, there's
room for elevators, rocketships, traveling space hotels, mass drivers and
other stuff. I would even invest in all of them once I have enough assets
for this kind of high risk business.

Carl Mullin
www.ravenartstudio.com

Message: 2
Date: Fri, 29 Mar 2002 00:24:55 +0000
From: Ian Woollard
Subject: Re: Re: [Webmind-TLC] Fw: The Space Elevator Comes Closer to
Reality

Lucio de Souza Coelho wrote:

> This new proposal for a space elevator is most interesting, for in the
> beginning you would just have to launch a geostationary satellite with 20
> tones of carbon nanotube thread (and 20 tones is perfectly achievable with
> current rocket technology). The tip of the thread is dropped back to Earth
> and then you extend a lot of new threads climbing the first one. In the
end
> you have a thick cable able to hold an space elevator weighting tens of
> tones going back and forth Earth surface and GEO.

Yeah. The only problem is the tether- nobody can actually build
a tether right now with the required strength.

A fiber with a tensile of 73 Gpa exists; the required strength
is 72.5 Gpa. However, a) we need a safety factor b) we need to
be able to splice the fibers together, and in practice that
loses 15-30% of the strength.

> That is FAR more feasible than all the space elevators proposals found in
> science fiction, were people put a carbonaceous asteroid in orbit and then
> start building the elevator with the asteroidal materials. Unfortunately,
> that is a chicken-and-egg problem: you cannot move an entire asteroid to
get
> easy access to space because we don't have easy access to space. This
clever
> solution of the cable 100% "made in Earth" may finally allow the chick to
> leave the egg.

Sure. He's solved all of the problems except one: WE NEED A
CABLE!

> Lucio Coelho
>
> From: "Anton Kolonin"
> To:
> Sent: Thursday, March 28, 2002 9:08 AM
> Subject: [Webmind-TLC] Fw: The Space Elevator Comes Closer to Reality
>
>>>ALBUQUERQUE, NEW MEXICO -- Make way for the ultimate high-rise project:
>>>the space elevator. Long viewed as science fiction "imagineering",
>>>researchers are gathering momentum in their pursuit to propel this
>>>uplifting concept into actuality.
>>>
>>>For the rest of this article, see
>>>http://www.space.com/businesstechnology/technology/space_elevator_020327
>>>-1.html
>>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>

- Ian Woollard (ian.woollard@...)

"Is a planetary surface the right place for an expanding
technological civilization?"
- Gerard O'Neill

Message: 3
Date: Thu, 28 Mar 2002 17:50:24 -0700
From: "John Frazer"
Subject: Space access: BDBs before beanstalks?

I'm as enthusiastic about space elevators as anyone. I tend to downplay the
almost miraculous capabilities of the Beanstalk in favor of more likely
things, like the hypersonic Skyhook and momentum-exchange & ED tethers.

Lucio de Souza Coelho wrote:
>in the beginning you would just have to launch a
>geostationary satellite with 20 tones of carbon
>nanotube thread (and 20 tones is perfectly
>achievable with current rocket technology). The
>tip of the thread is dropped back to Earth and
>then you extend a lot of new threads climbing the
>first one.
>FAR more feasible than all the space elevators
>proposals found in science fiction, where people
>put a carbonaceous asteroid in orbit and then
>start building the elevator with the asteroidal
>materials. Unfortunately, that is achicken-and-
>egg problem: you cannot move an entire asteroid
>to get easy access to space because we don't
>have easy access to space.

The problem isn't solved, because we can't yet make nanotube structures tens
of thousands of km long, let alone make them self-assembling.
Getting asteroidal resources doesn't require new magic ways of reaching
space.
Furthermore, asteroid resources aren't necessarily intended to give us
access to space. It's meant to give us something to do in space, with
immediate as well as long-term profitability. Parking an asteroid in HEEO
would give us far more than a mountain of carbon to build a beanstalk; It
gives us immediately valuable precious metals for sale, as well as more
mundane things like Al, Fe & concrete to make things out of. Things like
space factories (95%+ built out of simple asteroid materials) and GEO
antenna platforms immediately worth hundreds of billions annually (and over
90% made from simple materials)
Now if there were an asteroid handy, and hundreds of billions income being
made from it, we could probably make it worthwhile to launch things at
present ridiculously high artificially inflated prices -effectively giving
us convenient access to space.
Our problems with access to space aren't just the mechanics of getting
there, as they are dependant on political will.

Fairly straightforward development of Big Dumb Boosters from presently known
rockets would get access to asteroids far more readily than we could get
self-assembling planetary scale structures from materials which are
presently only laboratory curiosities.

A few examples of BDBs:
The Shuttle-C is fairly simple. No new rocket stages or launch facilities.
It could be simpler yet if you didn't use SSMEs for the upper stages and
didn't bother trying to re-use them.
http://www.astronautix.com/lvs/shuttlec.htm
http://www.astronautix.com/graphics/s/stsc89l.jpg
http://www.astronautix.com/graphics/s/stsc89o.jpg

Slightly higher performance with the Ares, but it requires a new ET to take
thrust directly, instead of via the normal orbiter attachments.
http://www.astronautix.com/lvs/ares.htm

It would probably be easier to develop something like the SEA Dragon than
self-assembling nanotube structures on the scale of a beanstalk.
http://www.astronautix.com/lvs/searagon.htm
http://www.astronautix.com/lvfam/truax.htm

As far as getting to space more conveniently & cheaply than at present, the
following has merits. (It doesn't even have to be re-usable or get back down
in one piece. We can build rockets down here; if we can get things started
up there, we don't need better than this. Back to the Sea Dragon?)
Space Ship Experimental
http://www.totse.com/en/technology/space_astronomy_nasa/ssx.html
The Case For SSX
Rockets have been our only way into space for over thirty years. They've
done the job, but recent events have made it all too clear that rockets as
we know them have problems. Current rockets are hideously expensive, costing
thousands of dollars per pound of payload. They're unreliable, with the loss
of one mission in twenty par for the course. They're inconvenient as hell,
with launches having to be booked years in advance.
These problems are not inherent to rockets. Most of our current space
vehicles were originally designed over thirty years ago as ballistic
missiles.
Their designs reflect both the limits of fifties technology and their
original military missions. Fifties missile design habits persist to this
day, despite changing missions and huge advances in the available
technology. Many of our current problems with rockets are a direct result of
approaching space vehicle design and operations as if nothing has changed in
the last thirty years.

Thirty years of progress in rocket engines and lightweight structures,
combined with a fresh approach to the problem, can give us space vehicles
far cheaper, safer, and more flexible than we're used to. One of our best
shots at doing this soon is a project called Space Ship Experimental -SSX.
http://www.spacefuture.com/archive/access_to_space_ssx.shtml
http://www.jerrypournelle.com/slowchange/SSX.html

>From: Anton Kolonin
>Subject: [Webmind-TLC] Fw: The Space
>Elevator Comes Closer to Reality
>>ALBUQUERQUE, NEW MEXICO -- Make way
>>for the ultimate high-rise project: the space
>>elevator. Long viewed as science fiction
>>"imagineering", researchers are gathering
>>momentum in their pursuit to propel this
>>uplifting concept into actuality.
http://www.space.com/businesstechnology/technology/space_elevator_020327-1.h
tml

Message: 4
Date: Thu, 28 Mar 2002 23:54:00 -0800 (PST)
From: Ryan Healey
Subject: Re: Re: The Space Elevator

--- Ravenart@... wrote:
> First, I love the concept and I see that it can be done as there's no
natural
> laws that forbid it. It will also lower the costs of transportation to
space
> very dramatically after all the deprecations are done.

To build one from the earth's surface we'd definately need nano-tech. You
really want to be careful with it. Other then that let's get to work
building
one.

> However, it dose have some disadvantages. One, is that due to the exotic
> nature of the technology, it will have to be build in isolated areas (such
as
> Kenya in Robert Heinlein's "Friday" as there will be a lot of people who
will
> fear such technology with "NIMBY" lawsuits.

On the equator (where it'd probably have to be) you shouldn't have a problem
with that.

> Two, you still need to make cheaper rocketships to help build this thing
and
> to provide service in case of trouble.

Cheaper rockets would help to build it. At first I'd prefer to start with a
simple Skyhook which we could oribt using only a few HLLV's and then work
up.
If we develop tethers along with rockets we'd be able to get better economy
out
of the rockets without comprimising safety. Service would probably be
pretty
hard to do by humans with a full earth to orbit elevator so you'd need it to
be
robotic. Probably using nano-robots.

> Three, you will also need to create new robot crews that will check and
> repair the cables up and down.

Nano-tech would probably have to be used in construction so the nano-bots
used
to build it could also be used to make sure it doesn't fall over.

> Four, you will have to gain air rights from the ground and from the
neigbors
> up to geostationary location to be on safe side (la "The Man Who Sold the
> Moon").

Earth orbit isn't considered to be owned by any country so you could just
build
something there without worry. It's only the airspace above what country
it's
building in that will matter for it. Might be a good idea to keep aircraft
away from it though.

> Fifth, speaking of safe side, you still need large insurance regardless of
> which transportation you build.

You might be able to get limited liability for it although if you design it
to
be as safe as possible and correct any defects you shouldn't have much of a
problem wtih law suits.

> Lastly, but most importantly from cashflow pov, is the time it take the
car
to
> travel which can be a few hours at best, which also implys the size of the
car
> in order to be economical and profitable (in a word, BIG).

A few hours is pretty quick up to GEO. Rockets would take you about half a
day
to get there. As for size of the car. You'll want it to have heavy walls
for
radiation reasons, namely It's going to be passing right through the Van
Allen
belts thus requring some shielding.

> Even then, there would be some cagos that are too large or too dangerous
that
> would requires specialized transportation. The best use for elevator to
me
> seems to be personal and luggage transporation.

When it comes to safety if it's going to blow up on a space elevator it'll
probably blow up if it's launched on a rocket. A space elevator would be
better for dangerous cargos because the car can be quite heavy so it could
be
made [bomb|germ|bullet|acid|whatever]proof a lot easier then a light flimsy
rocket.

For large cargos the car of the space elevator could be made much larger
then
any rocket we'd be able to build cheaply. People and Luggage transporation
would also be better done on a space elevator for safety and economics
reasons.

> It so happened that I was musing over such a concept recently, and my guts
> tell me that a space elevator would be very very useful for the coach
class
> travelers such as college students and such who are not rich and need a
> transportation system much like a bus and don't mind riding for hours.

To GEO which is where you'd get off taking the space elevator you'll spend
less
time taking the elevator then taking a rocket. There will probably still be
different classes of passage although like on current aircraft first class
passengers will just get a bigger seat and better service then economy class
(along with being in a slightly quiter part of the aircraft).

> For other people who needs to get somewhere in a hurry (such as business
class
> or first class) or express packet delievery, rocketships will still be
needed

> as the travel time can be in 20 min, given or taken.

20 minutes is only to LEO. If you want to get to GEO it'll take almost half
a
day to go there from LEO. You could get there faster expending more fuel
but a
space elevator could probably beat the rocket to GEO.

> I don't see the elevator and rocketships as competition because they can
> provide different services, one for speed and one for low price, which
mean
> they both can be very profitable as the spacelines can charges higher
prices
> and the elevator can charge lower prices for different people. This is
not
> either/or situation.

When space elevators are built I'd expect quite a large drop off in rocket
travel from the earth as the elevator is a lot cheaper, probably safer and
probably quicker. Rockets will still be used to travel between the planets
but
with the assitance of tethers (and that elevator, go right to the top a long
way beyond GEO and let go).

> For space economy to thrive, we will need to create a network rich in
varsity
> of transportation for different needs, kinda like a ecosystem. So,
there's
> room for elevators, rocketships, traveling space hotels, mass drivers and
> other stuff. I would even invest in all of them once I have enough assets
> for this kind of high risk business.

We can get different types of transportation methods although we do need to
realise that often one method will be the best one for a specific type. If
we
can we should use that although it may be it'd be too expensive so the
second
best could be used.

Message: 5
Date: Fri, 29 Mar 2002 08:36:59 -0500
From: rmenich@...
Subject: Re: Re: [Webmind-TLC] Fw: The Space Elevator Comes Closer to
Reality

Ian Woollard wrote,

"A fiber with a tensile of 73 Gpa exists; the required strength
is 72.5 Gpa. However, a) we need a safety factor b) we need to
be able to splice the fibers together, and in practice that
loses 15-30% of the strength."

What is the required strength for a space elevator from the Lunar surface
to lunar orbit?
Do currently-existing materials suffice to build such a lunar elevator?
Would a lunar elevator be a simpler technological solution to the problem
of moving large amounts of material off the moon than the O'Neill-heritage
mass driver/mass catcher system?

Ron Menich
********************

Ian Woollard
03/28/02 07:24 PM
Please respond to spacesettlers

To: spacesettlers@yahoogroups.com
cc: webmind@yahoogroups.com
Subject: Re: [spacesettlers] Re: [Webmind-TLC] Fw: The Space
Elevator Comes Closer
to Reality

Lucio de Souza Coelho wrote:

> This new proposal for a space elevator is most interesting, for in the
> beginning you would just have to launch a geostationary satellite with
20
> tones of carbon nanotube thread (and 20 tones is perfectly achievable
with
> current rocket technology). The tip of the thread is dropped back to
Earth
> and then you extend a lot of new threads climbing the first one. In the
end
> you have a thick cable able to hold an space elevator weighting tens of
> tones going back and forth Earth surface and GEO.

Yeah. The only problem is the tether- nobody can actually build
a tether right now with the required strength.

A fiber with a tensile of 73 Gpa exists; the required strength
is 72.5 Gpa. However, a) we need a safety factor b) we need to
be able to splice the fibers together, and in practice that
loses 15-30% of the strength.

> That is FAR more feasible than all the space elevators proposals found
in
> science fiction, were people put a carbonaceous asteroid in orbit and
then
> start building the elevator with the asteroidal materials.
Unfortunately,
> that is a chicken-and-egg problem: you cannot move an entire asteroid to
get
> easy access to space because we don't have easy access to space. This
clever
> solution of the cable 100% "made in Earth" may finally allow the chick
to
> leave the egg.

Sure. He's solved all of the problems except one: WE NEED A
CABLE!

> Lucio Coelho
>
> From: "Anton Kolonin"
> To:
> Sent: Thursday, March 28, 2002 9:08 AM
> Subject: [Webmind-TLC] Fw: The Space Elevator Comes Closer to Reality
>
>>>ALBUQUERQUE, NEW MEXICO -- Make way for the ultimate high-rise project:
>>>the space elevator. Long viewed as science fiction "imagineering",
>>>researchers are gathering momentum in their pursuit to propel this
>>>uplifting concept into actuality.
>>>
>>>For the rest of this article, see
>>>http://www.space.com/businesstechnology/technology/space_elevator_020327
>>>-1.html
- Ian Woollard (ian.woollard@...)

"Is a planetary surface the right place for an expanding
technological civilization?"
- Gerard O'Neill

Message: 6
Date: Fri, 29 Mar 2002 17:02:05 +0000
From: Ian Woollard
Subject: Re: Re: The Space Elevator

Ryan Healey wrote:

> --- Ravenart@... wrote:
>
>>First, I love the concept and I see that it can be done as there's no
natural
>>laws that forbid it. It will also lower the costs of transportation to
space
>>very dramatically after all the deprecations are done.
>>
>
> To build one from the earth's surface we'd definately need nano-tech. You
> really want to be careful with it. Other then that let's get to work
building
> one.

Nobody knows quite how to do it. But it looks at the moment
like nanotech is not required- the materials are pretty near
term already. (Nanotubes aren't exactly nanotech in any
classical sense.)

>>However, it dose have some disadvantages. One, is that due to the exotic
>>nature of the technology, it will have to be build in isolated areas (such
as
>>Kenya in Robert Heinlein's "Friday" as there will be a lot of people who
will
>>fear such technology with "NIMBY" lawsuits.
>>
>
> On the equator (where it'd probably have to be) you shouldn't have a
problem
> with that.

Yes. In the ocean. They fall down occasionally.

>>Two, you still need to make cheaper rocketships to help build this thing
and
>>to provide service in case of trouble.
>>
>
> Cheaper rockets would help to build it. At first I'd prefer to start with
a
> simple Skyhook which we could oribt using only a few HLLV's and then work
up.
> If we develop tethers along with rockets we'd be able to get better
economy out
> of the rockets without comprimising safety. Service would probably be
pretty
> hard to do by humans with a full earth to orbit elevator so you'd need it
to be
> robotic. Probably using nano-robots.

If the target strength is achieved, then the initial elevator
would be about 20 tonnes. This is easily within the
capabilities of several launchers including the Space Shuttle.

Once you have one thin cable, you send more cables up the
first, and then more launchers aren't required.

>>Three, you will also need to create new robot crews that will check and
>>repair the cables up and down.
>>
>
> Nano-tech would probably have to be used in construction so the nano-bots
used
> to build it could also be used to make sure it doesn't fall over.

Used properly, it can't fall over. It will probably be made
using multiple connected strands, several failures would be
survivable unless they all happen at the same point, but that's
unlikely. Repair should be possible. No nanotech; although
nanotech would make it easier. Still, nanotech seems further
away than the space elevator right now.

>>Four, you will have to gain air rights from the ground and from the
neigbors
>>up to geostationary location to be on safe side (la "The Man Who Sold the
>>Moon").
>>
>
> Earth orbit isn't considered to be owned by any country so you could just
build
> something there without worry. It's only the airspace above what country
it's
> building in that will matter for it. Might be a good idea to keep
aircraft
> away from it though.

Yeah. Probably going to be built in international waters in
fact; for safety reasons. Ironic really, it's a bridge to
space, but one end is in the middle of water.

>> Lastly, but most importantly from cashflow pov, is the time it take the
car
>> to travel which can be a few hours at best, which also implys the size of
the
>> car
>
>>in order to be economical and profitable (in a word, BIG).
>>
>
> A few hours is pretty quick up to GEO. Rockets would take you about half
a day
> to get there. As for size of the car. You'll want it to have heavy walls
for
> radiation reasons, namely It's going to be passing right through the Van
Allen
> belts thus requring some shielding.
>

The mass of the cars is limited by the size of the elevator
cable. If you try to lift too much at any one time, it snaps.
But you can use the elevator to grow the elevator (use the
elevator to lift more cables up).

The cars will have some shielding, but this will continue to be
an issue to some extent. The cars may not have enough mass to
obviate this problem.

- Ian Woollard (ian.woollard@...)

"Is a planetary surface the right place for an expanding
technological civilization?"
- Gerard O'Neill