Cost of launch and laws of physics

(gbaikie) wrote in message om...

I think a Space elevator would need a high volume of traffic to
economically have a chance of working. A higher volume of traffic
would also "solve" the problem with the high cost of rockets- and I
think you need significantly less volume is needed with rockets.

No reason why you can't have _both_, of course. Rockets to deliver
people or low mass goods, space elevator to deliver large bulky items.

To there is the question of demand; there wont' be demand for cheap
access to space until there is a viable solution in place. There
won't be a viable solution built until there is demand ....

And
even a space elevator made of long nano carbon would need lots of mass
in space which could done at lower cost if you already had significant
infrastructure in space. Plus their would be significantly more
political will for doing this elevator.

Perhaps you're underestimating the amount of lift needed for the first
SE? Liftport's scheme involves 4-5 flights Delta flights. Total.

Finally, the market for this new stronger material which makes a space
elevator "seem possible" would have much higher demand currently for
things like bridges. You could sell this stuff tomorrow to some bridge
project, whereas you would need to wait for the elevator to begin
construction- and if NASA or some govt was doing it could take a
decade or more before plans were finalized.

No reason the same factory which is producing ribbon for the SE
couldn't make/sell CNT cables for other purposes at the same time.

And finally I wonder about the gravity losses- the slower to orbit the
more significant this becomes- the faster you accelerate and the
higher speeds you attain on a Space elevator the more problematic it
becomes. I think that if you could wave a magic wand and have a space
elevator magically appear, that rockets could still out compete it-
assuming now no laws were passed preventing this competition.

I'm not so sure about that. There is room in the world for both FedEx
AND Burlington-Northern, yes? Each ship goods the other can't or
won't. It seems to me the same will be true of rockets vs. elevators.

To there is the question of demand; there wont' be demand for cheap
access to space until there is a viable solution in place. There
won't be a viable solution built until there is demand ....

The viable solution is that the US govt "does things" which would
encourage opening the space frontier. Doing things which do not
effectively open the space frontier are things like operating the
Space Shuttle job program and having such poor laws that it takes 6
months to get permission to launch into space. The govt needs to focus
on doing things which could open new markets in Space- exploring the
Moon to determine if there is minable deposits of water is one
example.

And
even a space elevator made of long nano carbon would need lots of mass
in space which could done at lower cost if you already had significant
infrastructure in space. Plus their would be significantly more
political will for doing this elevator.

Perhaps you're underestimating the amount of lift needed for the first
SE? Liftport's scheme involves 4-5 flights Delta flights. Total.

You can make money by delivering more product or you can charge more
per product, any space elevator (including even one you didn't pay to
develop and construct) would need to make lots of money per year. And
a govermental cost anlysis should include all costs.

Finally, the market for this new stronger material which makes a space
elevator "seem possible" would have much higher demand currently for
things like bridges. You could sell this stuff tomorrow to some bridge
project, whereas you would need to wait for the elevator to begin
construction- and if NASA or some govt was doing it could take a
decade or more before plans were finalized.

No reason the same factory which is producing ribbon for the SE
couldn't make/sell CNT cables for other purposes at the same time.

Yes, but if you are focusing on a market which needs the product 10
years after you make it, you are focusing on wrong market. Now,
probably what the thinking is that NASA will pay a higher price per
unit of product, this is wrong approach and will fail.

And finally I wonder about the gravity losses- the slower to orbit the
more significant this becomes- the faster you accelerate and the
higher speeds you attain on a Space elevator the more problematic it
becomes. I think that if you could wave a magic wand and have a space
elevator magically appear, that rockets could still out compete it-
assuming now no laws were passed preventing this competition.

I'm not so sure about that. There is room in the world for both FedEx
AND Burlington-Northern, yes? Each ship goods the other can't or
won't. It seems to me the same will be true of rockets vs. elevators.

As I said elevators have a higher cost of infrastructure as compared
to rockets, though, if there is lots of demand, both could stay in
business.
But remember the supposed purpose of spending billions of dollars to
make a space elevator is to get a lower cost to orbit- and we already
have a way to get there at a lower cost: chemical rockets. The key is
NOT technology, the key is increasing the market demand for launches.

gbaikie wrote:
To there is the question of demand; there wont' be demand for cheap
access to space until there is a viable solution in place. There
won't be a viable solution built until there is demand ....
snip
No reason the same factory which is producing ribbon for the SE
couldn't make/sell CNT cables for other purposes at the same time.

Yes, but if you are focusing on a market which needs the product 10
years after you make it, you are focusing on wrong market. Now,
probably what the thinking is that NASA will pay a higher price per
unit of product, this is wrong approach and will fail.

CNT cables have applications practically everywhere, from Architecture to
Zymurgy.
snip
As I said elevators have a higher cost of infrastructure as compared
to rockets, though, if there is lots of demand, both could stay in
business.
But remember the supposed purpose of spending billions of dollars to
make a space elevator is to get a lower cost to orbit- and we already
have a way to get there at a lower cost: chemical rockets. The key is
NOT technology, the key is increasing the market demand for launches.

It depends on the numbers.
Chemical rockets can certainly get to $1000/Kg.
Certainly not to $1/Kg.

However, tethers might well hit that last limit, with a mature system,
and plenty of throughput.


--
http://inquisitor.i.am/ | | Ian Stirling.
---------------------------+-------------------------+--------------------------
Among a mans many good possessions, A good command of speech has no equal.

(gbaikie) wrote in message . com...
To there is the question of demand; there wont' be demand for cheap
access to space until there is a viable solution in place. There
won't be a viable solution built until there is demand ....

The viable solution is that the US govt "does things" which would
encourage opening the space frontier. Doing things which do not
effectively open the space frontier are things like operating the
Space Shuttle job program and having such poor laws that it takes 6
months to get permission to launch into space. The govt needs to focus
on doing things which could open new markets in Space- exploring the
Moon to determine if there is minable deposits of water is one
example.

Good luck getting the government to do `anything` with a payoff whose
date is further off than the next election.

Finally, the market for this new stronger material which makes a space
elevator "seem possible" would have much higher demand currently for
things like bridges. You could sell this stuff tomorrow to some bridge
project, whereas you would need to wait for the elevator to begin
construction- and if NASA or some govt was doing it could take a
decade or more before plans were finalized.

No reason the same factory which is producing ribbon for the SE
couldn't make/sell CNT cables for other purposes at the same time.

Yes, but if you are focusing on a market which needs the product 10
years after you make it, you are focusing on wrong market. Now,
probably what the thinking is that NASA will pay a higher price per
unit of product, this is wrong approach and will fail.

So? I'm John the CNT ribbon maker. I don't care what my customers
_do_ with my product, aside from liability issues. You want to make
ribbon for a new suspension bridge? Ribbon for a space elevator?
Give the specs Bub, and cash on the barrel head.

Market focus? There is exactly one company contemplating building an
SE. Small market .. for a SE ribbon. Large market for `everything
else you could use a ribbon for`. I don't see how the CNT ribbon
maker looses by focusing on one customer. They'll be paying for the
product.

I'm not so sure about that. There is room in the world for both FedEx
AND Burlington-Northern, yes? Each ship goods the other can't or
won't. It seems to me the same will be true of rockets vs. elevators.

As I said elevators have a higher cost of infrastructure as compared
to rockets, though, if there is lots of demand, both could stay in
business.

I'm not sure about the higher cost of infrastructure.

But remember the supposed purpose of spending billions of dollars to
make a space elevator is to get a lower cost to orbit- and we already
have a way to get there at a lower cost: chemical rockets. The key is
NOT technology, the key is increasing the market demand for launches.

I agree with your last statement. But. NASA, the guv'mint, and the
big corporations have a lock on space - and for various and sundry
reasons they aren't going to give it up. Think of the SE as a means
to side step The Man and deliver CATS without their quite realizing
what's going on ....

I agree with your last statement. But. NASA, the guv'mint, and the
big corporations have a lock on space - and for various and sundry
reasons they aren't going to give it up. Think of the SE as a means
to side step The Man and deliver CATS without their quite realizing
what's going on ....

and again, this plan only works if you have materials that don't
exist, and a market for going to space via elevator that doesn't
exist.

Ian Stirling wrote in message ...
gbaikie wrote:

ground. It seems like they simply didn't want to think, but simply
plugged in some numbers. Hanging a cable from the "ground" to first 5
miles from surface would be problematic, but you could build a

The problem isn't the first 5, or even 500 miles, it's the rest.

"I would think the problem is the first 500 miles up, because above
this the orbital speed of the cable would reduce it's weight and you

You may think so, unfortunately, the equations don't care what you think.

At 500 miles, gravity (for something in a 24 hour 'orbit') is still
around 90% of what it is at the ground.

Yes, around 90%, but you also need to add the increased speed from the
spin of Earth at 500 miles up. Earth diameter is 12,756.3 add 800 km.
Earth's circumference is 40,075 km & at 800km with circumference of
42,588 km. Now this affect is small at 500 miles, but you are getting
a gradual improvement the higher you go up. Carbon and aluminum have a
better weight to strength ratio than steel, but as you get higher the
weight of your material is effectively getting less- thereby increases
it's weight to strength ratio. The choice of material is "all about"
it's tension strength in comparison to it's weight. Steel is about 7.8
times heavier than water, reduce steel's weight by 90% and you get 7
instead of 7.8. Now of course steel doesn't lose it's mass, but mass
isn't the issue, in fact the more mass, the better as it adds
stability. Plus with more mass you have other small affects, which can
make the material lighter, and if we are in the range of million of
tons then gravity of the material itself can have a small effect. And
if we are using steel than there is also a possible option of using
magnetic force (say having part of structure be large permanant
magnet) again, the magnet does need to be a big factor, just one more
piece to lower the weight at the lower end.
GEO is "42,164 km from the center of the Earth, i.e. 35,787 km above
sea level." http://www.wikipedia.org/wiki/Geostationary_orbit
21,000 km is halfway to GEO from center of earth and is about 15,000
km (9,000 miles) from Earth surface. Now, let's focus this halfway
point out to GEO & beyond. Let's say for simplicity beyond the halfway
point the steel is less that 50% it's weight and at 3/4 point it's
25%, At GEO it's zero, and at 1 1/4 it's back to 25% (pulling away
from Earth).
Ok, first I'm "just" going to assign a market value for "stuff" in
Space. The price per ton of steel will be $1000 per ton and the price
of rock will be 10 cents per ton. At these prices I would be buying a
lot of rock, and at this price a asteriod 1 km in diameter could be
worth hundreds of millions of dollars. Now, it's quite possible I
could get these rocks for free- I could offer a place to dock these
rocks while they are processed- humans could live near the work area
and stuff could be shipped down to Earth cheaply, and once at Earth
surface transported via ships. Also with one asteriod such as "dog
bone asteriod" which would have trillions of dollars in metals, I
could also get lower price on steel since I'm buying in such quantity.
But anyway I need simply lots of mass, [if steel was very cheap or
free, of course I would use more of it].
So let's start with 100 billion tons of rock and say a million tons of
steel.
Rock costs 10 billion and steel 1 billion dollars. Say the rocks
average density is 1, in volume that's 100 billion cubic meters. A km
cube is a billion cubic meters, this could have 1 km sq by 400 km
long. Now, let's see, a million tons of steel will make 3215 km of 3'
diameter 1/2" thick pipe, so with 4 to side you use up 1600 km. The
other half of this steel can be used for ends and misc stuff. This
"cage" for rocks which is 100 km long would have enough mass to have
some gravity. Now if you had two these "caged rocks" say 600 km apart,
they would slowly move towards each other because of their
gravitational attraction. Now suppose these structures were held
together with cables, starting with cable length which was 1000 km
long, so that in the middle of this 1000 km cable was at GEOstationary
distance- one cage is 500 km nearer Earth from GEO [& other 500 km
further away]. Now, this only about 1/80th the distance towards Earth,
so let's say it's weight is "about" 1%- but of course 1% of 100
billion is still a billion tons of force [lots]. Now shorten the cable
length so your cage is only 250 km towards earth [from GEO], now you
are only about 1/160th of distance- with say about .6 billion tons of
force & the gravitition force from the other "cage" might be becoming
more significant at only 500 km apart- but it's doubtful it would be
anywhere close to .6 billion tons of force. Half the distance again,
so now you have about a 1/3 billion tons at 250 km apart [1/320th
distance to Earth]. Hmm, the mass of both these caged rocks is about
the same as the Asteroid Eros and "Depending on where they stood on
Eros, a person who weighed 200 pounds (90 kilograms) on Earth would
weigh about two ounces on the asteroid."
http://near.jhuapl.edu/intro/faq.html
So that's 1600th of Earth's gravity, so both 100 billion ton cages
would attract toward one another with force of about 1/8th of a
billion tons. So half the distance once again, so they are 125 km
apart and you are somewhere close to where you want to be. So both
cages are 62 1/2 km from geostationary. If the outer cage is put about
100km further away it will it will provide around 1/3 billion tons of
force and if nearer cage is pulled closer to the geostationary and the
other cage then you can get about a up to 1/8 of billion tons of force
without needing any tension strength.
So, lets start with a pile of rocks with same mass a Eros- about 20
km in diameter sphere. This will be at Geostationary distance. Through
this pile rocks you will 4 pipes which have length of 100 km- 6'
diameter with 4" walls weighing in total million tons, the "cages"
will be attached to these pipes and be able to move the cages closer
or further away from the "rock pile". Instead one cage at either end
of these poles, there will four cages, so it's 2 km sq by 100 km. With
all this mass I think should have gravity force of at least 1000th of
Earth's at end of cage in which I'll start attaching cable which leads
to Earth. The cable will be a pipe, say 64 6' pipe which are 1/2"
walls which 25 km long and these 64 pipes are formed into a single
pipe which is about 120' (40 meters) in diameter, this steel weighs
about 1 million tons and has a volume of about 1256 cubic meter per
meter of length- 1,256,000 cu meter per km of length, this large pipe
is filled with material which result in an average density of 1 or
more & fill up to say the 20 km level, giving about 25 million ton of
weight- of course, since it only has 1/1000th the gravity this is only
25 thousand tons of force. That not enough, I want tens of million of
tons at least. So let make the pipe which 40 meter in diameter be just
one pipe of an even bigger pipe which has 64 of these 40 meter pipes,
giving a diameter of about 815 meter. Plus put one 40 meter diameter
in the middle. So we have 65 times 25 thousand giving 1.6 million,
plus we fill in the big pipe up to 20 kilometer, the big pipe gives
about 1/2 million cu meter per meter of length, so that's an
additional 10 million tons. So in the 1/1000th of Earth gravity we get
a total of about 12 million tons of force. Probably not enough, but
I'm tired of doing this. So far I've spent about 70 billion just for
steel, and zillions for rock.
Sigh.

John Ordover wrote:
However, tethers might well hit that last limit, with a mature system,
and plenty of throughput.

...as long as you have a large supply of unobtainium around.

There is a big difference between sorts of unobtanium.

Some sorts just look practically impossible, for example 'scrith' in
Larry Nivens 'Ringworld' which forms the structure for a rotating ring
around a star with a huge land area and trillions of living creatures - it
requires strength around 10^20 times that of any known material.

Ask anyone in 1840 if it might be a good idea to make a bridge out of
aluminium, and they won't stop giggling, as it costs more than gold to
produce.

However, they will probably agree that it could physically be done if
someone were to manage to drop the price by several orders of magnitude.

Structural uses of nanotubes are small lab-scale, they are available at
exhorbitant prices, and are not very well understood.

It's not that unlikely that a grad student, armed with some really good quality
drugs, couldn't come up with some way of making long 100GPa threads tomorrow.

It's probably more likely that it will gradually happen, with strengths and
lengths climbing as the years go by.
This is a young field, where there probably are areas that someones overlooked
until now.

--
http://inquisitor.i.am/ | | Ian Stirling.
---------------------------+-------------------------+--------------------------
"Give a man a fire, and he's warm for a day. Set him on fire, and he's warm
for the rest of his life" -- Terry Pratchett-Jingo

John Ordover wrote:

I agree with your last statement. But. NASA, the guv'mint, and the
big corporations have a lock on space - and for various and sundry
reasons they aren't going to give it up. Think of the SE as a means
to side step The Man and deliver CATS without their quite realizing
what's going on ....

and again, this plan only works if you have materials that don't
exist, and a market for going to space via elevator that doesn't
exist.

And, somehow the NASA, the guv'mint, and the big corporations
miss that huge, multi-billion (trillion?) dollar development. Just who
does the money come from?

In this case I believe that John Ordover may be an optimist.

Mike Walsh

Michael Walsh wrote in message ...
John Ordover wrote:

I agree with your last statement. But. NASA, the guv'mint, and the
big corporations have a lock on space - and for various and sundry
reasons they aren't going to give it up. Think of the SE as a means
to side step The Man and deliver CATS without their quite realizing
what's going on ....

and again, this plan only works if you have materials that don't
exist, and a market for going to space via elevator that doesn't
exist.

And, somehow the NASA, the guv'mint, and the big corporations
miss that huge, multi-billion (trillion?) dollar development. Just who
does the money come from?

In this case I believe that John Ordover may be an optimist.

Mike Walsh

Althoug I disagree with John with respect to the need for
advanced technology for a near-term space transport capable
of frequent, reliable low-cost transport to LEO, I have
to agree with both of you with respect to the current
economic environment for commercial development of a
space transport.

That is why I insist that the first commercial space
transports must be brought on line for an investment
of no more than $200 million--and perhaps the limit
may be more like $100 million. I view this investment
limit as a requirement every bit as basic as the
delta-vee requirement. Where I part company with both
of you is that I truly believe that it is possible
to meet this investment requirement with current
technology. It does require getting the money somehow
without resorting to a DOA type of management that
precludes good system concept design. And that is tough.

Best regards,
Len (Cormier)
PanAero, Inc. and Third Millennium Aerospace, Inc.
( http://www.tour2space.com )

Michael Walsh wrote in message ...
John Ordover wrote:

I agree with your last statement. But. NASA, the guv'mint, and the
big corporations have a lock on space - and for various and sundry
reasons they aren't going to give it up. Think of the SE as a means
to side step The Man and deliver CATS without their quite realizing
what's going on ....

and again, this plan only works if you have materials that don't
exist, and a market for going to space via elevator that doesn't
exist.

And, somehow the NASA, the guv'mint, and the big corporations
miss that huge, multi-billion (trillion?) dollar development. Just who
does the money come from?

In this case I believe that John Ordover may be an optimist.

Mike Walsh

I don't think he is, at least regarding this point. As for
development money .. Michael Laine of Liftport reckons he can bring
one in for only $10 billion. That's not lunch money, but it's not a
lot, compared to the cost of building a new power plant, or an M1
tank, or the cost of deploying a brigade of Marines overseas for six
months.

~er