Dr. Bryan Laubscher On The Space Elevator, Sunday, 9-12-10
Guest: Dr. Bryan Laubscher. Topics: A comprehensive look at the space elevator. Please note that you are invited to comment, ask questions, and rate this program on the new Space Show blog, http://thespaceshowoutsidethebox.blogspot.com/. We welcomed back to the program Dr. Bryan Laubscher to update us on the recent space elevator conference and happenings within this industry. This is a two hour forty-five minute program with lots of listener questions and challenges, both by email and using the toll free line. The program is divided into two segments, the first segment lasting for about the first hour. General themes were present throughout the program so rather than breaking the show down by segment, I will tell you what we discussed. We were updated with developments from this year's conference. We learned about special conference guests Yuri Artsutanov and Jerome Pearson, the incredible climber contest and more. Visit The Space Elevator blog for more information, http://www.spaceelevatorblog.com/. Also visit the website for the Spaceward Foundation at http://www.spaceward.org/ and the site for the International Space Elevator Consortium (ISEC) at http://www.isec.info/. Discussion topics covered the progress made with the NASA Challenge climber contest, the thermal conductivity of carbon nanotubes, the markets for carbon nanotubes, and eventually the economics of the space elevator. Scattered throughout these discussions, Jack asked about Professor Richard A. Muller at Berkeley who has advanced the theory that we are residing in a binary star system with a red or brown dwarf that may, at some point, push asteroids from the Oort Cloud into the inner solar system. Do not miss what Bryan had to say about this. We talked about nuclear propulsion and alternatives to chemical rockets. The economics of the space elevator were challenged by several listeners in hard hitting phone calls during the second segment. As the transcontinental railroad was brought up, I referred everyone to last Friday's program with Berin Szoka and the economic paper he recommended we read on the transcontinental railroad at http://fee.org/nff/the-myth-of-the-robber-barons. The discussion evolved with multiple callers about launch rates, Falcon launchers and Space X, launch costs and their drivers, markets, and the future for the elevator. Sparks flew among Kelly, Charles, and Bryan! At one point John joined the callers to provide current Falcon launch costs from the Space X website and to opine on the value of space elevator research which was under attack by some of the listeners. Other problems were discussed re the elevator, specifically lightening strikes, orbital issues, and payloads. I realize this is a longer than usual Space Show program, even longer than most shows that run to two hours or slightly longer, but it is an important, must hear program and we thank Dr. Laubscher for staying with us to be responsive to the listeners. At the end of the show, propellant depots were put into the mix by John in Atlanta and in responding to John, Bryan also talked about elevator orbits and how the elevator puts a payload in LEO. The book, "The Space Elevator," will be on the OGLF Amazon book partners page later this week, www.onegiantleapfoundation.org/books. If you have a question or comment for Dr. Bryan Laubscher, please send it to me at drspace@thespaceshow.com and I'll forward it to him. Don't forget you can post your comments on the blog address above and I will make sure Bryan sees them.
As one of the folks who called in to question the economics of space elevator. My point was, even if you give space elevator spectacular leeps in nanofiber cables (hundreds to thousands of times more strength, while still getting a hundred fold lower cost per pound) and assume 100 fold increas in market demand for launch (so the cable is lifting the its maximum lift capacity per year), and assume there is no other costs over 40 years other then the cost of the cable material (no construction or operation costs OF ANY KIND, nor any development costs of any kind except that you need to make the cable) --- and I really think these are REALLY generous assumptions for space elevator -- space elevators are STILL not cost competitive on a pound to orbit sense, with current rockets at current market size!! At best they are slightly cheaper then some current offers under current real world conditions..
ReplyDeletePast that his numbers for cost of ships, confusing efficiency numbers with cost numbers etc of rocket launchers just fall into the noise.
Its just much much harder to lower costs with something like a space elevator, then with chemical rockets, much less other more conventional -- and vastly cheaper -- launch vehicle technologies. So I just can't grasp why the guest and others are so into space elevators. Wish fulfillment I guess. Also the idea of a elevator to space sounds super cool.
Oh well.
For some context, about 4 years ago Michael Laine from Lift port had come onto the space show and discused Liftports idea for commercially developing a space elevator with nano fiber composite cables. They expected to need about 20 million cubic meters of nano composite to make a space elevator that could lift 2,000 tons of cargo a year (I think that's nearly all the tonage of cargo humans have put into space in all history).
ReplyDeleteSo the first issue is what does 20 million cubic meters of nano composite cost?
(liftport assumed $2 billion for complete construction costs)
Poking around today I found:
http://www.nanomaterialstore.com/
Carbon Nanotubes 5 grams for $100. Great Quality. Prices Can't be Beat! Visit Today
http://www.buckeyecomposites.com/
Buckeye Composites’ carbon nanomembrane, or “buckypaper,” is a thin, paper-like membrane of carbon nanotubes, nanofiber, nanoplatelets and/or other carbon nanomaterial. Buckypaper can be comprised of 100% carbon nanomaterial or can be pre-impregnated or “pre-pregged” with resin.
Neat article on nano fibers is:
http://nextbigfuture.com/2009/10/carbon-nanotubes-costs-strength-and.html
>>
When people think about building things with carbon nanotubes or with carbon nanotube enhanced materials they need to know that there is not much production of carbon nanotubes. There is less than 1000 tons/year of carbon nanotubes being produced and most of that is in a form that is like an unsorted powder. The material that has been woven into threads or sheets will soon be tens of tons per year and that macro scale material is not as strong at the macroscale. The cost of material increases as you require higher purity or a particular form of it.
Even material like Kevlar and regular carbon fiber is produced at the 10,000 ton to 100,000 ton per year level. Global raw steel is produced at about 1.2 billion tons per year and cement is at 2.6 billion tons per year.
<<
So it would take decades to centuries to make enough kevlar to equal 20M tons (course the composite cables would be made up of a lot of binding agent).
The article lists strength per kilo and cost per kilo.
Kevlar costs $4,500 per ton, or $90 billion if you bought as much tonage as needed in nano fiber for the space elevator cable
Graphite costs $7,000 per ton, or $140 billion if you bought as much tonage as needed in nano fiber for the space elevator cable
Spectra costs $12,000 per ton, or $240 billion if you bought as much tonage as needed in nano fiber for the space elevator cable
Carbon nanotube POWDER now cost $45,000-$150,000 per ton, or up to $3 Trillion if you bought as much tonage as needed for the space elevator cable - course we don't make anything like enough, and structural fiber nanotubes cost vastly more then this now.
If you assume the cables last 40 years, and lift 2,000 tons per year, that's 160 million pounds over 40 years. If you only consider $160 billion in total cost for the cables construction and operation for those 40 years (I.E. basically you only consider the cost of the fiber to build the cable, assuming a staggering cost reduction in nanofiber manufacturing costs) you get $1,000 a pound to orbit -- and its the wrong orbit.
Musk was offering to get lift cost well bellow that if he could get a couple hundred tons of business a year with his current Falcon rockets if he could get a couple hundred tons of business a year not a couple thousand. Oh and he spent a couple hundred million to develop his company and craft, not hundreds of billions.
Space elevator spends a huge amount of money, and assumes several major technological and scientific breakthrough -- and huge international political and market breakthroughs -- just to equal current lift performance of old style rocket launch craft.
Based on the numbers Kelly is using, the space elevator would require transporting 20,000,000 tons of material plus the counterweight to GEO in order to lift 80,000 tons of cargo over a projected 40 year life cycle at a rate of 2,000 tons per year. But, the 20,000,000 tons plus of material would have to orbited in the type of rockets that the elevator is supposed to replace. It would naturally be cheaper to just orbit the 80,000 tons of payload with rockets. That is 4/10 of a percent of the total just for the cable not counting the counter weight.
ReplyDeleteThat seems to shoot the whole idea down unless Kelly basic numbers are way off.
Good point John.
ReplyDeleteA nit, but the 20,000,000 cubic meters was the liftport numbers; though given your talking tens of thousands of miles of cable, most get similar numbers.
Lift port talked about just lifting enough to start a system where they lift the rest via the starter cable. Not real plausible given such a huge fraction of the cable would be high near geosync.
I just thought of something. You can't lift even 10's of thousands of tons in any reasonable time with current launchers. So to build a space elevator, you would first need to field a very high capacity RLV rocket system, and operate it on a scale to drive its per pound to orbit costs to a tiny fraction of current launch costs -- which means by trying to build a space elevator you first must build a rocket based system that inevitably would provide lift costs orders of magnitude cheaper then the space elevator ever can.
ReplyDeleteOr, if you ignore all the industrial and scientific analysis of what drives costs, and assume rockets are incapable of providing any lower lift costs. Lifting the total 20 million tons to orbit at a $1,000 a pound. Would cost $40 trillion dollars!
The cost of launch has nothing to do with technology. The cost of launch is all about economics.
ReplyDeleteTo give you an idea of how low the price could be: a Falcon 9 launch, 10,450kg to LEO, is only about $50k in fuel. This has no relation to the price, $56M, has no relationship. It is set based on an expectation of how many launches are actually *wanted* in a given year and how much the competitors are charging.
So, let's say you could magically zap into existence a space elevator, and the actual costs were $20/kg to LEO, what price would you set to carry payload to orbit? If it's anything significantly lower than $5000/kg then you're going to get kicked out of your company by your investors because you're not making good business sense.
New technologies do not lower prices - competition does. In order to lower launch prices with a space elevator you'd need more than one of them, and a motive to compete for launches. Even then, there's likely a market saturation point where it makes no sense to cut into your margin.
The alternative is some form of regulation or other non-free-market approach.
If you want to lower launch prices, the answer is easy.. I know plenty of people have said this, and I'm sure you've heard it all before, but the answer, to me, really is simple..
Increase launch demand. Develop payloads that people want to launch, and get more people interested in launching them. Getting rid of stupid legislative blockage to that is the first step.
> QuantumG said...
ReplyDelete> The cost of launch has nothing to do with
> technology. The cost of launch is all about
> economics. ===
Yes and no. It is about economics - but not the ones you mention. Even if a seller wanted to dump on the market to spike demand adn grow the market dramatically (which has worked very well for a lot of companies with new technology spawning new markets), there currently is virtually NO market. Globally a couple dozen launches a year, and declining strongly. When it a billion or 3 in start up and overhead to do a decent launch system?
> New technologies do not lower prices - competition does. ..
Again yes and no. Obviously new technology allows lower margin costs etc. But in space launch now none of those impact launch costs. Competition can lower costs - but if the market size is so small no one can even cover their overhead, they can't lower their costs. In cases like this adding more competitors just means excess unused capacity (read overhead costs) the to small marker has to carry. Resulting in increased costs, not lowered costs.
> Increase launch demand. ..
Big agree. We have all the technology we need to support far lower launch costs (even hundreds of times lower) but you need a BIG market. Aviation quickly developed one - and they didn't need to start with the equivalent of trans pacific range aircraft. Space hasn't found one, and at the moment is losing its old markets.
The space elevator concept has always been interesting. It looks a lot further in the future that I ever thought.
ReplyDelete>Terry Pickett said...
ReplyDelete> The space elevator concept has always been interesting.
> It looks a lot further in the future that I ever thought.
??
Really it looks like it could never, with any technology, be competitive. Any history with the capacity to build it - would have to have already implemented a systems vastly more flexible and economical then the space elevator ever could be.
Regarding a comment on the space elevator that occurred during an Open Lines:
ReplyDeleteA caller had said that the elevator could not work unless all satellites below GEO were cleared/removed because some large object was bound to intercept the elevator eventually and destroy it. David said that he thought the elevator was placed at some spot along the equator to avoid the other satellites.
I was impressed by the caller's comment because that had not occurred to me before. It did not seem quite right to me that there was a safe spot for the elevator based on this concern. I knew about the micrometeorite and orbital debris problem and the need for shielding the elevator cable, but no amount of shielding can block a rocket body coming at high speed directly at the cable.
It boils down to satellite orbital precession, which is the movement of the orbital plane around Earth. Its due to the non spherical nature of a spinning body which creates a non spherical gravitational field. Some satellites can stay in the same orbit plane, but most do not. This alone is enough to know that eventually a large object would hit the elevator.
Rather than derive equations to show this, I ran the free version of Satellite Tool Kit. I downloaded the orbital elements for ISS for a year, created a space elevator facility at the equator, constrained the access to the ISS to be within .5 degree of zenith (89.5-90 deg elevation), and ran STK to find the access to ISS over the entire year. Of course, ISS does pass at least once near the elevator.
Now, even .5 degrees is a big miss, so you can adjust the longitude of the facility and lo and behold eventually you will find a longitude to get ISS to collide with the elevator. OR, you can run the analysis for more years OR with all large orbiting objects (there are at least 3600 objects > 1 square meter in size presently in orbit, and ~850 >10 square meters). Eventually, for any equatorial tether location (and no other ones work for the elevator because it has to reach to GEO), a large object will intercept the elevator.
With ISS, you might be able to fire engines to avoid the tether (slowing it down or speeding it up), but there are a lot of satellites that are without orbit control (spent rocket boosts, large debris, even small passive satellites) so they can't take evasive action.
The elevator can't move or bend to avoid the object (its under a lot of stress and weighs a lot). I don't see any way around this problem!
Regarding a comment on the space elevator that occurred during an Open Lines:
ReplyDeleteA caller had said that the elevator could not work unless all satellites below GEO were cleared/removed because some large object was bound to intercept the elevator eventually and destroy it. David said that he thought the elevator was placed at some spot along the equator to avoid the other satellites.
I was impressed by the caller's comment because that had not occurred to me before. It did not seem quite right to me that there was a safe spot for the elevator based on this concern. I knew about the micrometeorite and orbital debris problem and the need for shielding the elevator cable, but no amount of shielding can block a rocket body coming at high speed directly at the cable.
It boils down to satellite orbital precession, which is the movement of the orbital plane around Earth. Its due to the non spherical nature of a spinning body which creates a non spherical gravitational field. Some satellites can stay in the same orbit plane, but most do not. This alone is enough to know that eventually a large object would hit the elevator.
Rather than derive equations to show this, I ran the free version of Satellite Tool Kit. I downloaded the orbital elements for ISS for a year, created a space elevator facility at the equator, constrained the access to the ISS to be within .5 degree of zenith (89.5-90 deg elevation), and ran STK to find the access to ISS over the entire year. Of course, ISS does pass at least once near the elevator.
Now, even .5 degrees is a big miss, so you can adjust the longitude of the facility and lo and behold eventually you will find a longitude to get ISS to collide with the elevator. OR, you can run the analysis for more years OR with all large orbiting objects (there are at least 3600 objects > 1 square meter in size presently in orbit, and ~850 >10 square meters). Eventually, for any equatorial tether location (and no other ones work for the elevator because it has to reach to GEO), a large object will intercept the elevator.
With ISS, you might be able to fire engines to avoid the tether (slowing it down or speeding it up), but there are a lot of satellites that are without orbit control (spent rocket boosts, large debris, even small passive satellites) so they can't take evasive action.
The elevator can't move or bend to avoid the object (its under a lot of stress and weighs a lot). I don't see any way around this problem!
I thank Kelly,John, QuantumG, Terry and Anonymous for their thoughtful comments. The Space Elevator represents such a paradigm shift that its many issues and considerations are vast.
ReplyDeleteI request that these interested individuals read The Space Elevator book by Edwards and Westling. That book lays out the conceptual design that almost everyone is following. The book is a "first-cut" at the problem. Solutions for many of the issues are developed in the book. The book is not the last word on the Space Elevator or its design, but it presents a baseline from which the discussion can be conducted. Many assumptions are made in the book, and those need to be reviewed and challenged.
If we do not have a basis for discussion, we'll simply continue to throw out numbers to each other.
By the way, there are many analyses that could be presented as papers at the annual Space Elevator Conference in Redmond, WA. That is the best forum in which to hold these discussions.
Thank you,
Bryan
I will have to take a look at that book.
ReplyDeleteI did look at the "The Space Elevator NIAC Phase II Final Report" and surprisingly they addressed the LEO impact issue this way...
"Orbital objects have always been a concern. We calculated that a large orbital object, satellite or debris, would strike the space elevator at least once a year if nothing were done to prevent it.
This problem is currently of concern because our legal study has stated that we will not be allowed to construct the space elevator unless we can demonstrate that it will not get in the way
of existing, operational satellites.
We have gone through a complete calculation on the likelihood of an orbital collision and found
tracking systems that can warn us of an impact days to week ahead of time and a system for
moving the ribbon to avoid the collision."
So they thought they could MOVE the ribbon!!! By moving the elevator Earth platform (in the ocean). I would like to see the calculations for that operation!
Really Bryan I think its much less complicated question then your thinking. It’s the old argument of river ferries vrs a bridge. A major bridge might cost thousands of times more then the ferries, and require similar maintenance costs – but be capable of carrying vastly more vehicles and tonnage per hour, be easier to operate in bad weather, and require similar maintenance costs. I.E. lower total cost per-ton and vastly more capability.
ReplyDeleteFor a space elevator however all this gets reversed, and you need to assume VAST improvements in science and technology just to be competitive. Again briefly:
- you must assume million fold improvements in production costs for NANO fibers
- while increasing the length of the fibers from millimeters to meter – kilometer length
- while developing new technologies to cross bind the nano-fibers into usable cable approaching a fraction of the strength of the fibers.
- then you need to deal with issues of radiation protection of cable cargo and personnel from normal and van-Allen belt radiation.
- then deal with lightning, electrical issues between the earth magnetosphere and earths surface.
- then deal with operational issues of running cable cars up and down the cables, avoiding collisions with things in orbit, etc.
All the above major technological and scientific advances, and a hundred fold increase in market size – only allows the cable to become roughly competitive in cost with current launch vehicles. Not dramatically better, but comparable in costs. Worse the lifts needed to lift a tiny fraction of the cable and otherwise support construction of the cable, due to simple economies of scale economics, drive down costs of normal chemical rocket based launchers by a factor of hundreds, to a thousand.
So if it takes these vast improvements to make a space elevator merely competitive with current launch vehicles costs, while being much less flexible or adaptable. (The space elevator takes everything to the same pointing geo, or drops it into the equatorial plane, but most things sent into orbits go into very different orbits. Also different ships can be boosted closer to the client, adapted to the cargo.) What’s the point? Obviously far simpler technology development could dramatically improve rockets performance and cost effectiveness. (ramjet/rocket hybrid launchers, laser powered rockets, etc)
More detailed analysis of the elevator concept could refine this and make some improvements, but when you’re billions of times behind, and minor improvement of rockets would drive their margin costs near basic energy costs of the changes of kinetic and potential energy any system must supply to put something in orbit. There just isn’t any great potential advantage the space elevator could ever tap.
So the space elevator seems at all angle to be a tremendously complex and expensive system, to do what conventional or upgrades rocket craft can do vastly simpler, cheaper, and more safely and flexibly.
Its not a revolutionary pardyme changing technology. Its merely a complex and expensive uncompetitive concept.