Comments on Liftport’s space elevator work

This response to earlier comments was left on the post about Liftport’s space elevator development work from a few weeks back, and I wanted to toss them up so they weren’t overlooked. (Earlier comments in bold.)

And that means getting beyond our primitive space technology.

Maybe not.

In terms of material needed we can – we think – get the job done with six to eight Delta IV launches, plus on-orbit assembly.

The last is tricky – it’s not like anyone has done this before … unless you count ISS and MIR. We’ll need a place for the assemblers to work and live. Again, it’s a new application of somewhat established concepts. But it’s been done before.

This is not to poo-poo the difficulty involved, merely to note that it’s possible with technology we have now.

People would want to see that a beanstalk works, and continues to work for a significant period of time before allowing a 100000km carbon nanotube whip to be placed over their heads

Wrong imagery. Any forces that would impart enough energy to play crack-the-whip will shred the material. The stuff is going to be strong, but that level of strong it ain’t.

A break? Stuff that is below the break will come down. Stuff above goes up and might be controllable in it’s altitude by moving the cars up and down.

The stuff coming down? It’s light – kg’s per kilometer. It’s messy and there are (maybe) some long-term implications if we don’t police up the stuff. And if the break is way up there and we have thousands of kilometers coming down? The bits that survive the shock of the breakup will burn on re-entry.

Which is not to make light of any of this – we’ve got studying to do before we can say with assurance ‘yes we can do this’ but some basic physics and engineering dictate that a whip hovering over our heads it’s not going to be.

More seriously and of longer-term impact – we’ve got to live here too. We’re working hard not to build something that could wrack the planet. Many eye-balls help – and I hope you and other bloggers like you will keep an eye on us and keep us honest.

Enron I don’t want to be.

A lot of good discussion on that post if you’re interested in such things…

Comments

  1. Kim Stanley Robinson’s Red Mars (or was it Blue Mars) has a good piece on an elevator coming down. Wouldn’t want to be under it when it did…

  2. Red Mars it was. Yeah, potential for quite the ‘natural’ disaster, or prime terrorist target Not that I’m not all *FOR* the space elevator, mind you.

  3. The stuff coming down would probably be razor sharp. A hell of a clean-up. If the break was low, most stuff would go up as the big counterweight (probably a nuclear reactor) spun out of orbit. I believe the space shuttles may perfect for ferrying materials into orbit for assembly. As soon as the first beanstalk is done, the shuttles are obsolete junk. Beanstalks would have some other profoud affects: 1. It would become easy to put heavy weapons in space. 2. Space mining and manufacturing instantly become physicaly and financialy viable industries. 3. Nuclear power becomes more attractive. Want to get rid of the waste? Run it up the beanstalk and push it towards the sun. 4. Real spaceships can be built for movement from high Earth orbit to other planetary bodies.

  4. I’m with August the possible benifits would be revolutionary across the board. History from the first successful lift on would be changed on a level supasing the first ocean going boats creation. Everything from massive space mining of the asteroid belts to major colinization of the planets (think elevators on mars or Europa). Wow would be the word. As for the risk look at that like this. First off how many power lines do we drive or walk under daily? By that I mean we are talking about a rather thin wire that even if it fell would effect a small line that unless it literally landed on your head you would be scared but OK wipping well earned sweat off your forehead. The terrorist threat? I imagine the security would be extremely high and again we are talking about a rather thin wire. I would hate to see the Jihadi that attempted to ram the line with a airplane (short a nose impact it would most likly just cut the wing off the plane but survive). Remember this stuff is supposed to be insanely strong. I would say the possible gains way way way out weigh the worst case senerio’s.

  5. You can talk about this idea all you want, but until it is technically feasible, it is nothing more than science fiction. If you want to talk about a realistic method of getting to low Earth orbit, I was working at Boeing’s Kent Space Center when they were patenting this idea. As far as I’m concerned, the shuttle is already obsolete junk. The only thing worse is what NASA is planning next.

  6. Defens – Interesting article. At least it provides a reason for that special hanger built in Guam. That said, the boron based fuel makes me suspicious. Typically craft like this would dual use the fuel as a power source and coolant. As described, I see all sorts of issues. I would not be surprised if that was disinformation. I would expect a methane based fuel. Fundingwise, is very typical for contractors to cross fund programs, so I can easily see how they could bury the funds.

  7. Dfens, Is it the cable technology or something else that makes the elevator not feasible at this time? To my non-engineer mind, the rest of the design appears to be current technology.

  8. Yes, it is the fact that there is no material strong enough to physically build this elevator is the problem. This group is very up-front about that issue, to their credit. Still, I find myself somewhat annoyed by the fact that someone would spend money on an unfeasible project when there are so many that are feasible. Some are very cutting edge like laser or microwave powered vehicles. I suppose I shouldn’t take it personnally. I mean, at least ideas like this do get people interested in space. I enjoyed reading the science fiction book that first postulated this idea. I wish I could remember the name of it. It started from the premise that the materials problem had been solved. I was either in grade school or junior high when I read it, so it’s been a while.

  9. Dfens It’s all about Payload Payload Payload If that’s IF the space elevator can get going it would revolutionize space exploration more so that even the first ocean sailing ship revolutionized history from that point on. We would be looking at exploration of the solar system, mining of the asteroid belt moon ect, colonies, ect all in a massive push because of the slashing of the cost a space elevator would deliver day 1. The problem with a space plane is the payload will be minimal and cost of fuel and vehicle will stay high. Space plane may fit as a bomber type vehicle but it will not fill the exploration needs. It will be no different than the current Shuttle they both will waist huge amounts of their limited payload on toting wings, flaps, tail, heat tiles, ect.. all of which look cool and are great for atmospheric flight but in 0 gravity space its just useless. I think the future will be a combo the shuttle tank/boosters with the shuttle replaced with the ALL payload and a smaller old school reentry vehicle tipped ballistic missile type launcher send the crews up behind the payload sections. http://www.space.com/spacenews/businessmonday_060320.html A shuttle heavy lifter is estimated to be able to push 100+ tons into orbit for space vehicles that are monstrous. We would be talking single stage launch for moon missions with all supplies inside. One thing I have not seen no one talking about (maybe fear of being accused of putting the cart before horse) but that is an actual space exploration vehicle. Why relaunch the whole damm space travel part of the vehicle the 0 gravity living section and the space boosters every mission. We should build a space station type structure with some boosters on it attach a moon/mars/europa lander to it after we launch it, another launch could refill the tanks with fuel and supplies, another launch deploy the crew and take back the old crew. Going up in orbit and coming back is useless. If we can’t go to the moon, mars, Europa, asteroid belt and kick rocks discover map find Explore we are just wasting money, time and effort.

  10. I wonder if they could build a half beanstalk. Put a platform in LEO and have the elevetor extend from there to HEO. Security would be better, you launch your cargo vehicle up to LEO, drop off the payload and then run it up to HEO. Just a thought

  11. It was probably ‘The Fountains of Paradise’ by Arthur C. Clarke. I read it while in Sri Lanka (where the story takes place). He changes geography a little to fit the story but it is a good book. Larry Niven and Greg Bear have also used beanstalks in their stories.

  12. Coolhand, that idea has been put forward – they call it the rotovator. You have a tether rotating about its center of mass, which is in orbit around the Earth. It’s rotating such that when a tip comes down, it’s moving against the rotation of the earth. (I think that’s right) You launch a suborbital shot, it goes up, hooks on to the tether and is hauled up to the center. Likewise, things can be lowered, and dropped. If your vehicle misses or aborts on the grab, it just goes back to earth for a runway landing. For incoming traffic, the speed when they’re dropped is relatively low, so they don’t have to undergo harsh normal reentry. You could use Rutan style vehicles, without high tech ceramic coatings and what not. The rotovator would be cheaper to construct because it wouldn’t require either the high strength of a regular beanstalk, or the difficulty of anchoring it.

  13. Thanks, Bram. That was it, because I remember it being set in Sri Lanka. C-Low, you really don’t quite understand the 2 stage to orbit concept they are talking about in that article. The vehicle they describe is an XB-70 like aircraft that carries a rocket to Mach 3 then drops it. In this particular case, they dropped a manned vehicle with wings (allegedly) but the 2nd stage can be nothing more than a pointy ended cargo tube with a rocket engine on the back. That was the original Boeing concept. The cost is very low because the fuel for the first stage is regular jet fuel. The oxidizer is supplied by the Earth’s atmosphere. The mission is very short. You go up, accelerate to Mach 3, drop, come home, reload, repeat. You could launch several payloads to low Earth orbit per day. It would only be a little more complicated than loading bombs onto an F-15. As for some of these other concepts like laser or microwave powered ‘beamed energy’ vehicles, these are almost as inexpensive as a space elevator. Even with a space elevator you still have to accelerate the payload to 18,000 mph. You don’t get that for free. It takes the same amount of energy to accelerate 100,000 lbs to 18,000 mph regardless of how you do it. The efficiency advantage the elevator has is that you can get the energy back from the container that takes the payload to LEO. With a ground powered laser or microwave vehicle, there would still be an energy loss in the vehicle return process. One thing I would like to see is aircraft using beamed energy. Today you fly from one nav beacon to another, but tomorrow you might fly from one microwave beaming station to the next. The compressed air in the engines would be heated by those microwaves instead of by the combustion of kerosene. Given the fact that part of every dollar we spend on oil goes to fund some terrorist psycho in the Middle East, it seems to me this concept would be well worth investigating. It’s better than the maglev train concepts because one cow couldn’t kill a thousand people. An air breathing, beamed energy craft could also be used as a first stage in the 2 stage to orbit approach. Because the air is supplying the reaction mass, the ISP of the engine is infinite for these vehicles. There are a lot of great, and technically feasible options out there.

  14. Coolhand and Buckethead, you realize that your center of gravity has to be at geosynchronous altitude, right? If it isn’t, the air drag would cause it to lose energy and fall out of orbit. Geosynchronous altitude is 22,300 miles. That’s a lot of unobtainium.

  15. Dfens, not according to what I’ve read. You could fly one of these things in a much lower orbit, and if the tips are dipping down only to 65 miles or so, air resistance is not so bad. Significant, but not terrible. Naturally you’d need to expend energy to maintain your orbit. One obvious solution is rockets. But one of the odd properties of long magnetic tethers in an electromagnetic field is that you can pull out electricity and lower your orbit, or pump it in and boost it. A large energy source, like a nuke plant or something, could do most of the work of maintaining a tether in orbit without the use of rockets. So they say.

  16. The lower it is, the faster you have to go to catch up to it and the more energy you have to put in it to keep it from falling out of the sky. Also, even if it is relatively small, you’re still talking about something that is fantastically large by our current space faring standards. I’m not saying it is a bad idea. I’m saying let’s work on other good ideas first. We’ll get to this one eventually, but let’s do what we can now. Ok, sorry about the soap box thing. Those damn Apollo rockets are what got me interested in this biz in the first place. Who’d have dreamed we wouldn’t be doing far better things by now?

  17. Dfens, that’s why you have it rotating against the direction of Earth’s rotation, so it’s going relatively slow when a tip reaches perigee. As I said in my comments to the other post, I think that developing other methods are really a necessary precondition for doing something like this – and, in all likelihood playing with free tethers and maybe a lunar beanstalk (1/6 gravity will make it much easier – we could probably do that with existing technology right now. Assuming of course, that we are able to get to the moon.) There’s lots of possibilities. Once real money starts getting thrown at the problem, without the constricting bureaucracy of NASA, we will probably have several alternatives. Vertical take off SSTOs, HOTOL two stage designs, big boosters, small boosters.

  18. Also, we are a lot closer to solving the materials problem than we were even a decade ago. The CNT and buckeytubes and what not are in the ballpark of required tensile strength and weight. Its not completely unreasonable to suppose that the unobtanium will be developed, because so many people are trying to do it, for reasons that are completely unrelated to the beanstalk. The new carriers are being planned with new technologies that haven’t yet been invented – especially in regard to weapons and information systems. Granted, these aren’t showstopper technologies the way cable materials are for the beanstalk, but still, this kind of thing isn’t exactly unheard of.

  19. Materials? There’s a very productive spider in my yard that can probably help out in that department.

  20. I worked on NASA’s High Speed Civil Transport program. They always blamed the materials for the failure to produce a vehicle out of that program too. If they could just come up with the right high temperature composite then their inane aircraft designs would fly right off the drawing board. We wasted almost as many of your tax dollars as that dumbass X-33 did, which again failed because – oh guess what – composites hold cryo-fuels like a sieve. Of course, even if they had held the fuel, the damn thing would have been a colossal failure because single stage to orbit is such a bad idea to begin with. Now call me old fashioned, but I tend to like to figure out if something is feasible up front, before the money is spent. Not later on. If something is not feasible, it’s not feasible. It’s not ‘almost feasible’. Engineering never includes the phrase: ‘then a miracle happens and…’ To be honest, I really find that notion to be rather insulting even if I have used it to pay rent in the past. I guess I’m just a engiwhore.

  21. In their defense, they don’t say that they can build it now – they’re developing the technologies that will lead to a real beanstalk. The Wright Brothers built many gliders before they got to the Flyer – but it was clear what their goal with. If you had interrogated them in 1902, they would have said, ‘and then a miracle occurs…’ Yet, they finally did build a plane. If Liftport figures out ribbon construction and deployment methods, figures out how to build crawlers that can ascend and descend that ribbon, does environmental impact studies and all that, well then they are well prepared to build a beanstalk when the final piece falls into place. And, better, they aren’t spending taxpayer money.

  22. Bram If the break was low, most stuff would go up as the big counterweight (probably a nuclear reactor) spun out of orbit. Where did the nuclear reactor come from? There is no requirement at this time for a reactor at the top end. Or even a counterweight as you’re talking about. The ribbon we propose is 100,000 km long and that _is_ the counterweight Bram I believe the space shuttles may perfect for ferrying materials into orbit for assembly. As soon as the first beanstalk is done, the shuttles are obsolete junk. Shuttle is going away and won’t be available for the job, but I catch your broad meaning. But, no, the first elevator will not obsolete conventional launch solutions. A space elevator will always be slow. For certain applications only a conventional rocket will do. They won’t go away, they’ll become competitive and specialized. Dfens Yes, it is the fact that there is no material strong enough to physically build this elevator is the problem. This group is very up-front about that issue, to their credit. Still, I find myself somewhat annoyed by the fact that someone would spend money on an unfeasible project when there are so many that are feasible. Thanks – we’ve a long established policy to be up front about everything we do. In this case it’s paying off with a measure of your trust, and that’s important. As for money – we’re a rich society. We can afford to spend X billions of dollars yearly on pizza _and_ fund research. We can buy high tech hospital equipment AND put an X-Box in every house. At any rate, we’re not going to be spending seriuos money until it is feasible. The money spent to date is pretty small compared to some projects. Buckethead And, better, they aren’t spending taxpayer money Not much at least. We’re not proud – if Uncle Sugar wants to cut us a check, we’ll take it. We don’t claim that we _can_ get it done without government help – that’s just foolish talk. There is a lot of grant money out there – we apply for it. Some cadets at the Air Force Acadamy worked with us for a class project last year – their time cost y’all something. The point being that the government is an indispensable part of the process. The taxpayers are going to be putting something into this. Not as much (or it won’t be built) as if the government was bulding it themselves, but there will be something. And it’s only right. The state is going to benefit from this project (yes, Dfens, if it works) big time from tax revenue and reduced transaction cost to orbit.

  23. Its very possible with the wonders of Materials Sciences and Engineering. Every day, people in this field make great strides in the fields of nano-materials and nano-assembly.

  24. Engineering is not PFM. Sometimes we are wrong and the thing don’t work, but a real engineer never goes into a project knowing it won’t work. That’s something, but not engineering. Of course, as Buckethead points out, they’re not wasting my money. Not like these jerk-off morons. I like this quote: This is hardly the first time NASA has made a big deal over a next-generation spaceship. Since the 1980s, NASA has spent about $4.8 billion on shuttle follow-up ships that never were built, according to the U.S. Government Accountability Office, the independent auditing arm of Congress. $4.8 BILLION with a ‘B’. You taxpayers are such suckers. Who gets screwed over like that and doesn’t even make a wimper of protest? Dumb as the day is long. How about this one: ‘None of these companies know how to cost innovate,’ McCurdy said. ‘They’re basically aerospace divisions that depend on government contracts. Their whole incentive, based on the international space station, is to drive up costs.’ Sorry to have spoiled the ending for you, but isn’t this what I’ve been saying all along? It’s like hiring a contractor to work on your house under a contract that says you’ll pay him his wages (which he gets to set) and reimburse all his costs, and even add a 15% profit on both of those. Then you let him know you’ll be happy to honor that contract for as long and as much as it takes until he’s done. How stupid would you have to be? I’m guessing only those of you who pay taxes would really know. Is this a great country or what?

  25. Oh, and I forgot to mention. NASA even lies to you about the death rate for the shuttle. Last time I worked on that turd the calculated number was 1 failure in 78 launches. The actual number is almost exactly that.