Space elevator
Interesting
OK, so we make this big long (62,000 miles) wire, attach it to something out in the ocean and a satellite in space and then send an "elevator" up it.
Excuse me... *COUGH*Bullshit*COUGH* Sorry...
I know, I know. I'm open minded enough to know that anything is possible but please, a 62,000 mile long piece of wire? Seems like the elevator would still face all the same problems as a conventional rocket, just having a wire to guide it wouldn't help it escape gravity. I'm not near smart enough to comment on this, I know that but I'm gonna take an "I'll believe it when I see it" stance on this one. Let's see, I'm almost 51 so I'll revisit this issue on my 66th birthday.
I know one other thing too, I sure wouldn't want to be around if that sucker broke...
OK, so we make this big long (62,000 miles) wire, attach it to something out in the ocean and a satellite in space and then send an "elevator" up it.
Excuse me... *COUGH*Bullshit*COUGH* Sorry...
I know, I know. I'm open minded enough to know that anything is possible but please, a 62,000 mile long piece of wire? Seems like the elevator would still face all the same problems as a conventional rocket, just having a wire to guide it wouldn't help it escape gravity. I'm not near smart enough to comment on this, I know that but I'm gonna take an "I'll believe it when I see it" stance on this one. Let's see, I'm almost 51 so I'll revisit this issue on my 66th birthday.
I know one other thing too, I sure wouldn't want to be around if that sucker broke...
posted by Big Ed at 11:08 AM
10 Comments:
Hi Ed.
I know, I know. I'm open minded enough to know that anything is possible but please, a 62,000 mile long piece of wire?
Not a wire but a meter wide by mm thin bit of CNT composite.
Seems like the elevator would still face all the same problems as a conventional rocket, just having a wire to guide it wouldn't help it escape gravity.
The wire doesn't guide the lifter. The lifter is clamped to the wire and ascends via mechancial means - rollers or wheels. Power is supplied externally by free electron laser.
I'm not near smart enough to comment on this, I know that but I'm gonna take an "I'll believe it when I see it" stance on this one. Let's see, I'm almost 51 so I'll revisit this issue on my 66th birthday.
You're smart enough to blog you're bright enough to grasp the basics. It's not that tough, really.
I know one other thing too, I sure wouldn't want to be around if that sucker broke...
You're thinking 'tower that falls'. The ribbon itself is (must be) feather light. What happens depends on where the break is. Some falls to earth, some breaks up on reentry, some goes whipping out into space.
See www.liftport.com - we have a FAQ and links to the NIAC documents (one is less than a hundred pages) that explain it in detail.
Did I make a mistake in the math somewhere or make a bad assumption somewhere?
I am honestly not sure. I'll bookmark this page and get check the assumptions.
Thanks for stopping by Brian. It's nice to see a new face (not that there's anything wrong with you old faces).
Not a wire but a meter wide by mm thin bit of CNT composite.
OK, a 62,000 mile long piece of meter wide by mm thin bit of CNT composite. It still stretches the imagination.
You're smart enough to blog you're bright enough to grasp the basics. It's not that tough, really.
Smart meaning that I just don't understand this technology. I'm not a scientist, I'm a technician. I work in the practical, not the theoretical. A 62,000 miles strand of anything really sets my bullshit filter off in a big way. Hell, a 100 mile strand would have me shaking my head.
You're thinking 'tower that falls'. The ribbon itself is (must be) feather light. What happens depends on where the break is. Some falls to earth, some breaks up on reentry, some goes whipping out into space.
No, I didn't figure it would fall over like a solid structure but if someone tied 10 billion feathers together, stretched it up into the air and turned it loose, I still wouldn't want to be under it when it came down. On the other hand, given the light weight of the thing, wouldn't the wind cause it to possibly spread out over a wide area and not just crumple down into a neat little pile. I don't know what the chances are of it breaking but putting the impact aside, fixing it if it did seems to be a pretty pricey deal.
I'll admit to anyone that I am severly lacking in the imagination department and that I'm too practical for my own good but there just seem like way too many hurdles to overcome to have something like this up and running in 15 years. Maybe in 50 years but 15, not a chance.
Brian, I went out and looked at your forums and there is some interesting stuff there, way too much for me to absorb in a short amount of time. Being a long time sci fi fan, I started coming up with some weird what ifs:
Given that it's not anchored but just extended out into space far enough to essentially not need an anchor, the end of that thing must be whipping thru space at an incredible speed.
Imagine if it hit something. Lots of junk flying around up there that could get in the way.
Imagine if it hit something that didn't break either the cable or what it hit. Take it a step further and imagine it wrapped around and anchored to whatever it hit.
Imagine if it broke and flung 200,000 Km of CNT out into space. Space is naturally a big place but should we be flinging tons of junk our there with no thought to what that might mean?
Let's go really sci fi, what if aliens grab it and use it to drag us off to Alpha Centauri or something??? OK, that last one was just for fun. Seriously, I don't worry about aliens hardly at all any more.
Now, let's get serious for a minute. I can certainly see why people would want more crap floating around in space but don't we have more pressing problems we need to solve right here. If you people can figure out how to make a cable that goes to the moon, couldn't you make us a cheap car that runs on water instead? How about curing the common cold or cancer or AIDS? It seems like a pipe drean to start off with but couldn't we work on a pipe dream that actually did something worthwhile for people? Space is great but seems like we could focus on a little more pressing problem than putting more crap over our heads.
You just know there would be some terrorists foaming at the mouth to blow that thing up.
How do you guard 62,000 miles of wire, I mean, CNT composite?
For some excellent simulations of what happens if it breaks, go here:
http://www.mit.edu/people/gassend/spaceelevator/breaks/index.html
I gotta tell ya, the one where it breaks at the counterweight and wraps around the earth had me ROFL.
The proposed final space elevator has a mass of 220 million pounds (100,000 tons) and can lift 5 tons a day. It would take 20,000 days (55 years) to double its orbital mass. If you start with a 20T elevator and and want to build a 100,000T elevator you will need to double the mass a little more than 12 times. That will take about 700 years.
Did I make a mistake in the math somewhere or make a bad assumption somewhere?
You've overestimated the weight of the cable, which happens. Before I dive in I will readily acknowledge that the material does not exist commercially, the stuff in the lab is not ready to be produced commercially, and not in the strength needed. LPG's position is that the terrestrial applications for material that meets our requirements is causing the CNT research labs to work hard on such and it should be ready sooner or later. We're betting on sooner.
Analogy is suspect but it's as if the guys building the Brooklyn Bridge needed to wait (as indeed they did) for the process to braid really long lengths of steel to be perfected. They could sit on their thumbs and wait or they could start raising money, designing the thing so it's all ready to go once the steel braiding guys work out the (pun) kinks.
In our case we're working on lifter tech, and trying to make inroads in the arenas where it counts - legal and political.
You'll pardon me if I stick to metric? You used imperial and metric and it muddled my button brain. I was told in school that we'd be using metric no later than 1979, casting aside the clunky imperial system and I believed them.
The proposed mass of the ribbon is 0.2 kilograms per km.
62,000 miles is 99,779 kilometers (km)
99779 * 0.2 = 19955.8 kilograms
(19955.8 kilograms is 43,995 pounds, 21 tons (Short US)
Smart meaning that I just don't understand this technology. I'm not a scientist, I'm a technician. I work in the practical, not the theoretical.
I've been doing IT in various capacities since 1989, when the Marines tried to teach me COBOL. I get the tech, but I had a head start (enthusiasm for space access) and I don't really understand the maths involved for CNT. I do savvy orbital mechanics on a high school level, which is all you really need.
I don't know what the chances are of it breaking but putting the impact aside, fixing it if it did seems to be a pretty pricey deal.
If it falls it's tear down time (so to speak). Working in our favor is that the first job for the very first SE will be to build a second. Now we've got a revenue ribbon and a ribbon making ribbon. What happens to the material from a fallen ribbon?
I see you found Blaise's animation for 'what happens' in a break. In the real world the majority of the ribbon is going to break up and the burn to ash on re-entry.
But yah, the 'wrapping around the world' bit is cute.
Imagine if it hit something that didn't break either the cable or what it hit. Take it a step further and imagine it wrapped around and anchored to whatever it hit.
Putting the anchor at sea allows us to move the ribbon to avoid traffic in orbit that has a regular pattern.
There are belts where debris is more common - for those areas the ribbon can be shaped to mitigate damage - say a small hole (which will be patched by a repair lifter). Stuff large enough to tear the ribbon in twain is indeed a problem.
If you people can figure out how to make a cable that goes to the moon, couldn't you make us a cheap car that runs on water instead? How about curing the common cold or cancer or AIDS
No doubt - but aren't there already people working on those problems? We're a rich enough society to afford people that build space ships AND work on an AIDS cure.
It seems like a pipe drean to start off with but couldn't we work on a pipe dream that actually did something worthwhile for people? Space is great but seems like we could focus on a little more pressing problem than putting more crap over our heads.
Cheap transportation always benefits the ends of the communication link, and increases wealth. Always. Why do we need cheap transport to space? 99% of the wealth in our solar system ain't here - it's elsewhere. Cheap access to space can solve our crisis problems - no exceptions.
You just know there would be some terrorists foaming at the mouth to blow that thing up.
How do you guard 62,000 miles of wire, I mean, CNT composite?
Some quick answers.
Devalue the target by making more space elevators. One is an invaluable resource. Many of them are merely an attractive target.
You don't need to guard the entire length. Right now the ability of terrs to attach beyond the first three miles is limited - they just can't get there from here. As well - the target is way the hell over the horizon - there won't BE anyone around to take pictures of the flaming wreckage. This is not an attractive ter target.
I have more questions and concerns but I'll take them over to the forums. Most of it is just me making noise except for this one.
No doubt - but aren't there already people working on those problems? We're a rich enough society to afford people that build space ships AND work on an AIDS cure.
Imagine if everyone who was working on a space elevator or working on a better tasting chocolate or working on mascara you could go swimming with all, for just one year or just one month or just one week all got together and worked toward finding a cure for AIDS. Imagine if all those computer cycles and all that money and all those brains got together and tried to figure out any of the real problems plaguing the modern world.
Do we have enought people working on a cure for AIDS? The answer is No. The reason is because people are still dying of AIDS.
I think that CNT composites (and other CNT technology) is great and all, and I certainly understand the business model of trying to weasel government grants. But I am still not seeing any numbers that make sense even to my extremely crude first order approximations.
I can't argue with your math - on the other hand I can't argue with the math that claims it all works either. With apologies I am numerate, perhaps, but not that numerate.
So I do what people must when you can't master every detail of a complex topic - you trust the people that do and listen to their opinions. This requiers a sophisticated BS detector of course.
I might be critcized for this approach but consider that a person who does not know the details of IC will take his care to an auto mechanic for work. You trust that the fellow who wrote your word processor didn't insert a trojan into the code.
I'm talked with some of the fellows involved with space elevators who do know enough to say yea or nay. I've read the source material, followed along as much as I could. My BS meter hasn't gone off yet, and I've had that on full gain.
Charles, I urge you to take your concerns to the LPG forum, as well as the Yahoo SE mail list. There are people there who can explain the numbers far better than I.
Imagine if all those computer cycles and all that money and all those brains got together and tried to figure out any of the real problems plaguing the modern world.
We're a rich society with a diversity of opinion. This is our strength. We have enough wealth (capital and human) to work on a broad spectrum of problems and ills.
You see AIDS as a problem. Fine. I see (among other items) that expensive access to space as a problem. Both problems can be worked on at the same time. And will be.
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