Ken Burnside, about your space elevator.
- Thread starter Blue Ghost
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The literature for skyhooks has been around for decades. The issues being the cost to implement not resulting in a payoff in the expected 10-15 years of the skyhook, and the potential for catastrophic failures.
NASA and ESA are pathologically Risk Averse. Burt Rutan went to NASA with his "Shuttlecock" approach to reentry, and got told it was too risky to even work on. Then, he went to Paul Allen, and the rest is, literally, History. He's not fully proven it, but has sufficiently proven the concept that it now justifies further testing... and NASA is going to have to come to grips with regulation of a civil space program building in the US under FAA rules, flying under both FAA and NASA rules, and funded by private citizens putting wealthy folks in orbit.
The Space Ship 2 craft would be ideal for a 50-150 skyhook.... it gets up high enough that a skyhook wouldn't be deeply dragged.
It is important to realize tho' - NASA, ESA, and Roscosmos are NOT about best engineering practices. They're about National Prestige and National Security. (In the case of the ESA, joint European prestige, as the ESA is multinational.) Projects like skyhooks are within their science budgets, but lack prestige because they won't be useful without a place to go off world, and are too expensive for the current sat-launch demand. So they get plenty of "ivory Tower" time, but no budget for actually being implemented.
NASA and ESA are pathologically Risk Averse. Burt Rutan went to NASA with his "Shuttlecock" approach to reentry, and got told it was too risky to even work on. Then, he went to Paul Allen, and the rest is, literally, History. He's not fully proven it, but has sufficiently proven the concept that it now justifies further testing... and NASA is going to have to come to grips with regulation of a civil space program building in the US under FAA rules, flying under both FAA and NASA rules, and funded by private citizens putting wealthy folks in orbit.
The Space Ship 2 craft would be ideal for a 50-150 skyhook.... it gets up high enough that a skyhook wouldn't be deeply dragged.
It is important to realize tho' - NASA, ESA, and Roscosmos are NOT about best engineering practices. They're about National Prestige and National Security. (In the case of the ESA, joint European prestige, as the ESA is multinational.) Projects like skyhooks are within their science budgets, but lack prestige because they won't be useful without a place to go off world, and are too expensive for the current sat-launch demand. So they get plenty of "ivory Tower" time, but no budget for actually being implemented.
Well, I think the consensus here is that, even for a sci-fi setting, they're science-fiction.
Why on Earth (or anyplace else for that matter) you'd even consider building one as practical solution for getting stuff in space, to my way of thinking, is outside the realms of rational thought.
Another thought occurred to me, how do you keep your "beanstalk" (that name bugs the heck out of me) anchored to the ground? Assume you got a counterweight of the appropriate size and mass. How do you keep it from yanking up your Earth bound anchor? I'm assuming there's a concrete foundation where you'd start building the thing. I mean what's holding the foundation in place?
Foundations in construction stay put because of their mass pressing on the ground. But if you have something pulling the other way, then what keeps that structure stuck in the Earth?
Why on Earth (or anyplace else for that matter) you'd even consider building one as practical solution for getting stuff in space, to my way of thinking, is outside the realms of rational thought.
Another thought occurred to me, how do you keep your "beanstalk" (that name bugs the heck out of me) anchored to the ground? Assume you got a counterweight of the appropriate size and mass. How do you keep it from yanking up your Earth bound anchor? I'm assuming there's a concrete foundation where you'd start building the thing. I mean what's holding the foundation in place?
Foundations in construction stay put because of their mass pressing on the ground. But if you have something pulling the other way, then what keeps that structure stuck in the Earth?
Vladika
SOC-14 1K
Ground hooks and Hindu rope trick engineering. Yeah, I see a game here :rofl:
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You would do it if it was cheaper than the alternatives.
Either all studies have overlooked that problem or there is a theoretical engineering solution. Anchor the beanstalk to a mountain, perhaps.
Hans
Vladika
SOC-14 1K
And, here are the contenders. Not a beanstalk among them. (I guess nobody much believes in "magic" beans?)
Manned
(USA-NASA) Orion Multi-Purpose Crew Vehicle – capsule
(USA-SpaceX ) Dragon – capsule
(USA-Boeing) CST-100 – capsule
(USA-Sierra Nevada Corporation) Dream Chaser – suborbital spaceplane
(USA-The Spaceship Company) Spaceship Two – suborbital spaceplane
(USA-Blue Origin) New Shepard – VTVL capsule
(USA-XCOR) Lynx rocketplane – suborbital spaceplane
(Russia-RKA) Prospective Piloted Transport System (PPTS) – capsule
(China-CNSA) Shenzhou – capsule
(Europe-ESA) Advanced Crew Transportation System – capsule
(Iranian Space Agency) Orbital Vehicle – capsule
(India-ISRO) Orbital Vehicle – capsule
Unmanned
SpaceX Dragon – cargo delivery to the ISS
Orbital Sciences Cygnus – cargo delivery to the ISS
CNES Mars Netlander
James Webb Space Telescope (delayed)
ESA Darwin14 probe
Mars Science Laboratory rover
Shenzhou spacecraft Cargo
Terrestrial Planet Finder cancelled probe
System F6—a DARPA Fractionated Spacecraft demonstrator
Reaction Engines Limited Skylon (spacecraft)
Vladika
SOC-14 1K
I just played off your post Hans. It was just in the right place at the right time.
Michael
The total weekly launch capacity of even a small skyhook exceeds the annual world launch capacity. There isn't sufficient demand to make the skyhook superior to disposable rockets.
Certainly, if one were built, people WOULD find uses for it. But there isn't sufficient demand NOW to justify it. And we're talking putting a million tons into orbit to make it. That's 2billion pounds. At roughly $20,000 per pound. $40E12 just in launch costs. Plus the materials (post engineering, probably another $400 per pound.... or half a billion there). And, of course, the innumerable safety studies any of the governmental space agencies will use.
There's not enough economics in orbit to justify the smaller, faster, cheaper, easier, technically doable skyhook. Let alone the bigger, tougher, may-not-be-physically-doable beanstalk.
Skyhooks are, in a very real sense, "Doable Space Elevators". Keep the low point above 6 miles MSL, and you don't even have to worry about hitting the ground. Keep them above 24, and you have very little air - just enough to get a reusable plane up.
Certainly, if one were built, people WOULD find uses for it. But there isn't sufficient demand NOW to justify it. And we're talking putting a million tons into orbit to make it. That's 2billion pounds. At roughly $20,000 per pound. $40E12 just in launch costs. Plus the materials (post engineering, probably another $400 per pound.... or half a billion there). And, of course, the innumerable safety studies any of the governmental space agencies will use.
There's not enough economics in orbit to justify the smaller, faster, cheaper, easier, technically doable skyhook. Let alone the bigger, tougher, may-not-be-physically-doable beanstalk.
Skyhooks are, in a very real sense, "Doable Space Elevators". Keep the low point above 6 miles MSL, and you don't even have to worry about hitting the ground. Keep them above 24, and you have very little air - just enough to get a reusable plane up.
... and like the beanstalk, most of the contenders will never exist.
(but because of Economics, not Physics).
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