Re:Link to online version of the book manuscript
on
The Space Elevator
·
· Score: 1
That's not the book manuscript; it's the original report to NASA, finished quite some time before the book. The book is much longer, has quite a bit more analysis, and introduces some new ideas that may lower the initial costs substantially.
The HighLift site (www.highliftsystems.com) also has an active forum (under "Interact" in the nav bar) that has discussed all of the issues being raised by/.ers in these comments. There's also a pretty good FAQ.
Let's say the anchor asteroid gets disconnected at the top end. The elevator will fall down and wrap itself around the whole of Earth's equator!
The current plans don't involve an asteroid; you've probably read Green Mars. The space elevator that will almost certainly be feasible in the next two decades will be approximately the width of a sheet of paper, and much thinner.
Can you imagine the consequences
If it is somehow severed at GEO, the point of highest tension (and some 22,000 miles from Earth, hard for terrorists to get to), only the lowest fraction will enter the atmosphere slowly enough so as not to burn up. Possibly as much as 3000 kg of cable will make it down to the surface, spread over 500-1000 km. The "consequences" will border on the undetectable.
If the Space Elevator is severed in the atmosphere or Low Earth Orbit, where terrorists could get to it with airplanes or missles, lightning could strike, etc, not much will happen; the remainder will just move into a slightly higher orbit over a period of days. Just move the counterweight a bit farther out or unreel a bit more cable and the cut end will float down to the surface and can be re-attached. For that reason, the elevator won't be much of a target for terrorists; no huge, spectacular effect like buildings falling or hundreds of people dying.
"fast"? Um, to construct, or in use? Because a space elevator will take a long, long time to construct, and payload on an elevator actually would take several days to come up or down.
Current estimate is two years after construction starts. Payloads take a week to get to GEO, but start up at four-day intervals. That's 12,000 kg to geosynchronous orbit every four days, a thousand tons a year. Compare to current launch rates.
"cheap"? ROFL. It would be by far the largest and most expensive engineering project ever undertaken. The biggest project, period. Trillions and trillions of dollars over many years.
Current estimate: $15 billion. Bill Gates could do it himself from his checking account.
"can be created with technology avaible [sic] in the next two to there [sic] years"? We don't even know if it's possible with current materials science.
Yes, we do. Tests show that carbon nanotubes should be able to reach strengths in the 150-200 GPa range. We don't need quite that much. Actual working cables in the 10 GPa range have been created.
There's a huge and somewhat surprising amount of ignorance about space elevators on slashdot. Some, but not all, of it is due to the way they have been portrayed in science fiction. The massive, million-ton constructs of Red Mars and The Fountains of Paradise just aren't the way things are really going to happen.
The future arrives sooner than you expect, and in a different order.
These books were written before carbon nanotubes were discovered. They all postulated that space elevators would have to be many meters thick and weigh billions of tons. In fact, the SE proposed by Brad Edwards of HighLift would start out just ten cm wide and one micron thick. If it breaks, it would flutter down.
Seem to be quite a few replies from people who learn their science from science fiction.
I was involved with the huge effort Xerox made to convert technologies that PARC invented (Ethernet, Alto) and claims to have invented (laser printer, mouse, GUI) into a commercially-viable office information system. It was like pulling teeth to get anything out of those guys and, when you did, it turned out to be a complete hack job, quick-and-very-dirty code that could do no more than stagger through a carefully-controlled demo.
It makes me crazy to see PARC continue to claim things that were invented by others. There was a working prototype of the laser printer long before PARC was founded, and Doug Englebart had invented the mouse and GUI well before the last fruit crop was harvested from their future site.
PARC did a great many good things, and Xerox failed miserably to take advantage of them, but the standard story that PARC promulgates hugely exaggerates the facts.
We visited Doug in early 1968 or late 1967, then went back to Brown and continued to work on Hypertext for the IBM/360, completely inspired by him. Years later I was agast (and still am) at what Xerox PARC claimed to have invented. I guess that BT is just picking up the tradition.
It seems to me that the basic chord keyboard idea is due to be re-invented for use with things like PDAs and cellphones that are too small to have a QWERTY keyboard.
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That's not the book manuscript; it's the original report to NASA, finished quite some time before the book. The book is much longer, has quite a bit more analysis, and introduces some new ideas that may lower the initial costs substantially.
/.ers in these comments. There's also a pretty good FAQ.
The HighLift site (www.highliftsystems.com) also has an active forum (under "Interact" in the nav bar) that has discussed all of the issues being raised by
The current plans don't involve an asteroid; you've probably read Green Mars. The space elevator that will almost certainly be feasible in the next two decades will be approximately the width of a sheet of paper, and much thinner.
Can you imagine the consequences
If it is somehow severed at GEO, the point of highest tension (and some 22,000 miles from Earth, hard for terrorists to get to), only the lowest fraction will enter the atmosphere slowly enough so as not to burn up. Possibly as much as 3000 kg of cable will make it down to the surface, spread over 500-1000 km. The "consequences" will border on the undetectable.
If the Space Elevator is severed in the atmosphere or Low Earth Orbit, where terrorists could get to it with airplanes or missles, lightning could strike, etc, not much will happen; the remainder will just move into a slightly higher orbit over a period of days. Just move the counterweight a bit farther out or unreel a bit more cable and the cut end will float down to the surface and can be re-attached. For that reason, the elevator won't be much of a target for terrorists; no huge, spectacular effect like buildings falling or hundreds of people dying.
Current estimate is two years after construction starts. Payloads take a week to get to GEO, but start up at four-day intervals. That's 12,000 kg to geosynchronous orbit every four days, a thousand tons a year. Compare to current launch rates.
"cheap"? ROFL. It would be by far the largest and most expensive engineering project ever undertaken. The biggest project, period. Trillions and trillions of dollars over many years.
Current estimate: $15 billion. Bill Gates could do it himself from his checking account.
"can be created with technology avaible [sic] in the next two to there [sic] years"? We don't even know if it's possible with current materials science.
Yes, we do. Tests show that carbon nanotubes should be able to reach strengths in the 150-200 GPa range. We don't need quite that much. Actual working cables in the 10 GPa range have been created.
There's a huge and somewhat surprising amount of ignorance about space elevators on slashdot. Some, but not all, of it is due to the way they have been portrayed in science fiction. The massive, million-ton constructs of Red Mars and The Fountains of Paradise just aren't the way things are really going to happen.
The future arrives sooner than you expect, and in a different order.
Seem to be quite a few replies from people who learn their science from science fiction.
It makes me crazy to see PARC continue to claim things that were invented by others. There was a working prototype of the laser printer long before PARC was founded, and Doug Englebart had invented the mouse and GUI well before the last fruit crop was harvested from their future site.
PARC did a great many good things, and Xerox failed miserably to take advantage of them, but the standard story that PARC promulgates hugely exaggerates the facts.
It seems to me that the basic chord keyboard idea is due to be re-invented for use with things like PDAs and cellphones that are too small to have a QWERTY keyboard.