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The Space Elevator - Public or Private?
AtomicGoat writes "The Space Review reports that a Space Elevator may not get built without help from the U.S. Government, but the notion that 'the DoD can also provide a sense of fiscal discipline when dealing with large, expensive programs' sounds like an Onion story. Right now a small private company (Liftport), not NASA or the Air Force, is in the lead on revolutionary space travel."
No you can't, you can't stay in the Van Allen radiation belt for a long time, as it would be necessary in a space elevator. For more info have a look at Wikipedia - Van Allen radiation belt .
But the platform would be built on international waters, and the elevator will reach into space, which no government owns. I don't see why any government should have to get get involved, if the LiftPort Group can get this off the ground without any government help, all the more power to them!
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A space elevator would not so much be "put up" as "lowered down". The energy and materials requirements for lowering a cable from orbit are drastically different from building a tower to the stars.
When you lower a cable, it is relatively easy to anchor it to a floating platform in the middle of the ocean. Therefore, there is no worry about equatorial real estate, local population, eminent domain, or other government-dominated nonsense.
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Actually the cable seems quite safe even if part of it "falls". Please read the FAQ before such wild speculation.
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The "elevator" falling down is less dangerous than a sheet of newspaper falling down. It's that thin. It's not going to hurt anyone. They said it will likely break up and shred into small pieces as it falls. If it breaks anywhere within the atmosphere (due to weather, terrorism, plane crash, etc) only a few miles fall down and they simply lower some more down and reattach it. The few miles you lose in the atmosphere is a pittance.
It will be in international waters, off of South America (I want to say Peru?). So the buyoff of any government for land, airspace, etc is not required.
There are a LOT of hurdles left. Not only can the nanotube fibers not be made in sufficient length and quantity, but they have not even looked at what happens to a model of a few-meter wide ribbon in the atmosphere. We also don't have a lift vehicle capable of getting the big spool and counterweight they need up just past geosync orbit.
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A space elevator will be a cheap-to-operate lifter once it's in place, and it'll have the nice advantage of being able to take items FROM space as well.
This problem can be conquored with adequate shielding- and thus isn't really a problem.
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It looks like what I knew -- or thought I knew -- about space elevators is a bit dated. Which amounts to "wildly inaccurate" now. For those of you who might want to see some direct comparisons between the current technology and what was believed a few years ago, see LiftPort's Frequent Misconceptions page. It was enlightening, at least to me.
Oh for crissakes people, we're geeks supposedly, right?
geosynchronous orbit is at 22,300 miles. The reason that the cable needs to extend out past geosynchronous orbit is that the center of gravity has to be at 22,300 miles so the cable doesn't fall. That means making the cable the same length on both sides, tying off a large rock above 22,300 miles, or whatever. The point is that the cable has to have its center of gravity at 22,300 miles.
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Not sure I would be so quick to dismiss the DoD budgeting process or their fiscal responsibility. A few anectodal popular press examples of fiscal excess should not be taken as the rule. (It is actually debatable if the Gov't really did purchase $800 hammers etc, or "padded" the cost of these items to cover larger non-public expenses). So, the DoD method of Planning, Programming, and Budgeting is actually very robust and has a good deal of merit. The system is widely refered to as the PPBS. It has been around since the 1960's and was first introduced by then Secretary of Defense Robert McNamara. "The PPBS is a cyclic process containing three distinct but inter-related phases: planning, programming, and budgeting. The process provides for decisionmaking on future programs and permits prior decisions to be examined and analyzed from the viewpoint of the current environment (threat, political, economic, technological, and resources), and for the time period being addressed." There is both a 5-year and a 10-year horizon for this planning and budgeting. There is a connection between this process and the "big budget." And overruns, well that is another story. :)
For the really curious, here is the process. http://www.dtic.mil/whs/directives/corres/html/704 57.htm
...what a space elevator is, how it would work, and so forth, but really doesn't, check out this link. This is the NASA-sponsored report that basically declared it open season on space elevators. It's fascinating, in-depth, and answers questions such as "how do we build it" and "what happens when in falls/gets holes in it". A must-read for space buffs.
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If you can actually hit the elevator (which will be perhaps a few feet wide, not as easy to hit as a skyscraper) then all you will manage to do is snap off the very lowest portion of it, which is the easiest to fix.
First, I don't think you can just sew it back together. AFAIK there's no "fix" for a broken ribbon.
Second, if the ribbon is completely broken, the top will go flying into space. Its not just going to keep hanging there above the platform.
IOW if it breaks, you're back to square one (plus the experience).
Just to follow up from this, sounds like you're right. From http://liftport.com/research3.php
"Terrorists are unlikely to be able to break the elevator anywhere higher than 15 km or so; it can then be simply flown back down to the anchor by moving some of the counterweight mass a bit further out and will be back in operation in a couple of days."
Though they're not so much sewing it back together as they are trimming the end and re-anchoring. Good to know its so easy to fix.