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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."
but they do have a store. I want my liftport lunchbox! (http://www.cafepress.com/liftport.13005720)
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!
Sig? No thanks, I'm trying to quit.
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.
"This quote is a product of the Frobozz Magic Quote Company."
Actually the cable seems quite safe even if part of it "falls". Please read the FAQ before such wild speculation.
UNIX/Linux Consulting
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.
Real programmers use "copy con program.exe"
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.
SJW: a person who perceives an injustice, and while correcting it, commits a greater injustice.
that's geosynchronous orbit. The satellite at 62k miles is stationary with respect to a point on the ground below it. it just "hangs" there. Thats why you can lower a cable to that point from the satellite.
Otherwise, if it were shorter or longer, the cable would wrap around the earth, dragging the satellite down. Not a very effective elevator.
Moo.
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.
No weapon in the arsenals of the world is so formidable as the will and moral courage of free men.-Ronald Reagan
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
The space elevator was not created by science fiction writers. It was first theorized by Soviet scientist Yuri Artsutanov. Later there we some NASA papers that expanding on the theory. You can read about it here.
If you are going to debate the con side of this issue please produce facts not emotions.
UNIX/Linux Consulting
The proposed site isn't really just some spot in the middle of the ocean- it's some spot in the middle of the ocean, on the Equator. Not only does this make it possible to place a station on the cable at a geostationary orbit, but it confers the added bonus of being in a place where hurricanes are actually extremely rare- hurricanes, cyclones, and typhoons tend (but not always) to originate in belts called Intertropical Convergence Zones that flank the Equator, but do not stretch over it- in fact, the Equator lies in the band of low wind and calm seas aptly referred to as the doldrums.
"FDA staff reviewers expressed concern about the number of patients who were left out of the study because they died."
...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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1) it's not that long, and 2) if it breaks, only the part below the break falss; the part above flies off into space
If a job's not worth doing, it's not worth doing right.
Since a few of you are quoting a Wired article, let me remind you all of another article regarding the DOD's stated mission of "Dominating" the space arena and to deny other nations the ability to launch any platforms to space which we would deem to be contrary to our interests. See Wired magazine; "Peace is war" April 2002.
As you might recall from the article, Rumsfeld and others within the DOD have simply stated that space is too important to allow other nations to participate fully without our approval. Period. As an example, consider US lobbying and conditions in regards to the European GPS system.
from the article
Operation of a space elevator will not be allowed where it conflicts with our interests, this includes business interests too. Any venture providing access to space would most certainly have to have their payloads approved by the US government, even if the launching platform is 5000 miles out into the pacific somewhere.
Seems pretty clear, even if a private interest were to attempt to create a space elevator, they might find an un-invited "partner," regardless of their wishes. Soooo, might as well go with the flow and accept the DOD money right off the bat. No other way the project's gonna get done.
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).
Read their site. Theyr rely on centripital force to keep the cable taught, otherwise there would be no tension on the cable. They plan on putting the satellite outside of goesynchronus orbit.
http://www.liftport.com/research1.php
A geosynchronous orbit is any orbit with an orbital period that matches the sidereal day, which is 23 hours 56 minutes and 4 seconds in length, and represents the time taken for the Earth to rotate once about its polar axis relative to a distant fixed point.
A geostationary orbit is a special case of a geosynchronous orbit where a satellite appears stationary from the point of view of an observer on the Earth's surface. The conditions for geostationary orbits are:
- The orbit is geosynchronous
- The orbit is a circle
- The orbit lies in the plane of the Earth's equator
The terms are incorrectly used interchangeably...A couple of other handy facts:
Have you thought for yourself today?
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.
But the Earth will speed up on the return trip, so the net effect is no speed up/slow down at all.
Hooptie
"Heavens, it appears that my weewee has been stricken with rigor mortis!" -- Stewie Griffin
Because chemical rockets are a technological dead end for getting from Earth to orbit--they just aren't going to give much better performance in the future than they are today. How can we state this with any certainty? Two words: mass ratio. Fuel makes up most of the mass of any rocket at launch. Most of the rest goes on infrastructure -- engines, fuel tanks, guidance computers, etc, leaving a tiny percentage for passangers, payload etc. And there's no massive improvements left to be made in chemical rockets: we have the periodic table, we know we get the maximum theoretical bang by burning H and O, and it's just not enough to allow cheap access to space.
You could turn to nuclear power, but, generally speaking, nuclear propulsion inside the atmosphere is verboten.
So then you're left with either inventing totally new motive technology for rockets, or turning to something else, something that uses the gravity well to its advantage: something like the space elevator. Other contenders involve balloons and so on, but thess operate at the cusp of the atmosphere, or LEO at best -- a space elevator gets you all the way to geosynchronous orbit and way beyond.
"Just once, I'd like to meet an alien menace that wasn't immune to bullets." -- The Brigadier, Dr. Who
Just to correct that one trope: NASA has not lost the plans for the Saturn V -- although many paper copies were destroyed, a complete set of blueprints exists on microfilm in Marshall.
The real problem is that the plans for the assembly lines have probably all vanished: all the custom jigs and other tooling created and built up for the Apollo program. It's one thing to note on blueprint that, say, a Saturn F-1 engine outer housing needs to be sintered to the cooling pipe network in one go, but how on Earth do you actually do that?
"Just once, I'd like to meet an alien menace that wasn't immune to bullets." -- The Brigadier, Dr. Who
As early as 1895, a Russian scientist named Konstantin Tsiolkovsky suggested a fanciful "Celestial Castle" in geosynchronous Earth orbit attached to a tower on the ground, not unlike Paris's Eiffel tower. Another Russian, a Leningrad engineer by the name of Yuri Artsutanov, wrote some of the first modern ideas about space elevators in 1960. Published as a non-technical story in Pravda, his story never caught the attention of the West. Science magazine ran a short article in 1966 by John Isaacs, an American oceanographer, about a pair of whisker-thin wires extending to a geostationary satellite. The article ran basically unnoticed. The concept finally came to the attention of the space flight engineering community through a technical paper written in 1975 by Jerome Pearson of the Air Force Research Laboratory. This paper was the inspiration for Clarke's novel.
Why would anyone engrave "Elbereth"?
Since you had a good question, and no one has answered: I found this in the LiftPort FAQ:
Because of conservation of angular momentum, payloads going up the elevator will pull it down.
When an elevator ascends the ribbon, it must be accelerated eastward because the Earth's rotation represents a larger eastward velocity the higher you go. The required eastward force on the ascending elevator would have to be provided by a corresponding westward force on the ribbon, possibly requiring rockets at intervals along the cable.
If you go through the math quantitatively, the angular momentum for the climbers requires a few newtons of force over the one-week travel time, and we do that easily with our many tons of material in the anchor and the counterweight. The additional angular momentum will eventually be recovered from that of the entire Earth.
The quantities really are tiny, but just to be complete, a climber going up pushes the entire elevator slightly to the east, causing it to lean. However, the ribbon recovers for the same reason that it stays up in the first place. Centripetal acceleration is acting on the counterweight pulling it outward, and the lost angular momentum is replaced very quickly (essentially as fast as it is lost). The ribbon will never lose enough angular momentum to even deflect a single degree, let alone fall. The extra angular momentum is stolen from the Earth's rotation; we will have to worry about this effect slowing down the Earth and making the day longer if we ever decide to ship Australia into space.