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lTAPER CALCULATION WRONG
i believe the taper calculation between earth and geo is wrong. it is exp [p/s * (4.8*10^7]] this agrees with the taper calculation on Pearsons paper
The atmosphere is part of the Earth. Earth surface is about 100 to 120 km atop the sea level !!! While living INSIDE the Earth at the interface between the atmosphere and the lithosphere, we very well know how to climb through the atmosphere and reach a fixed point with helicopters and baloons, no need for 100km towers. Gas baloons can easily get up to 40 km in the stratosphere and serve as shuttles for delivery/recovery of payloads to the base of the elevator. 40 km higher base implies very significant reduction in cable masse and width alowing for lower strenghth requierements. sorry for my english and thanks for your time :)
I agree that, especially in the political issues section, a lot of time is wasted exposing rather obvious issues like 'we will have to decide who gets to use it and when?' I think everyone knows that already. Furthermore, there is definite leftist POV about togetherness and international cooperation and sustainable technology and other buzz words with far reaching implications. Those implications include the shutting out of the private sector, the use of hard-earned money of citizens who might not want to fund such a venture, the lack of respect for state sovereignty, and the ability of a public venture to needlessly politicize what could potentially be a peaceful, free-market venture. I'mm not saying this debate should take place on this page, perhaps just remove that section or clean it up to make it encyclopedic. Lumano 05:19, 24 October 2005 (UTC)
Hmm... looking over the talk page, I can see this is a somewhat controversial article, so quite frankly, I'd rather not get involved, but an anon just added some content that reads like someone's personal POV essay rather than like encyclopedic information, ie: unqualified statements about government motivations, etc.: http://en.wikipedia.org/w/wiki.phtml?title=Space_elevator&curid=29192&diff=0&oldid=0 func (talk) 21:04, 27 Nov 2004 (UTC)
On the basis of the above, I've changed the wording from "...and it is becoming ever more obvious that space is a significant military resource" to "...and it is becoming ever more obvious that space is likely to be militarised". I think the use of the phrase "military resource" quietly condones the use of space as a result, wherease the simple statement of likelyhood is more verifiable. Hughcharlesparker 23:19, August 18, 2005 (UTC)
- I have added a couple of novels. Also there was a mistake where it said "to minimize the weight in the middle" that should be "to minimize the maximum stress that experienced at any point per unit area". -Gunjan
- Fredrik | talk 09:46, 15 Dec 2004 (UTC)
Interesting, by the way: apparently my structural edit got broken into three (check the page history). There must have been some issues with the database, as saving did take a while and I got an error message while previewing. The end result seems correct though. Fredrik | talk 09:50, 15 Dec 2004 (UTC)
I have added one diagram. Did I get the details right? Fredrik | talk 12:31, 15 Dec 2004 (UTC)
What about some simple calculations, and best guess numbers, as to journey time, likely weight limits, that sort of thing. The average reader, like me would like to know what this thing would most likely be capable off and what it wouldn't be capable off. Ian —The preceding unsigned comment was added by 162.61.65.5 ( talk • contribs) .
Wolfkeeper moved some comments about NIAC from the article body into references. While this may be a good decision, I am not fully comfortable with the article's current position towards Bradley. While I intend in no way to question his qualifications, he is currently called "a leading authority on the space elevator concept", which may not be the most accurate statement. Bolonkin gives a detailed description of corruption in NIAC [1] and also strongly criticises the report by Edwards and Cassanova, saying that "The 42-page report [which costed taxpayers almost 1 million dollars], half of which is mere illustrations, represents a mere explanation of the idea of the space elevator intended for elementary school pupils." [2]. I think that this information should be reflected in the article in some form, and our praise for Edwards should be somewhat limited. Paranoid 18:25, 17 Jan 2005 (UTC)
The center of mass of the space elevator must be higher than the geosynchronous orbit, to exploit Earth's angular momentum when the climber goes up. If its center of mass is exactly at the geosynchronous orbit, it becomes unstable as soon as the climber goes up because of Coriolis force.
The space elevator involves something that ideally orbits over the same point on the ground. This implies no elevator over the poles. Unless the orbit matches the earth's rotation, the tether will swish over the whole planet.----
___|___ / | \ / | \______ | | | \---------------O counterweight | | | | | | \ | / \___|___/ | axis
(Sorry for the poor figure.) The space elevator is stable if it circulates Earth geosynchronously at an orbit where the three forces of centrifugal force, the cable tension, and Earth's gravity cancel. The latter two forces don't have to be perpendicular to the axis, as far as their combined force is perpendicular. This orbit is away from the equatorial plane. - TAKASUGI Shinji 06:56, 9 Mar 2005 (UTC)
Is the "center of mass" really the critical feature? I agree in that it must lie "higher" than geosynchronical orbit, but this results automatically since the crucial concept seems to be the fact that the *sum* of centrifugal force and earth's gravity is zero in any point of the cable. Or am I wrong with this notion?
Hochnebel 14:08, 11 Mar 2005 (UTC+1)
if I've understood you correctly... the whole cable is *necessarily* under slightly more tension than the theoretical minimum necessary, so the sums don't quite cancel. And that's because the center of mass is above geo. And if it wasn't, then elevator would lean slightly, pushing the CofM below GEO and then it would actually fall right down to the ground.
O counterweight | | | | Climber O→ Coriolis force (goes up)| | ---------+----------- East ← West Earth
O counterweight |↓(dragged down by tension) | | | Climber O→ Coriolis force (goes up) / / ---------+----------- East ← West Earth
Conservation of momentum. Initially the elevator has no load and is assumed to be vertical, but a low-momentum load is being raised. The total momentum will be reduced at the end of the process and the elevator will not return to vertical.
If the line is always taut, which is not advisable since this implies the earth is pulling the whole contraption around and around, and if the line breaks the whole thing will just fly off.
But there is no pendulum because everything is falling.
A load plucks the line and causes a wave, but when everything settles down due to heat loss, everything will have sagged. Conservation of energy, i.e., no free lunch, means something needs to be done regularly to lift the whole system back to its original place. ----
One possible design I thought when I read the article was to use The Quantum theory on how to move the elevator. If you could separate the Elevator's quantas, as quantas come as pairs, to leave one of the two quantas in the elevator, and the other one in the destination; then, by attaching the destination's quantas and making them to not move, you then would make those quantas to "move up" or to move them in the opposit direction than the elevator, so then the elevaotr's quantas will move, making the elvator travel. It's just a thought maybe you could check it.201.155.99.44 04:32, 22 April 2006 (UTC)ANDRES VALENCIA, MEXICO CITY, 2006201.155.99.44 04:32, 22 April 2006 (UTC
Should we have a "space elevator humor" section in the article ?
- I wouldn't have thought so, it doesn't seem very encyclopedia-like
Wolfkeeper 00:35, 6 Apr 2005 (UTC)
Section 3.5 reads "the devastation created by thousands of tons of cable striking across hundreds of miles at terminal velocity could have unimaginable effects". Posts on slashdot.org, however, suggest that there might be very little devastation. To quote from this post:
The surviving fragments of an orbital tether would not have the requisite mass to produce the sort of wave disturbances you postulate. Actually, from most accounts, the worst health hazard resulting from a broken orbital tether would be small fragments of nanotube floating about in the atmosphere, eventually drifting to ground level and getting lodged in the lungs (as it turns out, carbon nanotubes are about the same size as asbestos fibers...perfect for getting lodged in the lungs).
Also, to quote from this post:
That's why you don't build it as a cable. You build it as a ribbon, with lots of surface area. If the ribbon snaps, portions high up in the atmosphere will burn up upon reentry. The portions of the cable that don't burn will flutter to the ground - think tickertape parades.
I don't know enough about the issue to make any comments, myself, but the above seems to suggest that a bit more justificiation as to why (or why not) a falling cable would have a devastating impact. TerraFrost 19:59, 13 Apr 2005 (UTC)
The "Meteoroids and micrometeorites" section of the article describes how minor damage would be expected to cause cascading fiber breakage and destruction of the cable. Has this been addressed in the literature, and is there a proposed solution to the problem?
Well, Freeman Dyson's view on the problem is that space elevators will not work because of this problem: "but I am willing to be persuaded wrong". If a man who showed mathematically that it might be possible to use nuclear bombs as a propulsion device to launch from the surface of the Earth thinks it looks tough, IMO it may be a difficult problem to solve. WolfKeeper 00:47, 2005 May 3 (UTC)
Interesting. Can you supply a citation for this?
An edit and its motivation: In the summary, the sentence
has been changed and expanded to:
The change to the first sentence tightens it up and then notes the existence of potential solutions to a wide range of problems. The added sentence notes what is, to the best of my knowledge, a unique issue in that it is potentially fatal and as yet unaddressed, with no proposed solution. I believe that this issue is important to evaluating the space elevator proposal, and should be highlighted in part to stimulate efforts to address it. Note that Wolfkeeper (above) found that Freeman Dyson sees this as a critical issue.
I am sure that this change will be unpopular because it highlights a serious problem in a popular idea. Potential criticisms might be:
Perhaps a shield of some sort could be constructed after the space elevator becomes load bearing for cargo. Something shaped like an open, windblown umbrella, with the handle being a small diameter shield around the cable ?? meters, and the larger lower section designed to deflect debris coming in from a higher orbit at an angle. These shields would probably have to have manuevering systems built in to move with the tether, which would add a refueling cost to the tether, plus increased maintenance to ensure the tether shield would be reliable. We could use the multilayer shielding ideas that have been used for the space station, with improvements of course. Just a thought...
The Stub Maker - Zotel
I moved this material back from Van Allen Radiation Belt (it was moved from here to there, but really is too spcific for that article). However, there is already a section on radiation hazards in the article. So I'm leaving this here. RJFJR 02:45, May 11, 2005 (UTC)
When the Apollo astronauts travelled to the moon the astronauts received about 1% of a lethal dose in the few hours they were crossing these regions of space. By way of contrast a space elevator will spend anywhere from hours to weeks in these regions, and if the final destination is geosynchronous orbit, the length of stay could be indefinite. Without shielding, this could pose a serious risk to passengers.
As with nuclear power, the problem is that the necessary radiation shielding is very heavy - much heavier than the people it protects; having to lift the passengers as well as the shielding may increase the ticket price many times over the equivalent quantity of freight (since most freight wouldn't be affected by radiation issues and doesn't require shielding).
The radiation belts are based on Earth's magnetic field, which is tilted at about 11 degrees from its rotational axis. They are further distorted by the solar wind, giving them a teardrop shape. Due to this, the elevator will encounter varying intensities of radiation; especially concerning is the inner belt.
One proposal for two way elevator systems to deal with the outer belt is to have extra shielding "in-place" along the cable that is carried up by a climbing elevator, and carried back down by a descending elevator to meet the next elevator carrying passengers up. While this adds constant weight to the elevator (as if a "permanent payload"), it adds the weight to the elevator where the cable is thickest and most able to tolerate extra payload. The "weak point" of the elevator is where it meets the Earth, and shielding is not needed there.
Another type of shielding is so-called "active" shielding. One such type involves electromagnetic fields to deflect low-energy radiation. Another type of active shielding is the Multilayer High Temperature Superconductor Protection System, which involves using high-temperature superconducting materials to produce strong magnetic fields for deflection. [3]. In theory, anything that produces a strong magnetic field could be used to deflect the radiation, but the strength of the magnetic field produced given the weight of the materials required can be a limiting factor. Active shielding, in its current designs, is very effective at shielding from protons of energies up to 200MeV, but is largely ineffective against galactic cosmic radiation (GCR) [4]. As the dangerous inner Van Allen belt consists mostly of protons from energies between 10 and 100 MeV, and particles in the outer van allen belts are lower energy (around 1 MeV) [ [5]], active shielding is a realistic option for the transit up to GEO. However, since it is ineffective against GCR, long-term human stays at GEO would require physical shielding in the structure they are to stay at.
There is also a proposal by the late Bob Forward called HiVolt which may be a way to drain at least parts of the Van Allen belts to 1% of their natural level within a year.
Mechanical climbers on the space elevator could draw energy from the belts as they travel through it. This would provide some power to the climber, and, after several thousand climbs, the belts would be reduced to a tiny fraction of their original intensity.
This article is causing a length warning. Looking through it the Cable Taper section looks expendable. I considered moving it to its own page, but I didn't think it would have enough context to make sense. Or we could just delete the whole thing, but I like the 4 points at the end. Anyone have a good idea about this section? RJFJR 02:45, May 11, 2005 (UTC)
Could a space elevator be an energy source by using the thermal/electrical differential between Earth's surface and cold space/the ionosphere? Ultramarine 19:54, 12 May 2005 (UTC)
user:Wolfkeeper moved most of the article to Beanstalk, which was previously a redirect here. I changed both back. I didn't care if he moved all the article there, I objected to moving part of the article.
I am of the opinion we should pick one name and have the other redirect to it. I don't care which is which I just don't want part of the text at one and part at the other. They look like synonyms to me so have one article.
(That is different than the proposal to have a seperate article on the physics of the space elevator, which would result in a more focused article and one that meets the length recommendation. I like that idea.) RJFJR 15:56, May 20, 2005 (UTC)
(If it gets moved then the talk page should go with it. RJFJR 16:02, May 20, 2005 (UTC))
I think Wikipedia must be descriptive of terminology use, not prescriptive. I haven't done a rigorous survey, but it seems to me that when most people these days talk about beanstalks, they use the term "space elevator" to describe it - all ten of the top Google results for "space elevator" are focused on the cable kind (though one's Wikipedia itself so that doesn't really count :). Furthermore, "space elevator" gets 2.3 million hits on Google compared to only half a million for "beanstalk", so I think we should probably go with that. Bryan 23:36, 20 May 2005 (UTC)
To keep it up to FA level, please remove external links from text, move to references and link back to relevant sections with Wikipedia:Footnotes. -- Piotr Konieczny aka Prokonsul Piotrus Talk 9 July 2005 18:10 (UTC)
I wish to start the practice of showing when the External link was last updated and by whom. On fast changing technology it is a pain to re-visit a web site that has not changed since visited last. If we can keep update dates noted in this section then it may encourage the External site to stay current and updated. I have taken the liberty to do this to an Organization link here. What do others think? (and to note if the link to the site is broken)
Space elevator, Institute for Scientific Research - added -> "Last news item dated July of 2004." -- Bobwinmill 16:06, 13 September 2005 (UTC)
I would personally love to read this and make it into a spoken article, but I'm completely unfamiliar with the process and would require some guidance from a more experienced wikipedian...(although I've been told I have a good voice and would love to use it for the betterment of mankind)...if anyone is interested in assisting me in this endeavor, please contact me...my aim sn is liberty484 and my email is antiantitrust at mail.com. Paul 05:21, 27 July 2005 (UTC)
A recent IEEE Spectrum Article had a good article on space elevators.
The main advantage of space elevators would be a large drop in the cost of sending a payloads into orbit. Currently it costs $20,000 (USD) to send a single kilogram into orbit. According to the article, after the first space is elevator is built the cost would drop to only $200 per kilogram. After multiple space elevators are constructed the article predicted the cost could drop as low as $10 per kilogram. In other words a successful space elevator would greatly reduce the cost of getting objects into orbit.
Here's the link for people who want to add to the wikipedia article:
http://www.spectrum.ieee.org/WEBONLY/publicfeature/aug05/0805spac.html
Though this could be true:
"The U.S. military may covertly oppose a space elevator. By granting inexpensive access to space, a space elevator permits less-wealthy opponents of the U.S. to gain military access to space—or to challenge U.S. control of space. An important U.S. military doctrine is to maintain space and air superiority during a conflict. In the current political climate, concerns over terrorism and homeland security could be possible grounds for more overt opposition to such a project by the U.S. government."
Its clearly speculation, and every military in the world have reasons to covertly oppose a space elevator. We could re-write this paragraph to cover the Chinese, Russian, and Indian Militaries, and the Israeli military might very well go bonkers at the thought of their enemies gaining the ability to bombard them from space with material brought up with inexpensive lift capability. In fact a space elevator complicates national defense for everyone, but so does the internet, international trade, and the widespread availability of common household cleansers and cell phones which are now used to make bombs and detonators.
I hesitate to dive in and delete some one else’s work, but it seems to me that there should either be a section speculating about who might oppose the project. This could include just about everyone on earth because who knows what anyone –may- do? Or this one paragraph should be dropped.
As mentioned before (but for other reasons) the centre-of-mass of tether isn't at geosynchronous orbit. This is because kepler's laws apply for point masses. Treating extended objects as point masses is only realistic when the gravitational field is uniform.
Also, the tether doesn't really need a counterweight as depicted in the graphic. The tether IS the counterweight.
Hi. Arthur C. Clarke has mentioned the discovery of a new material in a [ at Times Online]. Someone with a good background in the subject could consider updating it with this inforation. The text goes as "This situation has now changed, with the discovery of the third form of carbon, C60, and its relatives, the Buckminsterfullerenes. If these can be mass-produced, building a space elevator would be a completely viable engineering proposition." - Yves Junqueira, 2/oct/2005.
Yes, the Buckminsterfullerenes that are potentially useful for SEs are also known as carbon nanotubes. The article already discusses these. WolfKeeper
Recently we have gained the ability to industrialy mass-produce carbon nanotubes. I have read that the cost of construction would be around $10.000.000.000. Why hasn't this new information been included in this page?
Contains the line "Lunar space elevator for the (far) more easily built moon variant" Does this denote opinion and if so can or should it be removed? I would argue that both lunar and terrestrial space elevators are in the paper phase and it is difficult to say with precision which is easier to build.
Granted, on paper a lunar SE does not have the rigid design contrainst a terrestrial one will, but 'easy' is not just the design but financing, legal issues engineering experience and so on. Thoughts?
>>>Isn't the moon's geo(luna?)synchronous orbit at the Earth's center, since the same face of the moon always faces Earth? Jan. 11, 2006
Hi. I noticed that the Space elevator article describes "tensile strength" as being "the limit to which a material can be stretched without irreversibly deforming" but the Tensile strength article states that:
"The tensile strength of a material is the maximum amount of tensile stress that it can be subjected to before it breaks."
Upon further reading of the tensile strength article, it looks like tensile strength is divided into "yield" and "ultimate" (the former being the limit of tensile stress which material can endure and retain its elasticity, and the latter being the limit of tensile stress before the material breaks).
Does anybody think that the elevator article should be updated to clarify this issue, and what is the best way to do so? Cheers TigerShark 10:25, 12 November 2005 (UTC)
The opening section of the article should just focus on what space elevator does, how it works, and stick with the most plausible structure, the tether lowered from orbit held up by centrifugal force. I'd like to rewrite the first couple of paragraphs and move the discussion of space fountains to a later section, or someone else can, here is my list of gripes
Plowboylifestyle 06:15, 22 November 2005 (UTC)
I know this has been discussed at length. But face it, the space elevator concept is the geosynchronous orbital tether. Plowboylifestyle 20:16, 26 November 2005 (UTC)
The word beanstalk is nice, it should be mentioned, but it should be replaced by the word tether. Otherwise please proove that beanstalk is in common use. Other names and elevator concepts should be mentioned but not prominent. Plowboylifestyle 20:16, 26 November 2005 (UTC)
If I, or a few people I might converse with, were to call a person an idiot, a fool, or use even more generally harsh and insulting terms, or conversely laud someone, sincerely or sarcastically, calling them a "genius", a "hero", or even "the god", then in those contexts I might argue that such a person's name was synonymous to those words for me, or a few others, but that hardly makes any such word or name a synonym in any absolute or general sense.To say something can be synonymous does not carry quite the same connotations as the flat statement that a word is synonymous with another, which implies to many people that the words are primarily synonyms, and not merely incidentally so, in specific contexts, within specific groups.
The statement which was added, and which I objected to, flatly states : "The term 'space elevator' is usually synonymous with beanstalk", and I state flatly that this is usually NOT the case. I have therefore substituted this: "Space elevators have also sometimes been referred to as space bridges, beanstalks or space ladders."
This is closer to the statement previously there: "A space elevator is also referred to as a space bridge or star ladder" but I have dropped the term "star ladder" which I found to have about 800 google hits but primarily in the context of a "ladder towards stardom", or some sort of graphic design; there were only about 119 when "star ladder" & "space elevator" were both included, and even for less ambiguous terms there were only about 155 for a joint search of "space ladder" & "space elevator" and only about 747 for "space bridge" & "space elevator". There were only 635 for a joint search of both "beanstalk" & "space elevator". ~ Achilles † 14:31, 27 November 2005 (UTC)
Achilles † 23:22, 28 November 2005 (UTC) : I am restoring the cohesion of my previous statement by removing four interjections into it which occurred, and placing them below. I believe that it goes against standard Wikipedia etiquette to break up a person's statements in this way, and to someone coming upon the page it could even seem like I had been the rude one, not signing sporadic comments that no longer cohere well. Please stop this practice, as it is extremely annoying. Make your arguments in a coherent way, rather than snipping apart cohesive statements with your sniping.
The interjections that I removed from my statement were as follows — as some ask either rhetorical or sarcastic questions of me I will respond to them, immediately after the question:
1) First, there was a simple comment on the word "beanstalk":
2) The statement which was added, and which I objected to, flatly states : "The term 'space elevator' is usually synonymous with beanstalk", and I state flatly that this is usually NOT the case.
3) I have therefore substituted this: "Space elevators have also sometimes been referred to as space bridges, beanstalks or space ladders."
4) I have dropped the term "star ladder" which I found to have about 800 google hits but primarily in the context of a "ladder towards stardom", or some sort of graphic design; there were only about 119 when "star ladder" & "space elevator" were both included, and even for less ambiguous terms there were only about 155 for a joint search of "space ladder" & "space elevator" and only about 747 for "space bridge" & "space elevator".
To this I can only respond that a few hundred occurrences on the entire Web is hardly an overwhelming endorsement of the widespread or prevalent use of the term. ~ Achilles † 23:22, 28 November 2005 (UTC)
I also wish to make clear that I never argued that beanstalk had to be removed entirely, merely that I agreed with others that it was overused at the point this discussion began. That is no longer the case at this point in time. ~ Achilles † 23:31, 28 November 2005 (UTC)
I guess part of the reason I'm down on emphasizing space fountains and compressive structures so early in the article is because they are very much the subjects of fiction, plausable yes, feasable probably not. Where as orbital tethers are the subject of numerous active research projects and one commercial venture, they could very possibly become as real as the space shuttles in our lifetime. I think there needs to be some way of pointing this out early. Plowboylifestyle 21:32, 27 November 2005 (UTC)
Generally speaking I avoid making direct edits to this article, wanting to avoid even the appearance of a conflict of interest. However, some of the graphic images - used with our after-the-fact permission - could stand to be updated. I can do this readily enough by substituting an updated image for ones in place - or would it be better to let a wiki user not affiliated with Liftport do this? See www.liftport.com/gallery for imagery. brian dunbar 14:17, 28 November 2005 (CDT)
Brian, I'm not sure why its a conflict of interest. If one of the other space elevator companies wants to use there images on the page, they are welcome too right? ;) Just remmember NPOV and I think your fine. Plowboylifestyle 21:17, 29 November 2005 (UTC)
Yeah, it would seem kind of odd if there was a problem with people submitting material to Wikipedia that they explicitly have the right to submit, requiring other third parties to step in and submit it instead. If worst comes to worst the old image can be reverted to, just like with old revisions of article text. Out-of-date images might still be useful for illustrating historical concepts. Bryan 06:41, 30 November 2005 (UTC)
I've just finished reading Clarke's Sunstorm, and in it, as in many of his other books, he mentions the beginnings of a space elevator. However, this one is situated near Perth, and Clarke makes the point of stating that, contrary to earlier beliefs, such an elevator need not be based at the equator. Now in one of his earlier works of fiction, he went so far as to rename and relocate his beloved Sri Lanka onto the equator, so that it could be the base of such a structure.
My question is, how could a space elevator be built other than on the equator? If one was built, say, at Perth, would it pull perpendicular to the tangent of the earth at that point (thus defining a sort of truncated cone), or would it be perpendicular to the earth's axis? I mean, at the equator, these two are one and the same. But how would it be at a higher latitude? And why has thinking changed on this? I scanned the article and seemed to find confirmation that the space elevator does not need to be at the equator, but I still have my questions.
I am, by the way, without any significant scientific education, so feel free to talk down to me. Unschool 00:48, 26 December 2005 (UTC)
A question regarding language and writing for this intelligent, creative (capable even of creating new physics) responsive forum: What is a generic term for the object a satellite orbits? In other words finish this sentence: A satellite orbits an ----. Do not say heavenly body! Therealhrw 19:30, 28 December 2005 (UTC)
![]() | This page is an archive of past discussions. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page. |
lTAPER CALCULATION WRONG
i believe the taper calculation between earth and geo is wrong. it is exp [p/s * (4.8*10^7]] this agrees with the taper calculation on Pearsons paper
The atmosphere is part of the Earth. Earth surface is about 100 to 120 km atop the sea level !!! While living INSIDE the Earth at the interface between the atmosphere and the lithosphere, we very well know how to climb through the atmosphere and reach a fixed point with helicopters and baloons, no need for 100km towers. Gas baloons can easily get up to 40 km in the stratosphere and serve as shuttles for delivery/recovery of payloads to the base of the elevator. 40 km higher base implies very significant reduction in cable masse and width alowing for lower strenghth requierements. sorry for my english and thanks for your time :)
I agree that, especially in the political issues section, a lot of time is wasted exposing rather obvious issues like 'we will have to decide who gets to use it and when?' I think everyone knows that already. Furthermore, there is definite leftist POV about togetherness and international cooperation and sustainable technology and other buzz words with far reaching implications. Those implications include the shutting out of the private sector, the use of hard-earned money of citizens who might not want to fund such a venture, the lack of respect for state sovereignty, and the ability of a public venture to needlessly politicize what could potentially be a peaceful, free-market venture. I'mm not saying this debate should take place on this page, perhaps just remove that section or clean it up to make it encyclopedic. Lumano 05:19, 24 October 2005 (UTC)
Hmm... looking over the talk page, I can see this is a somewhat controversial article, so quite frankly, I'd rather not get involved, but an anon just added some content that reads like someone's personal POV essay rather than like encyclopedic information, ie: unqualified statements about government motivations, etc.: http://en.wikipedia.org/w/wiki.phtml?title=Space_elevator&curid=29192&diff=0&oldid=0 func (talk) 21:04, 27 Nov 2004 (UTC)
On the basis of the above, I've changed the wording from "...and it is becoming ever more obvious that space is a significant military resource" to "...and it is becoming ever more obvious that space is likely to be militarised". I think the use of the phrase "military resource" quietly condones the use of space as a result, wherease the simple statement of likelyhood is more verifiable. Hughcharlesparker 23:19, August 18, 2005 (UTC)
- I have added a couple of novels. Also there was a mistake where it said "to minimize the weight in the middle" that should be "to minimize the maximum stress that experienced at any point per unit area". -Gunjan
- Fredrik | talk 09:46, 15 Dec 2004 (UTC)
Interesting, by the way: apparently my structural edit got broken into three (check the page history). There must have been some issues with the database, as saving did take a while and I got an error message while previewing. The end result seems correct though. Fredrik | talk 09:50, 15 Dec 2004 (UTC)
I have added one diagram. Did I get the details right? Fredrik | talk 12:31, 15 Dec 2004 (UTC)
What about some simple calculations, and best guess numbers, as to journey time, likely weight limits, that sort of thing. The average reader, like me would like to know what this thing would most likely be capable off and what it wouldn't be capable off. Ian —The preceding unsigned comment was added by 162.61.65.5 ( talk • contribs) .
Wolfkeeper moved some comments about NIAC from the article body into references. While this may be a good decision, I am not fully comfortable with the article's current position towards Bradley. While I intend in no way to question his qualifications, he is currently called "a leading authority on the space elevator concept", which may not be the most accurate statement. Bolonkin gives a detailed description of corruption in NIAC [1] and also strongly criticises the report by Edwards and Cassanova, saying that "The 42-page report [which costed taxpayers almost 1 million dollars], half of which is mere illustrations, represents a mere explanation of the idea of the space elevator intended for elementary school pupils." [2]. I think that this information should be reflected in the article in some form, and our praise for Edwards should be somewhat limited. Paranoid 18:25, 17 Jan 2005 (UTC)
The center of mass of the space elevator must be higher than the geosynchronous orbit, to exploit Earth's angular momentum when the climber goes up. If its center of mass is exactly at the geosynchronous orbit, it becomes unstable as soon as the climber goes up because of Coriolis force.
The space elevator involves something that ideally orbits over the same point on the ground. This implies no elevator over the poles. Unless the orbit matches the earth's rotation, the tether will swish over the whole planet.----
___|___ / | \ / | \______ | | | \---------------O counterweight | | | | | | \ | / \___|___/ | axis
(Sorry for the poor figure.) The space elevator is stable if it circulates Earth geosynchronously at an orbit where the three forces of centrifugal force, the cable tension, and Earth's gravity cancel. The latter two forces don't have to be perpendicular to the axis, as far as their combined force is perpendicular. This orbit is away from the equatorial plane. - TAKASUGI Shinji 06:56, 9 Mar 2005 (UTC)
Is the "center of mass" really the critical feature? I agree in that it must lie "higher" than geosynchronical orbit, but this results automatically since the crucial concept seems to be the fact that the *sum* of centrifugal force and earth's gravity is zero in any point of the cable. Or am I wrong with this notion?
Hochnebel 14:08, 11 Mar 2005 (UTC+1)
if I've understood you correctly... the whole cable is *necessarily* under slightly more tension than the theoretical minimum necessary, so the sums don't quite cancel. And that's because the center of mass is above geo. And if it wasn't, then elevator would lean slightly, pushing the CofM below GEO and then it would actually fall right down to the ground.
O counterweight | | | | Climber O→ Coriolis force (goes up)| | ---------+----------- East ← West Earth
O counterweight |↓(dragged down by tension) | | | Climber O→ Coriolis force (goes up) / / ---------+----------- East ← West Earth
Conservation of momentum. Initially the elevator has no load and is assumed to be vertical, but a low-momentum load is being raised. The total momentum will be reduced at the end of the process and the elevator will not return to vertical.
If the line is always taut, which is not advisable since this implies the earth is pulling the whole contraption around and around, and if the line breaks the whole thing will just fly off.
But there is no pendulum because everything is falling.
A load plucks the line and causes a wave, but when everything settles down due to heat loss, everything will have sagged. Conservation of energy, i.e., no free lunch, means something needs to be done regularly to lift the whole system back to its original place. ----
One possible design I thought when I read the article was to use The Quantum theory on how to move the elevator. If you could separate the Elevator's quantas, as quantas come as pairs, to leave one of the two quantas in the elevator, and the other one in the destination; then, by attaching the destination's quantas and making them to not move, you then would make those quantas to "move up" or to move them in the opposit direction than the elevator, so then the elevaotr's quantas will move, making the elvator travel. It's just a thought maybe you could check it.201.155.99.44 04:32, 22 April 2006 (UTC)ANDRES VALENCIA, MEXICO CITY, 2006201.155.99.44 04:32, 22 April 2006 (UTC
Should we have a "space elevator humor" section in the article ?
- I wouldn't have thought so, it doesn't seem very encyclopedia-like
Wolfkeeper 00:35, 6 Apr 2005 (UTC)
Section 3.5 reads "the devastation created by thousands of tons of cable striking across hundreds of miles at terminal velocity could have unimaginable effects". Posts on slashdot.org, however, suggest that there might be very little devastation. To quote from this post:
The surviving fragments of an orbital tether would not have the requisite mass to produce the sort of wave disturbances you postulate. Actually, from most accounts, the worst health hazard resulting from a broken orbital tether would be small fragments of nanotube floating about in the atmosphere, eventually drifting to ground level and getting lodged in the lungs (as it turns out, carbon nanotubes are about the same size as asbestos fibers...perfect for getting lodged in the lungs).
Also, to quote from this post:
That's why you don't build it as a cable. You build it as a ribbon, with lots of surface area. If the ribbon snaps, portions high up in the atmosphere will burn up upon reentry. The portions of the cable that don't burn will flutter to the ground - think tickertape parades.
I don't know enough about the issue to make any comments, myself, but the above seems to suggest that a bit more justificiation as to why (or why not) a falling cable would have a devastating impact. TerraFrost 19:59, 13 Apr 2005 (UTC)
The "Meteoroids and micrometeorites" section of the article describes how minor damage would be expected to cause cascading fiber breakage and destruction of the cable. Has this been addressed in the literature, and is there a proposed solution to the problem?
Well, Freeman Dyson's view on the problem is that space elevators will not work because of this problem: "but I am willing to be persuaded wrong". If a man who showed mathematically that it might be possible to use nuclear bombs as a propulsion device to launch from the surface of the Earth thinks it looks tough, IMO it may be a difficult problem to solve. WolfKeeper 00:47, 2005 May 3 (UTC)
Interesting. Can you supply a citation for this?
An edit and its motivation: In the summary, the sentence
has been changed and expanded to:
The change to the first sentence tightens it up and then notes the existence of potential solutions to a wide range of problems. The added sentence notes what is, to the best of my knowledge, a unique issue in that it is potentially fatal and as yet unaddressed, with no proposed solution. I believe that this issue is important to evaluating the space elevator proposal, and should be highlighted in part to stimulate efforts to address it. Note that Wolfkeeper (above) found that Freeman Dyson sees this as a critical issue.
I am sure that this change will be unpopular because it highlights a serious problem in a popular idea. Potential criticisms might be:
Perhaps a shield of some sort could be constructed after the space elevator becomes load bearing for cargo. Something shaped like an open, windblown umbrella, with the handle being a small diameter shield around the cable ?? meters, and the larger lower section designed to deflect debris coming in from a higher orbit at an angle. These shields would probably have to have manuevering systems built in to move with the tether, which would add a refueling cost to the tether, plus increased maintenance to ensure the tether shield would be reliable. We could use the multilayer shielding ideas that have been used for the space station, with improvements of course. Just a thought...
The Stub Maker - Zotel
I moved this material back from Van Allen Radiation Belt (it was moved from here to there, but really is too spcific for that article). However, there is already a section on radiation hazards in the article. So I'm leaving this here. RJFJR 02:45, May 11, 2005 (UTC)
When the Apollo astronauts travelled to the moon the astronauts received about 1% of a lethal dose in the few hours they were crossing these regions of space. By way of contrast a space elevator will spend anywhere from hours to weeks in these regions, and if the final destination is geosynchronous orbit, the length of stay could be indefinite. Without shielding, this could pose a serious risk to passengers.
As with nuclear power, the problem is that the necessary radiation shielding is very heavy - much heavier than the people it protects; having to lift the passengers as well as the shielding may increase the ticket price many times over the equivalent quantity of freight (since most freight wouldn't be affected by radiation issues and doesn't require shielding).
The radiation belts are based on Earth's magnetic field, which is tilted at about 11 degrees from its rotational axis. They are further distorted by the solar wind, giving them a teardrop shape. Due to this, the elevator will encounter varying intensities of radiation; especially concerning is the inner belt.
One proposal for two way elevator systems to deal with the outer belt is to have extra shielding "in-place" along the cable that is carried up by a climbing elevator, and carried back down by a descending elevator to meet the next elevator carrying passengers up. While this adds constant weight to the elevator (as if a "permanent payload"), it adds the weight to the elevator where the cable is thickest and most able to tolerate extra payload. The "weak point" of the elevator is where it meets the Earth, and shielding is not needed there.
Another type of shielding is so-called "active" shielding. One such type involves electromagnetic fields to deflect low-energy radiation. Another type of active shielding is the Multilayer High Temperature Superconductor Protection System, which involves using high-temperature superconducting materials to produce strong magnetic fields for deflection. [3]. In theory, anything that produces a strong magnetic field could be used to deflect the radiation, but the strength of the magnetic field produced given the weight of the materials required can be a limiting factor. Active shielding, in its current designs, is very effective at shielding from protons of energies up to 200MeV, but is largely ineffective against galactic cosmic radiation (GCR) [4]. As the dangerous inner Van Allen belt consists mostly of protons from energies between 10 and 100 MeV, and particles in the outer van allen belts are lower energy (around 1 MeV) [ [5]], active shielding is a realistic option for the transit up to GEO. However, since it is ineffective against GCR, long-term human stays at GEO would require physical shielding in the structure they are to stay at.
There is also a proposal by the late Bob Forward called HiVolt which may be a way to drain at least parts of the Van Allen belts to 1% of their natural level within a year.
Mechanical climbers on the space elevator could draw energy from the belts as they travel through it. This would provide some power to the climber, and, after several thousand climbs, the belts would be reduced to a tiny fraction of their original intensity.
This article is causing a length warning. Looking through it the Cable Taper section looks expendable. I considered moving it to its own page, but I didn't think it would have enough context to make sense. Or we could just delete the whole thing, but I like the 4 points at the end. Anyone have a good idea about this section? RJFJR 02:45, May 11, 2005 (UTC)
Could a space elevator be an energy source by using the thermal/electrical differential between Earth's surface and cold space/the ionosphere? Ultramarine 19:54, 12 May 2005 (UTC)
user:Wolfkeeper moved most of the article to Beanstalk, which was previously a redirect here. I changed both back. I didn't care if he moved all the article there, I objected to moving part of the article.
I am of the opinion we should pick one name and have the other redirect to it. I don't care which is which I just don't want part of the text at one and part at the other. They look like synonyms to me so have one article.
(That is different than the proposal to have a seperate article on the physics of the space elevator, which would result in a more focused article and one that meets the length recommendation. I like that idea.) RJFJR 15:56, May 20, 2005 (UTC)
(If it gets moved then the talk page should go with it. RJFJR 16:02, May 20, 2005 (UTC))
I think Wikipedia must be descriptive of terminology use, not prescriptive. I haven't done a rigorous survey, but it seems to me that when most people these days talk about beanstalks, they use the term "space elevator" to describe it - all ten of the top Google results for "space elevator" are focused on the cable kind (though one's Wikipedia itself so that doesn't really count :). Furthermore, "space elevator" gets 2.3 million hits on Google compared to only half a million for "beanstalk", so I think we should probably go with that. Bryan 23:36, 20 May 2005 (UTC)
To keep it up to FA level, please remove external links from text, move to references and link back to relevant sections with Wikipedia:Footnotes. -- Piotr Konieczny aka Prokonsul Piotrus Talk 9 July 2005 18:10 (UTC)
I wish to start the practice of showing when the External link was last updated and by whom. On fast changing technology it is a pain to re-visit a web site that has not changed since visited last. If we can keep update dates noted in this section then it may encourage the External site to stay current and updated. I have taken the liberty to do this to an Organization link here. What do others think? (and to note if the link to the site is broken)
Space elevator, Institute for Scientific Research - added -> "Last news item dated July of 2004." -- Bobwinmill 16:06, 13 September 2005 (UTC)
I would personally love to read this and make it into a spoken article, but I'm completely unfamiliar with the process and would require some guidance from a more experienced wikipedian...(although I've been told I have a good voice and would love to use it for the betterment of mankind)...if anyone is interested in assisting me in this endeavor, please contact me...my aim sn is liberty484 and my email is antiantitrust at mail.com. Paul 05:21, 27 July 2005 (UTC)
A recent IEEE Spectrum Article had a good article on space elevators.
The main advantage of space elevators would be a large drop in the cost of sending a payloads into orbit. Currently it costs $20,000 (USD) to send a single kilogram into orbit. According to the article, after the first space is elevator is built the cost would drop to only $200 per kilogram. After multiple space elevators are constructed the article predicted the cost could drop as low as $10 per kilogram. In other words a successful space elevator would greatly reduce the cost of getting objects into orbit.
Here's the link for people who want to add to the wikipedia article:
http://www.spectrum.ieee.org/WEBONLY/publicfeature/aug05/0805spac.html
Though this could be true:
"The U.S. military may covertly oppose a space elevator. By granting inexpensive access to space, a space elevator permits less-wealthy opponents of the U.S. to gain military access to space—or to challenge U.S. control of space. An important U.S. military doctrine is to maintain space and air superiority during a conflict. In the current political climate, concerns over terrorism and homeland security could be possible grounds for more overt opposition to such a project by the U.S. government."
Its clearly speculation, and every military in the world have reasons to covertly oppose a space elevator. We could re-write this paragraph to cover the Chinese, Russian, and Indian Militaries, and the Israeli military might very well go bonkers at the thought of their enemies gaining the ability to bombard them from space with material brought up with inexpensive lift capability. In fact a space elevator complicates national defense for everyone, but so does the internet, international trade, and the widespread availability of common household cleansers and cell phones which are now used to make bombs and detonators.
I hesitate to dive in and delete some one else’s work, but it seems to me that there should either be a section speculating about who might oppose the project. This could include just about everyone on earth because who knows what anyone –may- do? Or this one paragraph should be dropped.
As mentioned before (but for other reasons) the centre-of-mass of tether isn't at geosynchronous orbit. This is because kepler's laws apply for point masses. Treating extended objects as point masses is only realistic when the gravitational field is uniform.
Also, the tether doesn't really need a counterweight as depicted in the graphic. The tether IS the counterweight.
Hi. Arthur C. Clarke has mentioned the discovery of a new material in a [ at Times Online]. Someone with a good background in the subject could consider updating it with this inforation. The text goes as "This situation has now changed, with the discovery of the third form of carbon, C60, and its relatives, the Buckminsterfullerenes. If these can be mass-produced, building a space elevator would be a completely viable engineering proposition." - Yves Junqueira, 2/oct/2005.
Yes, the Buckminsterfullerenes that are potentially useful for SEs are also known as carbon nanotubes. The article already discusses these. WolfKeeper
Recently we have gained the ability to industrialy mass-produce carbon nanotubes. I have read that the cost of construction would be around $10.000.000.000. Why hasn't this new information been included in this page?
Contains the line "Lunar space elevator for the (far) more easily built moon variant" Does this denote opinion and if so can or should it be removed? I would argue that both lunar and terrestrial space elevators are in the paper phase and it is difficult to say with precision which is easier to build.
Granted, on paper a lunar SE does not have the rigid design contrainst a terrestrial one will, but 'easy' is not just the design but financing, legal issues engineering experience and so on. Thoughts?
>>>Isn't the moon's geo(luna?)synchronous orbit at the Earth's center, since the same face of the moon always faces Earth? Jan. 11, 2006
Hi. I noticed that the Space elevator article describes "tensile strength" as being "the limit to which a material can be stretched without irreversibly deforming" but the Tensile strength article states that:
"The tensile strength of a material is the maximum amount of tensile stress that it can be subjected to before it breaks."
Upon further reading of the tensile strength article, it looks like tensile strength is divided into "yield" and "ultimate" (the former being the limit of tensile stress which material can endure and retain its elasticity, and the latter being the limit of tensile stress before the material breaks).
Does anybody think that the elevator article should be updated to clarify this issue, and what is the best way to do so? Cheers TigerShark 10:25, 12 November 2005 (UTC)
The opening section of the article should just focus on what space elevator does, how it works, and stick with the most plausible structure, the tether lowered from orbit held up by centrifugal force. I'd like to rewrite the first couple of paragraphs and move the discussion of space fountains to a later section, or someone else can, here is my list of gripes
Plowboylifestyle 06:15, 22 November 2005 (UTC)
I know this has been discussed at length. But face it, the space elevator concept is the geosynchronous orbital tether. Plowboylifestyle 20:16, 26 November 2005 (UTC)
The word beanstalk is nice, it should be mentioned, but it should be replaced by the word tether. Otherwise please proove that beanstalk is in common use. Other names and elevator concepts should be mentioned but not prominent. Plowboylifestyle 20:16, 26 November 2005 (UTC)
If I, or a few people I might converse with, were to call a person an idiot, a fool, or use even more generally harsh and insulting terms, or conversely laud someone, sincerely or sarcastically, calling them a "genius", a "hero", or even "the god", then in those contexts I might argue that such a person's name was synonymous to those words for me, or a few others, but that hardly makes any such word or name a synonym in any absolute or general sense.To say something can be synonymous does not carry quite the same connotations as the flat statement that a word is synonymous with another, which implies to many people that the words are primarily synonyms, and not merely incidentally so, in specific contexts, within specific groups.
The statement which was added, and which I objected to, flatly states : "The term 'space elevator' is usually synonymous with beanstalk", and I state flatly that this is usually NOT the case. I have therefore substituted this: "Space elevators have also sometimes been referred to as space bridges, beanstalks or space ladders."
This is closer to the statement previously there: "A space elevator is also referred to as a space bridge or star ladder" but I have dropped the term "star ladder" which I found to have about 800 google hits but primarily in the context of a "ladder towards stardom", or some sort of graphic design; there were only about 119 when "star ladder" & "space elevator" were both included, and even for less ambiguous terms there were only about 155 for a joint search of "space ladder" & "space elevator" and only about 747 for "space bridge" & "space elevator". There were only 635 for a joint search of both "beanstalk" & "space elevator". ~ Achilles † 14:31, 27 November 2005 (UTC)
Achilles † 23:22, 28 November 2005 (UTC) : I am restoring the cohesion of my previous statement by removing four interjections into it which occurred, and placing them below. I believe that it goes against standard Wikipedia etiquette to break up a person's statements in this way, and to someone coming upon the page it could even seem like I had been the rude one, not signing sporadic comments that no longer cohere well. Please stop this practice, as it is extremely annoying. Make your arguments in a coherent way, rather than snipping apart cohesive statements with your sniping.
The interjections that I removed from my statement were as follows — as some ask either rhetorical or sarcastic questions of me I will respond to them, immediately after the question:
1) First, there was a simple comment on the word "beanstalk":
2) The statement which was added, and which I objected to, flatly states : "The term 'space elevator' is usually synonymous with beanstalk", and I state flatly that this is usually NOT the case.
3) I have therefore substituted this: "Space elevators have also sometimes been referred to as space bridges, beanstalks or space ladders."
4) I have dropped the term "star ladder" which I found to have about 800 google hits but primarily in the context of a "ladder towards stardom", or some sort of graphic design; there were only about 119 when "star ladder" & "space elevator" were both included, and even for less ambiguous terms there were only about 155 for a joint search of "space ladder" & "space elevator" and only about 747 for "space bridge" & "space elevator".
To this I can only respond that a few hundred occurrences on the entire Web is hardly an overwhelming endorsement of the widespread or prevalent use of the term. ~ Achilles † 23:22, 28 November 2005 (UTC)
I also wish to make clear that I never argued that beanstalk had to be removed entirely, merely that I agreed with others that it was overused at the point this discussion began. That is no longer the case at this point in time. ~ Achilles † 23:31, 28 November 2005 (UTC)
I guess part of the reason I'm down on emphasizing space fountains and compressive structures so early in the article is because they are very much the subjects of fiction, plausable yes, feasable probably not. Where as orbital tethers are the subject of numerous active research projects and one commercial venture, they could very possibly become as real as the space shuttles in our lifetime. I think there needs to be some way of pointing this out early. Plowboylifestyle 21:32, 27 November 2005 (UTC)
Generally speaking I avoid making direct edits to this article, wanting to avoid even the appearance of a conflict of interest. However, some of the graphic images - used with our after-the-fact permission - could stand to be updated. I can do this readily enough by substituting an updated image for ones in place - or would it be better to let a wiki user not affiliated with Liftport do this? See www.liftport.com/gallery for imagery. brian dunbar 14:17, 28 November 2005 (CDT)
Brian, I'm not sure why its a conflict of interest. If one of the other space elevator companies wants to use there images on the page, they are welcome too right? ;) Just remmember NPOV and I think your fine. Plowboylifestyle 21:17, 29 November 2005 (UTC)
Yeah, it would seem kind of odd if there was a problem with people submitting material to Wikipedia that they explicitly have the right to submit, requiring other third parties to step in and submit it instead. If worst comes to worst the old image can be reverted to, just like with old revisions of article text. Out-of-date images might still be useful for illustrating historical concepts. Bryan 06:41, 30 November 2005 (UTC)
I've just finished reading Clarke's Sunstorm, and in it, as in many of his other books, he mentions the beginnings of a space elevator. However, this one is situated near Perth, and Clarke makes the point of stating that, contrary to earlier beliefs, such an elevator need not be based at the equator. Now in one of his earlier works of fiction, he went so far as to rename and relocate his beloved Sri Lanka onto the equator, so that it could be the base of such a structure.
My question is, how could a space elevator be built other than on the equator? If one was built, say, at Perth, would it pull perpendicular to the tangent of the earth at that point (thus defining a sort of truncated cone), or would it be perpendicular to the earth's axis? I mean, at the equator, these two are one and the same. But how would it be at a higher latitude? And why has thinking changed on this? I scanned the article and seemed to find confirmation that the space elevator does not need to be at the equator, but I still have my questions.
I am, by the way, without any significant scientific education, so feel free to talk down to me. Unschool 00:48, 26 December 2005 (UTC)
A question regarding language and writing for this intelligent, creative (capable even of creating new physics) responsive forum: What is a generic term for the object a satellite orbits? In other words finish this sentence: A satellite orbits an ----. Do not say heavenly body! Therealhrw 19:30, 28 December 2005 (UTC)