Talk:Space elevator/Archive 5

message: Should we have a "space elevator humor" section in the article ?
* http://www.schlockmercenary.com/d/20010123.html
* http://www.miami.com/images/miami/miamiherald/7227/52236682730.jpg
- I wouldn't have thought so, it doesn't seem very encyclopedia-like Wolfkeeper 00:35, 6 Apr 2005 (UTC)
replies: text: Well, that's what talk pages are for! Eh? Right. So, anyway, a rabbi walks into a space elevator with a poodle under one arm and a big feather in his other hand... Beanluc 00:28, 26 October 2005 (UTC)
thread_title:  space elevator humor 

message: 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)
replies: text: You're right, that section greatly overstates the effects (as well as using dubiously scary statements to suggest the effects can't even be predicted). Space elevator#In the event of failure already discusses what sort of impact a break in the elevator would have, so I'm going to trim those bits out of the sabotage section. If someone wishes to dispute it then that's where the text should be disputed. Bryan 01:00, 14 Apr 2005 (UTC)

text: The falling cable would have a limited (even if high) speed at falling, so there would be time for early warning of affected areas.--Deelkar  (talk) 19:35, 30 Apr 2005 (UTC)
thread_title:  impact of falling cable? 

message: 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)
: We could move it to a new article called "Space Elevator Physics" -- Klafubra 13:09, 17 May 2005 (UTC)
thread_title: Cable Taper Calculations, necessary?

message: 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)
thread_title: Organizations

message: 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)
thread_title:  Spoken Article 

message: 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
:That might be better placed over at Space elevator economics. siafu 02:27, 17 August 2005 (UTC)
thread_title:  Economics of Space Elevator 

message: 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.
:This is speculation and original research.  Definitely needs to be cut. siafu 17:12, 13 September 2005 (UTC)
thread_title:  Obsession with the US Military? 

message: 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.
:This pointed out further up on this page. Its easy to show that this must be the case. Infact the CG needs to be quite a long way from Geo. In the case of using a tether as the counterweight, much of the cable would be way past the geo and the dynamics arn't as good. So for the most part there will always be a counterweight. Probably a space station of some sort.
:I am going to edit this page to fix the CG issue and replace the graphic. But it won't be untill the weekend.--Delt0r 07:52, 18 October 2005 (UTC)
replies: text: "Center of mass" and "center of gravity" (CG) mean very different things in this case, be cautious. The center of gravity only needs to be a little way out beyond geosynchronous, and in fact could theoretically be right at geosynchronous if it weren't for the need to lift payloads and provide safety margins. Bryan 08:05, 18 October 2005 (UTC)
replies: text: Ah, I see the problem now - the diagram uses "center of mass" when it should be using "center of gravity". Changing just that word should fix it. Bryan 08:07, 18 October 2005 (UTC)
replies: text: Good point. I missed the mixing up of these terms. I think making a clear distinction between these terms may be needed. Most engineers use both terms as equivalent.--Delt0r 08:47, 18 October 2005 (UTC)
replies: text: Yeah, I've noticed that the center of mass article makes that mistake quite a bit itself. Hopefully to be fixed within the next few days. :) Bryan 00:00, 19 October 2005 (UTC)
thread_title:  Geosynchronous orbit 

message: 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?
:I think the ways in which a lunar elevator are easier than an Earth-based one are sufficiently numerous and extreme that we can say it's more than just an opinion and it shouldn't be removed. We don't need to go into great detail in this article about it, since we've got a separate article specifically on the subject that we can refer readers to. Bryan 00:51, 2 November 2005 (UTC)
replies: text: Now just think about this.  If two bodies are tidally locked (the situation where one side of a body always facing the one its orbitting), there is obviously a sycnhronous orbit facing directly away from the larger body as well, not to mention that the L1 Langrangian point would also qualify. siafu 22:24, 11 January 2006 (UTC)
thread_title:  See Also - Lunar Space Elevator 

message: 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)
replies: text: "the limit to which a material can be stretched without irreversibly deforming" is a poor definition of tensile strength.  First of all, "stretch" is a reference to strain, not stress which is the common unit of strength.  Secondly, that's a definition of the elastic limit, which is a different concept from yield or ultimate strength.  Carbon nanotubes are nearly linear-elastic to failure, which means that the elastic limit and the ultimate strength are quite close, and the concept of yield is not really applicable.  Typically for non-ductile materials the ultimate strength is considered to be the limit state, so the usefull definition of tensile strength in this article is the stress (load per unit area) a material can be subjected to without breaking. Toiyabe 23:46, 15 February 2006 (UTC)
thread_title:  Tensile Strength 

message: 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
#The article doesn't open with a clear opening explanation of what a space elevator is... the concept, in plain English
#Space fountains aren't that plausible.
#Compressive structures aren't defined or linked.
Plowboylifestyle 06:15, 22 November 2005 (UTC)
thread_title:  Gripes with this article. 

message: 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)
replies: text: Plouwboylifestyle, you asked on my personal page which images from the Liftport gallery were okay to use to update the Space Elevator entry - use any images you want.  We're open about re-using those images as long as attribution is made to Liftport Group and they are not re-used for commercial purposes Bdunbar 12:35, 2 January 2006 (UTC)
thread_title:  Graphics