If you haven't seen it already, here is the paper Blaise Gassend gave at the 2004 space elevator conference regarding non-equatorial SEs:
http://web.mit.edu/gassend/www/publications/NonEquatorialUniformStressSpaceElevators.pdf
and the corresponding ppt presentation:
http://web.mit.edu/gassend/www/spaceelevator/3rd-conference-notes/OffEquator-Talk.pdf

[edit]There are links to these in one of the links at the top of this thread too. I just now saw that  :wink: .

I'm sorry, I don't quite follow. I get the part about having twin ribbons that are each 100,000km in length. What does the 4,939km length of ribbon do?

Can we calculate the minimum launch time interval for an oscillating SE? For starters, the Edwards elevator requires that the first climber reach 19400km in altitude (the 0.1G point) before the second climber is launched. Will this be the same for an oscillating SE or are there other limitations?

I have heard that number as well - 7.1 hours is the characteristic frequency of the ribbon (due to the moon’s and sun’s gravities I’m guessing?) Is this a coincidence? Granted, Dr. Edwards has not had time you have had to go over the details of oscillation so he may be wrong on this point.

Andreas,

It occurred to me after reading Dr. Edwards reply that he was thinking of a different oscillation scenario. I wrote to him again to ask specifically about vertical oscillations. He said that tangling would be an issue. Friction would be an issue as well, he said, but might be alleviated by separating the bottom ends of the ribbons after launch. I will include part of his reply.

I contacted Dr. Edwards about his paper. He said he was unaware of any publications addressing oscillating SEs, but pointed out that due to the low mass per length of ribbon it would be difficult to provide the energy needed. Compounding the matter, the energy would need to be provided without causing high stress on the ribbon.

Excerpt from the Space Elevator Development Program by Bradley Edwards (55th International Astronautical Congress 2004)
http://www.spaceelevator.com/docs/iac-2004/iac-04-iaa.3.8.2.01.edwards.pdf

As promising as this sounds, I have not seen any papers on oscillating SE.

Doesn't A/cm represent current capacity? Oohms is of greater importance when talking about superconductivity.

He should check out PongSat. http://www.jpaerospace.com/pongsat/index.htm.

JP Areospace lets students and schools fly small experiments into space at no cost.

Because it's romantic. Seriously though, you're right Bob. With telepresence and an SE in place, manned missions to LEO will be unneeded, more costly and dangerous. I think the objection was that telepresence destroys our fiction space pilot fantasies.


This thread has strayed from it's original topic. I believe the disagreement was between those who don't trust corporations to regulate themselves and those who don't trust governments to regulate corporations. However it works out, I would prefer to have the corporation that is intimate with the operations of SEs to have their say in any regulations put forward. Liftport is registered in the US, so it's income will be taxed by the US. The government can monitor Liftport’s behavior, but I don't think the use of facilities in international waters will be regulated by anyone other than Liftport.

The 1.454% is the increase in ribbon mass, but it is not the increase in capacity. Because taper has to increase according to the square law, most of your new mass will be very close to GEO. The capacity will not go up as much as you suggest. What do you think the cross-section ratio is between earth and 1/2 GEO? Assuming a 1.5 taper, I don't think it is quite 1.25.

New Jersey perhaps? http://www.eurekalert.org/pub_releases/2006-08/njio-nrs080306.php

This is true for the first climber, but I'm looking at the result after 71 climbers or 207 climbers. Your method just adds material in such a way that the rate of capacity increase decreases. You also make it impossible. Consider the following:

Point X is the location at GEO after 1000km of new ribbon have descended towards the Earth. Point Y is the location 1000km above Earth after 36000km of new ribbon have descended towards Earth. Point Y needs to be able to support the 1000km of ribbon below itself, but Point X needs to be able to support 36000km of ribbon. However, because Point X and Point Y are the same points, the final taper ratio must be very immense.

Alright, I've fixed that thread. I was actually going by Andreas' figure of 0.025G from THIS thread. The 0.002G makes more sense. Looking at Bob's graph at the end of the thread, -0.079G seems to match up pretty well.

It isn't a problem of agreeing on a taper ratio. The problem is that every time you lower the ribbon, the taper ratio must increase, and it will increase exponentially.