Talk:Lunar space elevator

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[edit] Pearson's design

"Jerome Pearson has proposed a design using M5 fibre {typo?} that would weigh only 6,800 kilograms and be capable of lifting 200 kilograms at the Lunar surface; such an elevator could be sent to the Moon with just one launch of the largest existing launchers."

As I read this, 6,800 kg is the mass of the cable only; the total mass of the elevator would be much greater. The article doesn't seem to say how long a cable Pearson envisions, so it's hard to say what the other components of the system--especially the counterweight--would mass.

—wwoods 05

47, 21 Nov 2004 (UTC)

The only reference I had was [1], which didn't specify. But it does sound like it's talking about the bare minimum cable, whereas an elevator would have at least a few extra bits added. (The fibre/fiber thing is just one of the usual British/American spelling differences, not a typo. Since I'm a Canadian I randomly oscillate between the two. :) Bryan 06:25, 21 Nov 2004 (UTC)

I wrote the article... yeah, I'm Canadian, so it's "fibre" here. The 6,800 mass is just the cable, but you could add a climber for a few hundred kg more. So, still within the capablities of current launchers. Pearson figures you could continue to strengthen the cable from material gathered on the Moon. - Fraser Cain, Publisher, Universe Today

Thanks, I've updated the article to make that clear. Bryan 00:47, 17 Dec 2004 (UTC)

Trouble is (unless I grossly miscalculated) the mass of the counterweight has to be orders of magnitude greater than the mass of the cable. Any old mass will do, including the rockets used to carry the elevator components, but still... An "extremely minimalist" system, for highish values of minimalist, eh?

—wwoods 03:03, 17 Dec 2004 (UTC)

--195.178.232.139 12:44, 21 August 2006 (UTC)There sems to have bean some misunderstanding, i wrote thew folowing question to Jerome Pearson:

> Hi I am a PhD student at Lund University (Sweden) in electrical

> engineering; this has nothing to do with my research.

> When I read the articles

>

> http://en.wikipedia.org/wiki/Lunar_space_elevator

> http://www.universetoday.com/am/publish/lunar_space_elevator.html

>

> and then your report to NASA at

>

> http://www.niac.usra.edu/files/studies/final_report/1032Pearson.pdf

>

> I fond some numbers in the articles above that seems to be

> misunderstandings and want

> to sort this out so I can correct the wikipedia article.

>

> The articles say that you proposed a cable with a mass of 6800 kg

> capable of

> lifting 200 kg at the lunar surface. And that this could be launched in

> a single shot with a conventional rocket.

>

> As I read the report you proposed a cable with a mass of 6100 ton

>(6 100 000 kg)

> with a strength (with safety factors) of 2000 N with cross section of

> 0.69 mm^2 at the lunar surface per ribbon and in total tree ribbons.

>

> In both cases the used fibre is M5.

>

> I think the numbers in the articles sounds unrealistic as the mean

> cross section of the ribbon could not be more than 0.025 mm^2. 200 kg

> sounds as someone has "converted" 2000 N to 200 kg using the untrue

> assumption g appreciative = 10.

>

> Have you proposed booth designs or are the articles wrong?

>

> Regards

> Lars Lindgren

I got this answer:

>Dear Mr. Lindgren:

>

>Thank you for your inquiry. I produced the numbers in the report to NIAC,

>but not the numbers in the Wikipedia article. No one consulted with me on

>the Wikipedia article, and I have no idea who wrote it. (This is

>surprising, since I invented the lunar space elevator.) I stand behind my

>NIAC report numbers.

>

>You might also want to consult the discussion and papers referenced on the

>Space Elevator page of the STAR, Inc. website, at www.star-tech-inc.com.

>

>Jerome Pearson, President

>Star Technology and Research, Inc.

>

Based on this i will change the numbers and remove the proposal with a single launch.