has NASA gone crazy with the tether elevator???

[phat tony]

Hi everyone. I am asking has NASA gone crazy with the space tether elevator idea.

I love the idea but I think they have not done the figures.

I hope they succeed because people like us will get to feel the sensation of space and maybe in our life time. Sadly I think if they done the figures they would stop thinking about the tether idea and move on to what I think is better.

They want to build a tether that is 50,000km too 60,000km long so it can be connected to a space station in orbit. They are offering 2 million USD for anyone who can design the material for that tether.

Now I have done some figures and I beg everyone to check them for me.

I looked at their design and it looks to be 1m wide or more and .5m thick.

50,000km x 1000 to get the meters = 50,000,000m long now turn that into cubic meters,

50,000,000 x 1mx .5m = 25,000,000 cubic meters, now into cubic feet

25,000,000m3 x 3.3 = 82,500,000 cubic feet

They are looking for a new material but we can work with Aerogel for this.

Aerogel works out about 200 USD per cubic foot. A new material could cost more or less so lets work with less. We can allow because of who they are they could get it for 100USD per cubic foot

82,500,000 cubic foot x 100usd = 82,500,000,000 USD wow just for materials. Lets allow that they get a cubic foot for 50USD, that = 41,250,000,000 USD still high. They may get lucky and the new material might work out to be very cheap but the next problem is why I think they have gone crazy.

NASA are looking at building the space station in space and then building from the station back towards earth wow.

That means they need to get 82.5 million cubic foot of material into space. The Shuttle used to cost 450 million per mission, so lets say they cut that cost down to 100 million with a new ship. Lets also say that this new super ship would be able to carry 100 cubic foot of material in one mission.

82,500,000 cubic foot divided by 100 = 825,000. That means 825,000 trips or missions just to deliver the material to the space station wow. Now lets allow that 100 million USD is a fair price per mission.

825,000 trips x 100,000,000USD = 8,250,000,000,000 USD wow just to deliver the materials. We all know they will not do it that way, they will construct the sections on earth so you can multiply that price by ten simply because they will fit a lot less on each mission.

One last figure, allow they do 1 mission per week. 825,000 divided by 52 weeks = almost 15,866 years.

What if they make it halve the thickness both ways then half all them figures, I hate to say it but I think they are gone crazy or are pretending because they need that material for weapons of something else.

so has NASA gone crazy or did i do the math wrong?????

[phat tony]

i have done some more research and found i made some mistakes, first they are going out 62,000km but 1m wide by 1mm thick

so here is my new math please check them for me.

62,000km x 1000 = 62,000,000m x 1000

= 62,000,000,000mm x 1mm =

62,000,000,000 mm3 now divide that

by 1000mm = 62,000,000 m3 of materials.

turn that into ft3 = 204,600,000ft3.

Allow 10USD per ft3 = 2,046,000,000USD.

i would guess that it would or could cost more

per ft3 but that is not the big problem.

the shuttles use to cost 450 million per mission,

lets say you can cut that down to 100 million

with a new craft and allow that you could carry

100ft3 of material in one mission.

that works out at 2,046,000 missions @

100million per mission

= 204,600,000,000,000USD. the biggest

problem is time allow you do 1 mission per

week, 2,046,000 missions divided by 52 weeks

= almost 39347 years. the tether is tinner that i was thinking but a lot longer and it looks even harder now. please check my math and post if you agree or think i have made a mistake.

go here to see the video of their plans The Spaceward Foundation

[Grunthos]

There are several good web sites showing detailed calcs for space elevators (a potential viable technology).

First site I pulled off google found here.

HTH

PS It would help if you could stick with SI units...mixing units is most confusing...

[phat tony]

grunthos, you could do the math in any way you like, they are building 62,000km long 1m wide by 1mm thick. i worked it out that way because i understand it. i am not a collage grad i am a ex window designer and fabricator. so use to getting sizes in every way LOL.

i looked at the link you left, interesting but i could not fully understand it. i got the important idea. it looks very like the tether idea but thinner it would still have the same problems, material, getting the material into space and so on. i have been looking at the elevator idea for years. i love the idea of an elevator and i hope they do it in some way. thank you for the reply.

[Grunthos]

Just trying to help mate.

The majority of engineers and scientists in the world use SI - you'll know it as metric. A lot easier to use (base of power 10 etc).

A few people still use "Imperial" (mostly the US).

Nobody mixes up the units. If you do you could end up with a very expensive mistake like the Mars Climate Orbiter fiasco.

[phat tony]

thank you for the input, i understand what your saying and please don't think i was being cheeky with you because i was not. no matter what way you do the figures it still turns a result that looks crazy and i hate to say impossible. not one person has answered the question and i am shocked why. the idea of a elevator to the stars will make space travel for the average person do able and it should be. 62,000,000m x 1 m x .0001m is the figure to be calculated, it adds up to crazy amounts of material and even with all the worlds space agencies involved it would be almost impossible.

[Grunthos]

thank you for the input, i understand what your saying and please don't think i was being cheeky with you because i was not.

No insult intended and none taken (and vice versa).

(I just wished to point out one of the standards by which the likes of scientists and engineers operate.)

[hobbesy]

Presumably, one would make a cable (either in pieces or as one long bit) and take it up into a low earth orbit, drop that to Earth and burn some fuel keeping that in place while they elevator or winch up the rest of the real cable using that as a cable-pull.

[astromerlin]

I think what they might do is make the material so it can be knitted, there's a fair few grannys out there who would enjoy that. Just like a long scarf really!

Seriously though, they have to start making it in space because of the weight problem the longer it gets. They would have to send up the weighted end in geostationry orbit and I suppose as the weight of the tether increasees they would have to increase the mass of the weighted end to compensate.

[Capricorn]

A geostationary orbit is about 35,000Km off the earths surface not 50,000 or more. So that's about 2/3 of the material you are thinking of.

The later posts say 62,000Km so geostationary is a lot less.

Why 1mtr wide ?

If only 1mm thick (by the way 1mm =0.001m not 0.0001 as in one of the later posts) Why 1000 times wider, just seems disproportionate. Would 500mm do it? Half as wide.

Try the Clarke book (I think) Fountains of Paradise.

[phat tony]

hobbesy your idea would work out better in theory, it would need some work but i would say check out the link i posted, they are planning on building from space down.

Capricorn i agree with the height you mention but they are going 62,000km for some reason. i said 1 m wide but they said 3 foot and they are going 1mm thick the extra 0 was a typo:icon_confused: if they got the material they are looking for i think they should go wider for safety even 500mm as you say by 10mm. if they do build it they will have some trouble getting it passed for public use.

astromerlin:D:D:D:D:D:D they could get the grannies out of the shreddies ad:D:D:D:D:D

everyone should look at the video clip in the link, it was provided by NASA for the site.

thank you all for your posts.

Grunthos hi again, i took no offence and also meant none. i have been in construction and design my whole working life and i work in both. as i mentioned above NASA said 62,000km x 1mm x 3 foot so i didn't see any problem:icon_salut:

[perkil8r]

I have a bigger problem with the idea. They've forgoten about gravity! <<< wait a minute while I expand.

Sure there would be more in a zero gravity situation than there would be in the earths gravitational pull, but still there is going to be a lot of pull on there to start pulling the space station back towards earth surely? Never mind the issue of keeping tension in the tether, or stopping the wind from blowing it about etc..... I like the concept, but for me it seems too sci-fi

[Grunthos]

They've forgoten about gravity!

No "they" haven't. (Why would scientists and engineers forget about gravity?).

Please take the time to read some of the basic literature...

[perkil8r]

No "they" haven't. (Why would scientists and engineers forget about gravity?).

Please take the time to read some of the basic literature...

I have, and I still say it's wrong. Centrifugal force requires that the object has weight as well as mass to create kinetic energy. Since there will be no gravitational effect on the "spaceward" end, it can have no weight hence no centrifugal effect.

[JamesF]

It may be best to avoid the term "centrifugal" force as it can be a bit woolly unless you actually define the sense in which you're using it.

Personally I find it hard to believe that the likes of NASA have got their basic physics wrong. I've not read any of the information about it, but I wonder if the way to build it might be to start in geostationary orbit and build downwards, but move away from the Earth at the same time. If they did that then obviously the "space station" end would have to move faster to stay above the same point on the earth which would presumably generate an outward force on the tether. Perhaps that could balance the gravitational force on the tether as it gets bigger as long as the centre of mass remained at the geostationary point. Or something. I don't know. It's late and I'm tired

I don't really care how it works as long as they build it, because I've loved the Fountains of Paradise story since I was in my early teens...

James

[astromerlin]

Weight doesn't have anything to do with centripetal force. Mass and escape velocity is all that is required for the end of the tether. As James mentioned, as the tether is being built the mass at the end of the tether will have to be move into a higher orbit to maintain a geostationary position.

It will be a huge feat of engineering to attempt, if they built it from the top down you'll have the "earth" end of the tether flapping in the breeze for a fair while which will be very unstable.

[dmahon]

Sorry, but there are a few obvious errors in the maths. The ones that really stand at first glance are:

82,500,000 cubic foot x 100usd = 82,500,000,000 USD

You've multiplied by 1000 rather than 100.

25,000,000m3 x 3.3 = 82,500,000 cubic feet

There are 35.3 cubic feet in a cubic metre.

so here is my new math please check them for me.

62,000km x 1000 = 62,000,000m x 1000

= 62,000,000,000mm x 1mm =

62,000,000,000 mm3 now divide that

by 1000mm = 62,000,000 m3 of materials.

Divide by 1,000,000,000 to convert mm3 to m3.

Sorry. There re probably others too.

[phat tony]

dmahon thank you for the help, i did notice some of my mistakes. i am very grateful for your help and i have done the math again, it still works out at a very high cost, not sure how much their new material will cost but i would guess its not going to be cheap. the materials would still take a crazy amount of time to get into space at 100's of billions. could you please do the math for me. 62,000km x 3 ft x 1mm. please??? if you could tell me how many m3 of material it would be super cool.

[calibos]

[JulianO]

could you please do the math for me. 62,000km x 3 ft x 1mm. please??? if you could tell me how many m3 of material it would be super cool.

Converting to metres, 62,000,000m x ~1m x 0.001m = 62,000 m³ or about 0.000062 km³

[dmahon]

To put that into perspective, I think that the shuttle cargo bay held around 300m3 (and the external tank was about 1,200m3).

So probably doable, but not an inconsiderable feat.

[Zakalwe]

A geostationary orbit is about 35,000Km off the earths surface not 50,000 or more. So that's about 2/3 of the material you are thinking of.

The later posts say 62,000Km so geostationary is a lot less.

The centre of mass of the space tether has to be above the geostationary orbit, hence the need for the total length to be a lot longer.

[JulianO]

I think there general idea would be to manufacture it from a hunk of suitable rock using a production machine in orbit. As it extrudes the fibre towards earth, a similar fibre is extruded to balance it in the opposite direction.

[JamesF]

They should float a big solar-powered electromagnet around and "mine" all the debris we've left up there over the last fifty-odd years for raw materials...

James

[Thirdway]

Got to be totally impractical. What do you do with wind shear, ice formation, lightning strikes and the rain which would using the surface as an effective drainpipe.

It's the same reason we don't try and build a bridge from Europe to the USA. In principle it can be done, but it's not cost effective and is effected by the unpredictable natural conditions.

Anyway doesn't ***** Wonker already hold a patent for that idea.