Cable Car to Space

NewScientistSpace ^

[timer]

I see you've been thinking of space things for quite awhile. Instead of rockets getting to and from the asteroid belt, towing one to a Lagrangian point, etc, try the magnetic sail concept instead. This is where a thin ring of superconductor, say a km in diameter, is held by strings to a central cabin which can shift around somewhat within the circle of the ring(change its c.g. a bit). The ring su-co then makes its own dipole magnetosphere which is then pushed inward or outward by the magnetic field of th solar wind, a magnetic sailing ship if you will. This is a 20 year old idea, ingenious, but again, if it ain't a ROCKET it AIN'T...as far as NASA is concerned...

[Netheron]

You need try decaffinated coffee. Just because I put a Langmuir probe in a plasma doesn't mean that the potential will change.

[Netheron]

1) If its a near perfect insulator, the potential will not find a way along it. That's what the definition of an insulator is.

2) If the cable itself is a 'reasonable' insulator, then absolutely nothing will happen, since current won't flow along it. 400,000V is a very wimpy electric field when spread out across 100,000m. 4 V/m is the type of field that most electrical engineers consider 'background noise'.

3) The ions in the ionosphere are fairly diffuse. In addition, the mean free path is very long. The resistance of the ionosphere itself will prevent much activity as well.

4) Please learn basic Electrical Engineering before holding forth on subjects like this. Your ability to type in capital letters doesn't hide that you are completely ignorant.

[Sundog]

Thanks for the concept.

That would be a handy device, especially where su-co can now be made of materials that don't need cooling in space.

[hinckley buzzard]

I've been in contact with liftport for a few months now,

Just out of curiosity, have they been in touch with you in return?

[timer]

Try running that by federal environmental committees...also, water vapor will condense on the cable, what happens then? No, you're the type that can't do analysis very well, and gets a lot of people killed jacking your learning curve up to a positive slope. Fooling with the entire world's weather is not a game for children...if liftport can't answer the possible lightning effects of a skyhigh cable to all concerned...perhaps nature in the form of a red sprite will settle the issue...

[timer]

Oh yes, I'm on their mailing list. Michael Laine has gotten back to me on a couple of occasions. I keep reminding them that this lightning problem isn't minor. If there is even the slightest chance of short circuiting the earth-ionosphere capacitor and screwing up the entire weather-balance of the earth...the FBI/MIB/CIA, etc will be on to them in a heart beat. If they're lucky they'll only get a one day sentence in the fondler's shop of tender mercies... Seriously though, their best shot is not a pie-in-the sky space elevator, it should be 1000' high tethered balloons for area lighting over cities, microwave towers, cell phone towers, sky diver platforms; things of that nature. To wit, they're not going to last long as a teeny bopper science fair dreamsville project(the Hindenberg blimp was 70 years ago), every business has to MAKE MONEY if it's going to stay in business, yes? So that's where I suggested they go : practical applications...

[KevinDavis]

[KevinDavis]

It is not costing you a dime...

[timer]

For your education : Feynman's Lectures(of 1963) chapter 9 : Electricity in the Atmosphere. The potential distribution above the earth. Fig 9-1 : E=100V/m. Do you know who Richard D. Feynman was? Second item : on a recent shuttle mission a km long tether line was tested out in space. Purpose was to see how 2 spinning masses at the ends could maintain 1 g conditions with a pure tension(and lightweight)rope between them. The tether line got FRIED, it looked like crispy critters french fries they said, so maybe you had better do some more research on your proposed space elevator cable...

[SunkenCiv]

Space-elevator tether climbs a mile high
New Scientist | 2/15/2006 | Kimm Groshong
Posted on 02/15/2006 10:24:11 AM PST by Neville72
http://www.freerepublic.com/focus/f-news/1579113/posts

[meanie monster]

Thanks For the Ping a ling!!!!!

[Vaquero]

you jest but this is physically do-able and obeys the laws of simple physics. Unlike Time travel.

[Netheron]

1) Yes, I know who Feynman was. And 100V/m is still chump change.

2) a) It wouldn't have happened if they used a non-conductive cable.
b) That was a cable with a ground velocity of 18000 mph. The resulting voltage was due to the induction effects of the cable with the magnetic field of the earth.

3) The answer is really simple... use an insulating cable.

Yes, I know who Feynman is, but gratuitously quoting out of freshman science texts is not very impressive. Until you stop talking about voltage and start talking about Amperage down the cable and Watts dissipated per unit tether length, you are making no sense at all.

[B-Chan]

While meaning no insult, I must point out tha your knowledge of the facts in this matter seems to be lacking. First, in the case of the Shuttle tether, the spacecraft (and tether) were co-moving in Earth orbit. As they orbited the Earth, they were in motion with respect to the magnetic lines of force connecting the Earth's north and south magnetic poles, thus converting kinetic energy to electrical voltage through the conductive cable (in the manner of an electrical generator) and inducing a current in the tether wire. A space elevator would of course be stationary with respect to the Earth's magnetc field, and therefore would generate no voltage or current from its kinetic energy.

As far as the voltage differential between the base of the elevator and the portion running through the ionosphere, "it is correct that there are substantial electrical potential in Earth's atmosphere. However... a quantitative analysis of the situation [reveals that] the currents that will flow through the ribbon will be minimal due to the resistance of the ribbon, cross-sectional area of the ribbon, the distance the potentials are separated by, and the poor coupling between the ionosphere and the ribbon" [source].

For the record: I do not like the term "space elevator". I think we should call the proposed system a "space railway" instead.

[Jotmo]

Even if the cable wasn't and insulator, insulating 400KV from ground is a simple matter. It's done all day, every day in thousands of locations, in ALL types of weather all over the world.

[timer]

I just got the weekly report from the liftport group. In their recent mile high balloon/tether test they got a severe ZAP...hello from Ben Franklin with his kite and key experiment 200 years ago...what you fail to take into account is water vapor condensing on your carbon fiber insulator-tether. Then there's auroras and changing electric/magnetic fields in the magnetosphere......So its still a dice game and you're playing with the entire world's weather system(electro-potential gradient), are you prepared to be grilled before a congressional committee with your experiment? Once it gets out that you're fooling with everyone's weather(no more lightning as a natural force)you might find yourself on a criminal referral list. Odds are though that your tether-cable will get crisy critter-ed by nature...and you finally get serious about EMSL and other STS concepts...

[SteveMcKing]

Were I a gambling man, I think equal investment in new modes of lift vehicles would pay off "faster, better, cheaper" than this particular dream.

But I don't believe in betting!

[timer]

You miss the point : running any kind of cable from grade to 22,500 miles in geo-stationary orbit is serious business. You're not just grounding out lightning strikes, you're grounding out the entire earth-ionosphere capacitor, drastically changing the entire earth's weather. You have water vapor condensing on your carbon-fiber nanotube insulator, thus a conductance path. Then you have reactive oxygen and nitrogen atoms attacking any material in LEO(well documented), your cable gets plasma crispy crittered very quickly. Also, being a solid path for auroras/electron flows the tether cable acts as a better conduit than the ionosphere....no, you space elevator enthusiasts had better do some more homework before you ask for megabucks to do this pie-in-the-sky test with the entire world's weather systems. The EPA will take a very dim view of it until iron-clad proof is supplied.

[timer]

You still haven't addressed the issue of water vapor condensing on the tether. Then there's the well documented fact of reactive oxygen and nitrogen atoms plasma-ablating materials in LEO. Then you have auroras, changing field lines in the dynamic magnetosphere...what you're proposing with your space elevator could drastically change the entire world's weather and magnetosphere(which protects us from solar/cosmic radiation). Are you prepared to be hauled before congressional committees by the EPA/FBI to explain yourself on a criminal referral? This is deadly serious business pilgrim, not a teeny bopper science fair project. And liftport just sent the latest report on their mile high test in AZ, they got a big ZAP...hello from Ben Franklin 200 years ago and his kite/key lightning test...