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Future of Space Elevator Looks Shaky
Slashdot ^ | 12/9/8 | kdawson

Posted on 12/10/2008 7:41:35 AM PST by Clint Williams

lurking_giant writes

"In a report on NewScientist.com, researchers working on development of a space elevator (an idea we have discussed numerous times) have determined that the concept is not stable. Coriolis force on the moving climbers would cause side loading that would make stability extremely difficult, while solar wind would cause shifting loads on the geostationary midpoint. All of this would likely make it necessary to add thrusters, which would consume fuel and negate the benefits of the concept. Alternatively, careful choreography of multiple loads might ease the instability, again with unknown but negative economic impacts."


TOPICS: Technical
KEYWORDS: hinduropetrick; indianropetrick; magicropetrick; pipedream; spaceelevator; spaceexploration
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1 posted on 12/10/2008 7:41:35 AM PST by Clint Williams
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To: Clint Williams

So the space elevator is going down?

< ducking >


2 posted on 12/10/2008 7:42:36 AM PST by kimmie7 (***sigh***)
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To: kimmie7
It got the shaft.

(Hey, one bad pun deserves another!)

3 posted on 12/10/2008 7:44:07 AM PST by Jonah Hex ("Never underestimate the hungover side of the Force.")
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To: Clint Williams

How about a space Escalator? ;)


4 posted on 12/10/2008 7:45:45 AM PST by lovecraft (Specialization is for insects.)
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To: Clint Williams
As with all such ideas, the devil is truly in the details.

One such detail, btw, would have been actually deploying the thing in the first place. Turns out that just dropping the cable would require an immense launch campaign.

5 posted on 12/10/2008 7:47:36 AM PST by r9etb
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To: Clint Williams

285,364,283rd floor please


6 posted on 12/10/2008 7:48:56 AM PST by Pistolshot ("Democrats don't show respect, they just demand respect " - ClearCase_guy)
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To: Clint Williams
Coriolis force on the moving climbers would cause side loading that would make stability extremely difficult,

Well there's a twist.

Seriesly, though, from the time I first heard about this I thought the coriolis forces would be a deal-killer for it. Anything that can create a hurricane in the lower levels of the atmosphere is going to be absolutely devastating on a structure that tall.

7 posted on 12/10/2008 7:49:01 AM PST by SlowBoat407 (Do not read this tagline.)
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To: lovecraft

maybe stairs or a ladder....??


8 posted on 12/10/2008 7:49:50 AM PST by tatsinfla
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To: Clint Williams

Simple rockets can probably beat the space elevator in terms of cost. I’m talking about private industry, not government-funded space shuttles.

Though space elevators and other concepts can still be viable on the moon and Mars.


9 posted on 12/10/2008 7:50:17 AM PST by Brett66 (Where government advances, and it advances relentlessly , freedom is imperiled -Janice Rogers Brown)
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To: Clint Williams

This is the equivalent of the “studies” 25 years ago that said Missile Defense would never be possible because “you can’t hit a bullet with a bullet”. It is simply too early in the research cycle to say what is and is not possible when we haven’t even developed the nonofibers that would be the building blocks of the cable.

To point out obstacles that ultimately would have to be overcome is fair. However to issue judgments on project viability before these and other obstacles can be addressed is not science, nor is it engineering.


10 posted on 12/10/2008 7:52:22 AM PST by tlb
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To: tatsinfla
maybe stairs or a ladder....??

The Americans with Disabilities Act requires a space ramp with a slope no greater than 1 inch per foot horizontal distance instead of stairs.

11 posted on 12/10/2008 7:53:24 AM PST by KarlInOhio (11/4: The revolutionary socialists beat the Fabian ones. Where can we find a capitalist party?)
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To: Clint Williams

“determined that the concept is not stable.”

Something I noted when it was first discussed.


12 posted on 12/10/2008 7:59:07 AM PST by edcoil (Looking for a new tagline - do you have one I can use?)
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To: KarlInOhio

well then those ideas are out or the aclu will be on my a**


13 posted on 12/10/2008 7:59:13 AM PST by tatsinfla
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To: Clint Williams

I was wondering how long it would take for reality to set in. And, if the thing ever broke... What a ride THAT would be! Insurance policy would cost a few bucks.


14 posted on 12/10/2008 8:01:04 AM PST by Right Wing Assault ("..this administration is planning a 'Right Wing Assault' on values and ideals.." - John Kerry)
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To: Clint Williams

15 posted on 12/10/2008 8:02:29 AM PST by mysterio
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To: Clint Williams

They should start with a stairway to heaven.


16 posted on 12/10/2008 8:02:34 AM PST by weegee (Sec. of State Clinton. What kind of change is it to keep the Bush-Clinton-Bush-Clinton Oligarchy?)
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To: Clint Williams

A really long rope? Maybe?


17 posted on 12/10/2008 8:04:36 AM PST by naguszed
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To: tatsinfla
How about a giant space pulley system?


18 posted on 12/10/2008 8:06:15 AM PST by weegee (Sec. of State Clinton. What kind of change is it to keep the Bush-Clinton-Bush-Clinton Oligarchy?)
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To: Pistolshot
285,364,283rd floor please

No matter how high, there will always be somebody that wants to get off on the second floor...

19 posted on 12/10/2008 8:07:16 AM PST by rjsimmon (1-20-13)
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To: naguszed
A really long rope? Maybe?

Mmmm. Could BE!

20 posted on 12/10/2008 8:07:16 AM PST by weegee (Sec. of State Clinton. What kind of change is it to keep the Bush-Clinton-Bush-Clinton Oligarchy?)
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To: rjsimmon

In case of fire, please use stairs.


21 posted on 12/10/2008 8:08:05 AM PST by weegee (Sec. of State Clinton. What kind of change is it to keep the Bush-Clinton-Bush-Clinton Oligarchy?)
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To: Clint Williams
Slowing the climb would allow the space elevator to be drawn back to its stable point, perfectly vertical above the Earth's equator. But this could also make trips into orbit agonisingly slow, adding nine days or more to a climb that – at several hundred kilometres per hour – might already take about 15 days.

Well, 100 km/hr is a 15 day journey, if you're talking several hundred km/hr, then you're cutting that down to five days.

Which is, admittedly, a heck of a lot slower than I imagined it would be, but the supposition is that for stability sake, they're starting to think maximum speed would be about 60 km/hr, which would mean the 36,000km journey would take 25 days.

However, humans tend to go to low earth orbit - the space station's at 350km from the earth - 60km/hr to there would only take about six hours, a far more practical situation, though still one heck of an interesting onramp since all the rest of the traffic is going 27000km/hr faster than you are.

22 posted on 12/10/2008 8:09:38 AM PST by kingu (Party for rent - conservative opinions not required.)
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To: kimmie7
Bellhop "You're going down"

Peyton Manning..."Yes I am. Fourth floor."

23 posted on 12/10/2008 8:10:33 AM PST by Deaf Smith
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To: weegee

along the lines of a dumbwaiter maybe...??...hmmmm (sorry to all waiters and waitresses)


24 posted on 12/10/2008 8:16:02 AM PST by tatsinfla
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To: Clint Williams; Titan Magroyne; KevinDavis

Told ya so / Wayback machine ping.

I was involved in a huge troll war on another forum years ago arguing just these concepts. I advocate a space catapult constructed in high mountains instead, which would be much more effective, easier and cost friendly for moving large cargo.

It was basically an Arthur C. Clarke (space elevator) VS. Robert A. Heinlein (space catapults) Science Fiction debate that turned nasty.


25 posted on 12/10/2008 8:21:06 AM PST by Drumbo ("Democracy can withstand anything but democrats." - Jubal Harshaw (Robert A. Heinlein))
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To: Drumbo
was the undercard a Dune vs. Foundation battle?
26 posted on 12/10/2008 8:25:10 AM PST by Hegewisch Dupa
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To: Hegewisch Dupa

Asimov beats Herbert hands down. No contest really.


27 posted on 12/10/2008 8:26:46 AM PST by Drumbo ("Democracy can withstand anything but democrats." - Jubal Harshaw (Robert A. Heinlein))
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To: kingu
However, humans tend to go to low earth orbit - the space station's at 350km from the earth - 60km/hr to there would only take about six hours, a far more practical situation, though still one heck of an interesting onramp since all the rest of the traffic is going 27000km/hr faster than you are.

Yes, admittedly, you'd still have to transfer from the Beanstalk (which, like a very tall tower, is effectively motionless relative to the Earth's surface) to the untethered space station whizzing by (at about 8 km per sec) in low Earth orbit.

People currently "tend" (a curious choice of words on your part) to go to LEO not because there's anything intrinsically interesting there, but rather only because it's the nearest/lowest/cheapest "spot" which is nonetheless already in "true" space.

I, personally, have no problem with a long, stately "drive" into geostationary orbit. Who's in a hurry?

Regards,

28 posted on 12/10/2008 8:27:22 AM PST by alexander_busek
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To: rjsimmon

Can you imagine hitting all the buttons for the rest of the floors above you before you get off on yours? That sucker would never come down.


29 posted on 12/10/2008 8:29:15 AM PST by Pistolshot ("Democrats don't show respect, they just demand respect " - ClearCase_guy)
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To: weegee

The Babelians tried that once, and now they’re set to try it again. The thing sounds goofy on the face of it, but if God allows it - who am I to say?


30 posted on 12/10/2008 8:31:37 AM PST by Twinkie (TWO WRONGS DON'T MAKE A RIGHT!!!)
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To: Drumbo

agreed


31 posted on 12/10/2008 8:36:46 AM PST by Hegewisch Dupa
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To: Pistolshot
285,364,283rd floor please

With my luck, somebody'd fart at about the 10th floor.

Only 285,364,273 floors to go....

32 posted on 12/10/2008 8:41:17 AM PST by uglybiker (1f u c4n r34d th1s u r34lly n33d 2 g3t l41d)
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To: uglybiker
With my luck, somebody'd fart at about the 10th floor.

Ok, now I have TWO 27 inch monitors to clean off the sprayed coffee when I read this.

Thanks.

33 posted on 12/10/2008 8:47:34 AM PST by Pistolshot ("Democrats don't show respect, they just demand respect " - ClearCase_guy)
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To: Jonah Hex

Very punny.

lol


34 posted on 12/10/2008 9:01:27 AM PST by kimmie7 (***sigh***)
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To: r9etb

I’m no physicist, but isn’t the Coriolis force a fictitious force? Its only an observation of behavior by the reference of being in a rotating environment?

I understand that as the elevator climbs the ribon, it will continue to need to move at an ever faster rate of speed (keeping up with the rotation of the ribbon) in the direction of the earths rotation, but the drag of its movement I would think be minimal relative to the overall system.

I assume I am just missing something.


35 posted on 12/10/2008 9:13:01 AM PST by HamiltonJay
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To: HamiltonJay

36 posted on 12/10/2008 9:15:45 AM PST by Scythian
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To: HamiltonJay
I’m no physicist, but isn’t the Coriolis force a fictitious force? Its only an observation of behavior by the reference of being in a rotating environment?

The coriolis effect is real. Look at the rotation direction of a hurricane in the northern and southern hemispheres, for example, or the direction of "swirl" as water flows down the drain.

The reason why is, the Earth really is a rotating environment; and the acceleration is "fictitious" only from the perspective of an inertial reference frame.

As for "small forces" -- in space, small forces have significant effects because there's no friction to moderate those effects. Thus, solar radiation pressure will be a big deal.

Also, you need to realize that the reason a space elevator would work at all, is because the center of mass of the system is in a geostationary orbit. If you attach something massive to the tether and start cranking it up, the center of mass will be displaced downward, and thus the tether would want to move forward. The response is to crank something upward to keep the center of mass approximately the same; or to fire thrusters to adjust.

37 posted on 12/10/2008 9:24:12 AM PST by r9etb
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To: Clint Williams

Solution might be to build a smaller scale elevator first on the Moon if you don’t trust your computer modeling on the Earth one.. Current materials should be strong enough for that and the risks of failure are far less. Work out the theoretical bugs there and then put the carbon nanotubes to work for the earth one. Of course such would be the most expensive engineering model in history, but conceptually it could help and would eventually make it much cheaper to get lunar raw materials into space for future construction products on SF time lines.


38 posted on 12/10/2008 11:08:04 AM PST by JohnBovenmyer
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To: r9etb
The coriolis effect is real. Look at the rotation direction of a hurricane in the northern and southern hemispheres, for example, or the direction of "swirl" as water flows down the drain.

Actually, the Coriolis effect doesn't affect anything as small as a drain - it only noticeably affects large-scale phenomena such as hurricanes (as you also point out). In your sink, the direction of swirl is determined by the design of the fixture, and it's entirely possible to have drains in your house that swirl in both directions.

39 posted on 12/10/2008 11:09:14 AM PST by RansomOttawa (tm)
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To: alexander_busek

The point of the space elevator is to launch payloads to interplanetary space rather than to earth orbit, although it would suffice for geostationary orbits.


40 posted on 12/10/2008 11:13:00 AM PST by RightWhale (We were so young two years ago and the DJIA was 12,000)
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To: HamiltonJay
isn’t the Coriolis force a fictitious force?

Sure, but it is the sideways force upon you when you move from the equator to the pole and is a major force in atmospheric modeling.

41 posted on 12/10/2008 11:17:42 AM PST by RightWhale (We were so young two years ago and the DJIA was 12,000)
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To: Clint Williams
"The Ringworld is unstable! The Ringworld is unstable!"
42 posted on 12/10/2008 12:48:23 PM PST by Question_Assumptions
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To: markman46; AntiKev; wastedyears; ALOHA RONNIE; RightWhale; anymouse; Brett66; SunkenCiv; ...

43 posted on 12/10/2008 2:33:42 PM PST by KevinDavis (Thomas Jefferson: A little rebellion now and then is a good thing)
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To: Clint Williams

Somehow this failure must be connected with global warming in the future.


44 posted on 12/10/2008 3:39:56 PM PST by Aussiebabe
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To: r9etb
Also, you need to realize that the reason a space elevator would work at all, is because the center of mass of the system is in a geostationary orbit. If you attach something massive to the tether and start cranking it up, the center of mass will be displaced downward, and thus the tether would want to move forward. The response is to crank something upward to keep the center of mass approximately the same; or to fire thrusters to adjust.

Two words: Ballast Weight.

Increase it slightly so the centre of mass is always above geostationary orbit position. Tension on the cable is slightly greater, but it's always stable.

45 posted on 12/10/2008 5:12:27 PM PST by Oztrich Boy (Zero tolerance does not mean putting up with Barack for the next 4 years - that's just punishment)
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To: JohnBovenmyer
Solution might be to build a smaller scale elevator first on the Moon if you don't trust your computer modeling on the Earth one..

A Moonstalk would have lower stress on the cable, but because of the moon's lower rotation, it would have to be on much larger scale (maybe 4 times as long as an Earthstalk) - and the lower cost of lifting mass of the surface by reaction drives or surface catapult means it's not the economic way.

Now a MarsStalk is another matter: both shorter and lower stressed than an Earthstalk.

46 posted on 12/10/2008 5:24:43 PM PST by Oztrich Boy (Zero tolerance does not mean putting up with Barack for the next 4 years - that's just punishment)
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To: Oztrich Boy
Increase it slightly so the centre of mass is always above geostationary orbit position. Tension on the cable is slightly greater, but it's always stable.

Let's look at that. As the CM is above GEO, it will want to fall back. The tether has fixed length, so it will pull the CM downward. The net effect would most likely be that there's a slight catenary curve to the tether, with the CM at GEO, and you're back to the same situation. And that's just with the system itself -- once you add moving masses along the tether, the whole thing gets more dynamic.

47 posted on 12/10/2008 6:11:32 PM PST by r9etb
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To: r9etb
Let's look at that. As the CM is above GEO, it will want to fall back

Not if it's moving faster the orbital velocity for the altitude (as it would be)

48 posted on 12/10/2008 6:28:24 PM PST by Oztrich Boy (Zero tolerance does not mean putting up with Barack for the next 4 years - that's just punishment)
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To: HamiltonJay
I’m no physicist, but isn’t the Coriolis force a fictitious force? Its only an observation of behavior by the reference of being in a rotating environment?

Im no physicist either but there conservation of angular momentum. This means that as the elevator moves up, its angular momentum will make it slow down relative to the rotation of the earth. Its what drives the Coriolis effect and what makes an ice skater spin faster when they pull in their arms and legs.

49 posted on 12/10/2008 6:29:24 PM PST by Tramonto (More broker for you money.)
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To: Oztrich Boy
Not if it's moving faster the orbital velocity for the altitude (as it would be)

I don't think so. The CM is still in orbit. FOr orbits, faster=higher=backward. I don't think a tether will change that.

50 posted on 12/10/2008 6:38:51 PM PST by r9etb
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