backtop


Print 48 comment(s) - last by reiters.. on Feb 21 at 12:08 PM


Courtesy LiftPort Group
The LiftPort Group has a bold and interesting plan -- to build a massive space elevator before 2020

The LiftPort Group has completed a second round of testing on a prototype space elevator platform that stretches a mile into the sky, which allows a robots to climb and descend the ribbon that is between the two platforms.  The LiftPort Space Elevator would allow a revolutionary way to get cargo and supplies into space -- using a cable thousands of miles long tethered to  an object in geosyncronous orbit.  The company hopes to build the space elevator by the year 2018, but the task will obviously not be easy.  The observation and communication platform that robots climbed is properly dubbed HALE, High Altitude Long Endurance.  HALE was secured in place by several high altitude balloons for over six hours.

The ribbon that will hopefully stretch 62,000 miles from Earth into space will be made of carbon nanotubes weighing less than 1.5 pounds per mile.  Although initial testing was done in Arizona, the space elevator will likely be anchored to an offshore sea platform that will be located somewhere in the Pacific Ocean.


Comments     Threshold


This article is over a month old, voting and posting comments is disabled

So what happens when the cable snaps?
By EODetroit on 2/16/2006 9:34:47 AM , Rating: 2
I wouldn't want to be on the counterweight if the cable snapped... you'd be thrown out into space. I wonder what their contigency plan is. Or maybe all the "equipment" that runs the thing will be placed at the center of gravity, and the counterweight is just dumb weight. But it makes sense to have your equipment as part of the counterwieght if it wasn't for the cable-snapping factor.




RE: So what happens when the cable snaps?
By lamestlamer on 2/16/2006 10:25:36 AM , Rating: 2
The counterweight will eliminate the orbital drag due to corriolis force. The point of the counterweight is that at all times, the weight of the counterweight-tether system is less than the centrifigal force. This will keep tension and will prevent it from being dragged down from a heavy rising load. It will also keep it normal to the surface of the planet, if it is anchored precisely at the equator. The problem is that you need a very heavy counterweight to cause oscillations to be small and slow: however, a very heavy counterweight will be extremely expensive.

I would also like to know how they are going to strand together nanotubes: nanotubes are cheap to make, but excedingly hard to manipulate.


By Micky2Shoes on 2/16/2006 7:40:15 PM , Rating: 2
I don't agree, let me put it another way. The coriolis force is the force needed to add all that extra angular momentum that a payload would have at GEO compared to at the ground. The force will act perpendicularly to the cable. There is no getting around it, you will need to periodically re-boost the counter weight. The only way you wouldn’t would be if there were no net mass transferred up the cable. I do admit that I could be wrong but I am 99% certain of this. I would appreciate enlightenment if you have any to offer but I would like some maths to prove it.

Also I believe coriolis is spelt with a single r (but I may be wrong again).


RE: So what happens when the cable snaps?
By LiamC on 2/16/2006 7:25:56 PM , Rating: 2
Read Red Mars by Kim Stanley Robinson.

What about the falling cable? Not pretty.


By Micky2Shoes on 2/16/2006 7:46:41 PM , Rating: 2
Yes that was a great book. I have seen a study somewhere on precisely this problem. If I remember correctly they concluded that there would be virtually no danger if the cable snapped.


RE: So what happens when the cable snaps?
By Micky2Shoes on 2/16/2006 7:53:56 PM , Rating: 2
Yes you are right but that’s a bit like saying I wouldn't want to be on an aeroplane when the wings fall off. If the thing is properly engineered it won't break.


By EODetroit on 2/17/2006 9:30:38 AM , Rating: 2
Except that in the early days of flight wings were probably torn off all the time. The consequences of which fall back to earth. In this scenario, a failure means you're flung out into space, probably a higher orbit, maybe one that isn't circular any more and will soon result in a re-entry. I doubt you could be flung completely free of the earth, but geo-sync is a long way up, and the counterweight would be thrown out even higher if the cable snapped.

I'm just curious what they plan on doing, or if they plan on it not happening ever.


Date of completion
By smitty3268 on 2/16/2006 3:23:28 AM , Rating: 2
The company hopes to build the space elevator by the year 2018,

Only 12 years away? I don't think there's any chance it will happen that quickly, but this does make me think there might be one in 30 years. Cool. Now my question is, what happens during a hurricane? It seems like strong winds could seriously affect the stability of the station in orbit, and could knock it out of geosynchronous orbit fairly easily. Maybe rocket thrusters are more than enough to compensate though.




RE: Date of completion
By smitty3268 on 2/16/2006 3:26:46 AM , Rating: 2
Hmm, now that I think about it winds would only accelerate or deccelerate the orbit a bit, not move it into a completely different orbit. So not a big problem after all.


RE: Date of completion
By AppaYipYip on 2/16/06, Rating: 0
RE: Date of completion
By goku on 2/16/2006 7:10:44 AM , Rating: 2
Who said this was going to connect us to the moon?


RE: Date of completion
By oTAL on 2/16/2006 12:49:56 PM , Rating: 2
*lolol* He actually thought the counter weight depicted in the drawing was the moon.
I'm trying to contain the laughter in a lab full of ppl...
Damn... they're all starring at me....


RE: Date of completion
By SGTPan on 2/16/2006 8:13:04 AM , Rating: 2
Lol, no what was funny is that you thought the counter weight was the moon! Sorry I'm not trying to be an ass here, but the moon is a little farther than 62,000 miles away.


RE: Date of completion
By SGTPan on 2/16/2006 8:13:52 AM , Rating: 2
Lol, farther... further. Seesh, its too early.


Hmm.
By Souka on 2/16/2006 3:02:15 AM , Rating: 2
Why would the ribbon need to "stretch" 62,000 miles into space?

All gyo-syncronous (don't laugh at my spelling) objects are at approximately 32,000 miles from the Earths surface.

Also, "weighing less than 1.5 pounds per mile" Weight won't be an issue since gravity is very slight over 150 miles over the surface.....but if they need to get 62,000 miles of the stuff into space, that's 46.5 tons to lift... the space shuttle cargo lift is only 32.45tons...hmm... guess it'll be a multiple trip....





RE: Hmm.
By KristopherKubicki (blog) on 2/16/2006 3:18:15 AM , Rating: 2
I'll bite.

Even though you can obtain geosyncronous orbit at 32k miles, you would need a very heavy counterweight to keep the cable in place. You could just extend the cable further into space without the need for heavy, astroid sized counterweights. I am guessing that is the reason they are doing this.

Next, weight IS an issue. There is weightlessness in space, but you're still falling even when in orbit. This is why ISS needs to constantly boost even though it is orbit.

Anyways, the highest GTO of any rocket I know of is 29k lbs. 46 tons is like 4 trips.



RE: Hmm.
By SNM on 2/16/2006 4:05:43 AM , Rating: 2
Once they get the first portion up they can presumably lift more of it up over the elevator itself. Possibly that's even how they intend to do the whole thing.


RE: Hmm.
By Zirconium on 2/16/2006 4:06:15 PM , Rating: 2
quote:
Next, weight IS an issue. There is weightlessness in space, but you're still falling even when in orbit. This is why ISS needs to constantly boost even though it is orbit.

Something in orbit is continuously falling, so weight is not the issue. What is an issue is friction. Space is not a complete vacuum, and satellites do slow down.

However, you are right that the reason they are putting the platform in space farther than geosynchronous orbit (which is actually closer to 36k miles above the surface) is due to the need to for the satellite keep tension on the cable and not fall as something is going up the elevator.


RE: Hmm.
By sandytheguy on 2/16/2006 4:14:09 AM , Rating: 2
At 150 miles up gravity would only be down from 9.8 m/s^2 to 9.1 m/s^2, that's not much of a drop. At 62k miles it would be down to like .04 though.


thunder storms
By kattanna on 2/16/2006 12:19:03 PM , Rating: 2
i take it they are going to do the next test and IF they build the thing in an area where they dont get thunder storms??

if not WOW...the thing is going to be one SUPER lightning rod...





RE: thunder storms
By fhornmikey on 2/16/2006 12:33:08 PM , Rating: 2
Hint: The Elevator is made out of CARBON.


RE: thunder storms
By oTAL on 2/16/2006 1:03:19 PM , Rating: 2
Dude, carbon nanotubes can be conductive... that's one of their greatest characteristics.... they may be... and they may not be.... carbon nanotubes rule!


RE: thunder storms
By Dmitheon on 2/16/2006 1:03:48 PM , Rating: 2
And you're going to prevent moisture from gathering on it how?


Physics
By Bladud on 2/16/2006 8:14:58 AM , Rating: 2
I feel I should correct some of the physics from prior commenters.

Remember that the apparent "weightlessness" of orbit is not weightlessness at all; it is free fall. There is still a force on you, and you are still falling, but you don't notice it because it is a uniform acceleration (remember Einstein's famous lift?). However, the lower parts of the cable, being nearer the earth, are under greater acceleration, which is noticeable. The rope is therefore under (a lot of) tension. So the mass of the cable is very important, because if it were too great no material known to man could withstand the tension created.

The reason they go up to 63,000km is, I imagine, because the *center of mass* of the elevator has to be in geosynchronous orbit, at whatever height, so the counterweight has to be somewhat higher, and the cable proportionally longer.

Hurricanes and so forth are fairly negligable because the cable is very thin and very very heavy, making it correspondingly hard to move. That said, they could cause it to vibrate, like a guitar string, which could be rather unfortunate.

Lastly, using the cable itself to put more of itself into orbit would not work at all, because until it is finished and the counterweight attached, the cable has nothing holding it up (parachutes don't work where there is no atmosphere). I would imagine, however, that by 2018 the new NASA lifter will be ready, and if it isn't, well, transportation is a picayune compared to the problems they would have to solve to get that far.




RE: Physics
By oTAL on 2/16/2006 12:56:36 PM , Rating: 2
For ppl with any questions you should check out the VERY good Wikipedia article about the space elevator. It describes the problems and solutions in detail. Weather IS a problem. And you are all thinking in newtonian physics which is not the best one here. Think Lagrange and use the Earth as an acelerated referencial. At geosinchronous orbit the gravity becomes zero. Below this point it rises up till the ground where it is highest and over this point it is negative. What you need to get is an overall (slightly) negative gravity so that the cable is always under tension - as if something was pulling it from space. It's pretty simple, but you have to understand the concepts of orbit and geosichronous orbit pretty well to even try and understand this.


RE: Physics
By KristopherKubicki (blog) on 2/16/2006 3:45:31 PM , Rating: 2
quote:
The reason they go up to 63,000km is, I imagine, because the *center of mass* of the elevator has to be in geosynchronous orbit, at whatever height, so the counterweight has to be somewhat higher, and the cable proportionally longer.

Kind of. The reason it extends 62k MILES is because the cable will continue to stay in geosyncronous orbit -- even at that great of a distance. The tip of the cable moving that fast is actually what keeps the whole tether stable.... this way you don't need a coutnerweight.

I read someone earlier that the reason why we don't want to use counterweights anymore is because someone calculated that you would need several tons of counterweight at 32k miles.. or you would need just the weight of the cable moving at a much faster speed.... 32k miles further out. its a neat physics problem to work out.


asdf
By konekobot on 2/16/2006 10:37:11 AM , Rating: 2
... makes sense to me.

i like the idea i read about in popular science about space balloons. i forget exactly what the name of the project was. anyways, it involves floating small labs (probably about the size of my one bedroom apt.) into very high stratospheric orbit. they would never completely leave the atmosphere, but the balloons would be high enough to do some interesting observations or possible act as a launching platform for smaller satellites.

keep in mind, i'm not talking about something a small as a zepplin. in the article, these things were half a kilometer in diameter and made of three humongous tubes filled with helium. i think the point here was that it was much cheaper, simpler, and safer than using the shuttle. actually that seems to be the drive behind NASA's "challenge".

"Make Space Cheaper!"




RE: asdf
By Ringold on 2/16/2006 10:57:33 AM , Rating: 2
I dont know why there's even so much debate, especially among common geeks like myself. NASA engineers have figured it out, private engineers have figured it out; the science is there. It can be done; there are only a couple restraints.

Price tag: If NASA does it, expect anything from billions to trillions. Government is wasteful, something said in the first week of a macro or micro econ class. If private business does it, expect the cost to be MUCH less, MUCH more innovative, possibly revolutionary.

Materials: What's the ribbon to be made of exactly? Thats really the missing link. It has to be able to withstand numerous holes getting punched in it from orbital waste, micrometeorites, etc, and there has to be huge margins of safety for possible terrorist attack.

Also, two smaller (easy/non important) issues are safety -- methods of safely landing the crawler in case of cable failure at ANY altitude -- from 10ft to 62,000m. Whole planes have parachutes these days, so thats easy. Also, engineers have pointed out that it'll slowly slow the orbit of the planet down..... After we haul Texas in to space, by a couple seconds per day.

This is like going to Mars. Could be done in 5-10 years, easy. Could have private industry on the Moon with a little push in 5 or less years. It's just a question of 'balls' and vision. NASA is a rounding error in our 2.7 trillion wellfare & military national budget.


Storms etc...
By CurtOien on 2/16/2006 11:38:17 AM , Rating: 2
I had read that the anchor at the earth end of a space elevator could be on an ocean platform that could be moved to avoid severe storms.


Trash
By reiters on 2/16/2006 1:16:42 PM , Rating: 2
Maybe the counterweight could be made out of excess trash from all the major cities. Solves 2 problems at once. :)

Really, how would the mobile base not be lifted up and away with any major changes in tension?




RE: Trash
By nomagic on 2/16/2006 4:21:18 PM , Rating: 2
...

You are kidding me right? The counterweight itself does not cost much money. Sending the counterweight up to the sky does. You misunderstood...


RE: Trash
By reiters on 2/16/2006 4:47:24 PM , Rating: 2
I very much was kidding.

I do wonder what effect it will have on the rotation of the earth. Our planet is highly balanced with our solar syetem and any changes could cause catastrophic results.


extra miles
By PrimarchLion on 2/16/2006 10:13:50 PM , Rating: 2
I don't know if anyone mentioned this, but anything on the elevator that is out past gs orbit(32,000 mi) will be accelerated away from the earth. Very high stresses, but carbon nanotubes can handle it. This is how the elevator could eventually be used as a low-zero fuel launch platform.




RE: extra miles
By PrimarchLion on 2/16/2006 10:24:24 PM , Rating: 2
Sorry for double posting. I haven't read all the comments but as I read I want to comment. To deploy the space elevator requires a satellite be put in geosynchronous orbit. The satellite has two spools of carbon nanotube filament. It unrolls both, extending them at the same rate in both directions. The filament doesn't need to be strong enough to support any payload. When the filament touches down, a robot climbs ups, reinforcing the carbon tube as he goes. He makes several trips to make it strong enough to safely support heavy payloads. Carbon nanotubes are extremely strong.


RE: extra miles
By PrimarchLion on 2/16/2006 10:30:17 PM , Rating: 2
sorry again, i'm excited. I made a mistake, gs orbit is about 36000 km or ~22000 mi. The section of filament above this is probably not as heavily reinforced as the section below, so it is extended further as the bottom part is reinforced. A counterweight would not be required in this case as it would make launching payload difficult.


Tsunamis
By DrDisconnect on 2/16/2006 12:24:38 PM , Rating: 2
Interesting point about the Tsunamis and resonance. Hurricanes or Cyclones might be avoided by an intelligent choice of base location. The base will have to be somewhere on the equator. Actually, I would think that the best location would be the highest stable landmass you could find on the equator but that would cause issues with shipping materials to the base station, risk to adjacent communities, terrorism and local weather (more rapidly variable than mid ocean weather generally).




RE: Tsunamis
By oTAL on 2/16/2006 1:06:00 PM , Rating: 2
You can't do that if you want an even balance and a geosinchronous lift. Check wikipedia for more info. The two best options are a high mountain or a movable platform in the ocean.


This idea is not quite new...
By MarkHark on 2/16/2006 3:11:32 PM , Rating: 2
... but it always had me amazed from the very first day I read about it.

For anyone interested in the subject, I recommend the excellent (fictitious) work by Arthur C. Clarke, "The fountains of Paradise".




RE: This idea is not quite new...
By DEMO24 on 2/16/2006 4:06:38 PM , Rating: 2
And then the day comes when someone programs a satellite wrong and it smacks right into the pole.

I think a more interesting thing is how are they really going to get it all pieced together. Obviously just making the whole elevator is gonna take forever. Then they have to put it all together. I assume they will start in space, but how they hold it in place will be interesting.

I also wonder if this will cast some shadows on the earth? I've read more in depth articles than this one and it's going to be a massive project with many stations and elevators going all over the place. Thus if it does have a counterweight I wonder if it might one day cast a mini-eclipse upon the earth?


Air Plane
By reiters on 2/16/2006 4:49:48 PM , Rating: 2
What if some missguided pilot smacked the cable. There would have to be anti-aircraft equipment available to shoot down any airplanes that get too close. Even if by accident.




RE: Air Plane
By Zoomer on 2/16/2006 10:23:43 PM , Rating: 2
It should be engineered so that any such shocks can be withstood without stress.


Teh End is Nigh...
By Visual on 2/18/2006 12:34:37 PM , Rating: 2
If this thing does work out... it'd be running circles around the Tower of Babylon!
I wonder what the Pope has to say about this.
*grumble* we've lost our fear of god these days... next thing you know, everyone will be speaking the same languge. (Oh wait, no... that'll take at least a couple more generations.)

Boy oh boy how I want to fast-forward a hundred years and have a glimpse around...




RE: The End is Nigh...
By reiters on 2/21/2006 12:08:27 PM , Rating: 2
The goal of the people building the tower of Babylon was to be with God by building a tower to heaven. God shot that down real effectively (assuming you believe the Bible). What they are does not have the intention of finding God, so it I don't think the reference is valid.


Big problem:
By knowyourenemy on 2/16/2006 8:35:05 AM , Rating: 2
Nothing has a perfectly circular orbit, and what is considered a minor change can possibly affect miles of the tether, therefore creating variable slack and maybe even stress damage. I don't see this happening at all.




So like a guitar string huh...
By wjp001 on 2/16/2006 11:25:24 AM , Rating: 2
The resonance would be my main concern because it could potentially act as a guitar string. So hmm, are we going to hear Hells Bells every time God sends a tsunammi across the ocean? :)




Silly Question
By Dmitheon on 2/16/2006 1:01:26 PM , Rating: 2
Silly question: Why anchor it to the ground? It seems like that creates a huge number of complexities. If we're placing a platform out in space and a counterbalance, why not have a platform/counterbalance in the atmosphere as well? Put it at an altitude that aircraft use when they're flying over the storm. The cost of getting it to the platform would be simply that of flying the cargo. This would also let the system be more tolerant of any movement.

You'd have to place the space weight first, but you pretty much have to do that with a sea-level based platform as well. The whole thing seems like an interesting problem, a via solution to which may not exist until we've failed a few times. :-




Space Elevator
By DHunter on 2/16/2006 11:15:50 PM , Rating: 2
This article was a little light. If anybody wants to know more go to www.spaceelevator.com/directory which has links to other articles and sites.




Coriolis Force
By Micky2Shoes on 2/16/2006 9:27:03 AM , Rating: 1
Biggest problem I can see (apart from getting a strong enough cable) is coriolis force. Any object travelling up the elevator would experience coriolis force which eventually would drag the whole thing out of orbit. So you would need to continually boost the counter weight. That being said however you could use this to stabilise the cable (but only if the oscillations were in the plain of the orbit). Also you could use a high specific impulse engine to do the boosting (like an ion engine) which would be a lot more efficient than rockets. So I would say it’s doable but quite tricky.

Coriolis force is a fictitious force arising from the fact the whole system is in a rotational reference frame. It’s given by,

-2m(Omega)xV

where m is the mass of the object, Omega is the angular velocity and V is the velocity of the elevator within the rotating reference frame. Oh and x = cross product not straight multiplication or for that matter the letter x.




“So far we have not seen a single Android device that does not infringe on our patents." -- Microsoft General Counsel Brad Smith











botimage
Copyright 2015 DailyTech LLC. - RSS Feed | Advertise | About Us | Ethics | FAQ | Terms, Conditions & Privacy Information | Kristopher Kubicki