Space elevator ? How can it work?

[RonRyan85]

I have been reading about the so called "SPACE ELEVATOR" in various articles in the news
papers and magazines and reading that in a contest recently a company won a $900,000.
prize as their creation climbed a mile long cable suspended from a helicopter in under 4 min.
I understand that this "Space Elevator" if it works is supposed to transport materials into
space (The Space Station ?) The full size unit would be a cheaper way to send food,water and
equipment into space ...but will someone explain how it would work ? IF the space Station
were attached to the end of the cable and it is going at 17,000 miles an hour in Earth orbit, how can the Space Elevator be hooked up and have any chance of working ?

Please forgive me if this subject has been talked about before this. I searched for SPACE
ELEVATOR and only got " ? lifter".

 

[minger]

Wikipedia has a failry thorough article
http://en.wikipedia.org/wiki/Space_elevator

 

[Mech_Engineer]

I have been reading about the so called "SPACE ELEVATOR" in various articles in the news
papers and magazines and reading that in a contest recently a company won a $900,000.
prize as their creation climbed a mile long cable suspended from a helicopter in under 4 min.

The point is that the winning design climbed the cable using power transmitted to it by a laser on the ground. Climbing the cable of a space elevator is fairly straightforward, but getting power to it can be difficult, and one possibility is a ground-based laser station which beams power to the elevator as it climbs the cable. This proof-of-concept showed it might be in the realm of possibility.

As it is we don't have a way of creating a cable strong enough to act as a space elevator, and overall the elevator power system is a small one of many problems that need to be addressed before it becomes a possibility.

 

[WhoWee]

I would think maintenance/replenishment of the strand would be key.

 

[Equate]

IF the space Station
were attached to the end of the cable and it is going at 17,000 miles an hour in Earth orbit, how can the Space Elevator be hooked up and have any chance of working ?

It wouldn't be hooked up to the station. It would be a geostationary platform from which the cargo were to be distributed.

 

[RonRyan85]

OK. Thanks for all the answers. I was thinking they were trying to get the thing from
a parking lot up into something already in space.

 

[DaveC426913]

OK. Thanks for all the answers. I was thinking they were trying to get the thing from
a parking lot up into something already in space.

No, they drop the cable from the orbiting satellite to the ground. It's stationary because the satellite is in geostationary orbit.

Now that you've got the cable in place, you have to start getting payloads up it. That's where there's a lot of research. A payload that needs to climb 35,000km is going to be mostly motor. So they're looking at ways of keeping the motor on the ground. thus, lasers.

 

[mugaliens]

I understand that this "Space Elevator" if it works is supposed to transport materials into
space (The Space Station ?)

...

IF the space Station
were attached to the end of the cable and it is going at 17,000 miles an hour in Earth orbit, how can the Space Elevator be hooked up and have any chance of working ?

It couldn't, as once the paylods arrived at the proper altitude, they'd be woefully shy of the ISS' orbital velocity.

The point is that the winning design climbed the cable using power transmitted to it by a laser on the ground.

While that's fine for a 1 mile cable, the question is how well will this method work at 180 nmi distant?

Now that you've got the cable in place, you have to start getting payloads up it. That's where there's a lot of research. A payload that needs to climb 35,000km is going to be mostly motor. So they're looking at ways of keeping the motor on the ground. thus, lasers.

The motor? Or the power supply?

With solar power and a worm drive, you could easily take your time, perhaps a couple of days, working your way up the cable.

My concern involves the wear and tear on the cable!

 

[FredGarvin]

How about the fact that the cable is still only available in La La Land? That seems like a pretty big concern to me.

 

[DaveC426913]

How about the fact that the cable is still only available in La La Land? That seems like a pretty big concern to me.

As Arthur C. Clarke said: the space elevator will be built ten years after everyone stops laughing.

A lot of people aren't laughing.

 

[Brian_C]

How about the fact that the cable is still only available in La La Land? That seems like a pretty big concern to me.

Academic scientists and engineers don't care about such practical matters. They need to hype up their pet projects so they can get tenure and government funding.

 

[Cyrus]

Academic scientists and engineers don't care about such practical matters. They need to hype up their pet projects so they can get tenure and government funding.

Do you have a source for this statement?

 

[FredGarvin]

I have seen some pretty ridiculous things funded in my short time, so I can appreciate that aspect.

Trust me Dave, the people who aren't laughing are the bean counters and the wackos that will have NOTHING to do with being responsible for trying to build this monstrosity. I have yet to see one credible source talk about its feasibility. It's a nice idea though.

 

[Jobrag]

Arthur C Clark's The Fountains of Paradise gives a good description of how a space elevator might work.

 

[DaveC426913]

Trust me Dave, the people who aren't laughing are the bean counters and the wackos that will have NOTHING to do with being responsible for trying to build this monstrosity. I have yet to see one credible source talk about its feasibility. It's a nice idea though.

No, what I'm trying to tell you is that there are whole communities of scientists and engineers that have banded together to solve these problems. I suppose if I directed you to these that would be pretty much the last word on the subject...

 

[FredGarvin]

No, what I'm trying to tell you is that there are whole communities of scientists and engineers that have banded together to solve these problems. I suppose if I directed you to these that would be pretty much the last word on the subject...

Yeah. Please do. When I see a credible engineering source, I'll believe it.

 

[Brian_C]

I remember watching a seminar by a Ph.D physicist who claimed that we should put solar panels on the Moon and beam the energy back to Earth using microwaves. He didn't spend one second talking about practical economic or engineering realities. Projects like the space elevator and fusion power are being promoted by these kinds of people. They could care less if their pet projects ever materialize, as long as they can publish lots of papers and scam some money out of DARPA.

 

[mugaliens]

How about the fact that the cable is still only available in La La Land? That seems like a pretty big concern to me.

That's certainly a major issue, Fred!

I would offer that no systems are developed once all the technology is in place. From the SR-71 to Apollo to the Space Shuttle, Pegasus... Much of the technology was developed along with the system. Most of the time that involved refinement of existing technology until it worked as designed and met specs.

Not always, however, particularly with R&D efforts. Often, there's no specific project in mind, but someone gets an idea, and runs with it so long as funding holds out. They often shelve whatever they have at that point, but occasionally a need will surface, either inside or outside the firm, and the technology is used/rented/sold.

Carbon nanotubes are real. They do exist. However, we have not yet developed any appreciable means of making them into high-tension cabling. We're not even certain that nanotubes are the best solution. Time will tell.

 

[DaveC426913]

Projects like the space elevator and fusion power are being promoted by these kinds of people. They could care less if their pet projects ever materialize, as long as they can publish lots of papers and scam some money out of DARPA.

That does not detract from respectable organizations working on it.

There are crackpots working on space flight too. Does it then follow that "space flight" is crackpottery?

 

[DaveC426913]

On the other hand, looking around, I'm not finding as much as I thought I would.

ISEC seems to be the biggest organization, and it's just a half-dozen guys. Maybe interest has died away in the intervening years.

This makes me sad.

 

[russ_watters]

I would offer that no systems are developed once all the technology is in place. From the SR-71 to Apollo to the Space Shuttle, Pegasus... Much of the technology was developed along with the system. Most of the time that involved refinement of existing technology until it worked as designed and met specs.

The steps from one to the other there are not that big and the SR-71 used a surprising number of off-the-shelf components. It was innovative, but a space elevator would require a quantum leap in materials technology. It is akin to suggesting the Wright Brothers should have tackled supersonic flight for the Flyer II.

On the other hand, looking around, I'm not finding as much as I thought I would.

ISEC seems to be the biggest organization, and it's just a half-dozen guys. Maybe interest has died away in the intervening years.

This makes me sad.

I know it sucks to have your bubble burst, but Fred really is talking about reality here. The idea of a space elevator is just science fiction. Even when people "research" the idea or do these little demos with cables hanging out of helicopters, serious scientists and engineers know that they are just publicity stunts. There isn't anything coming anywhere near to approaching reality in these ideas.

I'd be surprised if we get a space elevator in my lifetime (I'm 34) and if we get one in the next 20 years, I'll eat my telescope.

 

[DaveC426913]

...a space elevator would require a quantum leap in materials technology.

On the contrary, it would require a large leap in materials technology...

In real physical systems a 'quantum leap' is not necessarily a large change, and can in fact be very insignificant. ... In the popular sense, the term is usually applied to mean a large or significant change, which is thus not strictly correct."

Sorry Russ. I hadda. Someone on TV used this the other day but my yelling at the screen didn't cause them to retract it.

I'd be surprised if we get a space elevator in my lifetime (I'm 34) and if we get one in the next 20 years, I'll eat my telescope.

Perhaps there's some confusion about timelines here. I wasn't suggesting it would happen in the next 20 years. Not even the next 40.

I suppose, upon reflection, an engineering feat that is 40 years in the future is hardly distinguishable from science-fiction.

 

[russ_watters]

On the contrary, it would require a large leap in materials technology...

Sorry Russ. I hadda. Someone on TV used this the other day but my yelling at the screen didn't cause them to retract it.

You yelled at your TV over a bit of slang? Ok...

How 'bout this: we're light years away from having the this type of technology.

Perhaps there's some confusion about timelines here. I wasn't suggesting it would happen in the next 20 years. Not even the next 40.

I suppose, upon reflection, an engineering feat that is 40 years in the future is hardly distinguishable from science-fiction.

Indeed, if a piece of technology lies 40 years in the future, is science fiction because you can't schedule scientific advances. The horizon of technology just isn't that far. Consider how long people have been saying that fusion is right around the corner! (at least fusion is forgivable since it could so profoundly change society - it would be a real game changer)

So if you see that this is that far over the horizon, I don't get how these little publicity stunts seem worthwhile to you. No money should be spent on the issue right now. Carbon nanotubes are going to advance whether the space elevator is on the table or not. In 20 years, maybe they'll have come far enough to start considering the question.

 

[mugaliens]

I suppose, upon reflection, an engineering feat that is 40 years in the future is hardly distinguishable from science-fiction.

Well, there I was in 1969, watching Star Trek, Superman, action-adventure movies, dreaming of rockets, airplanes, new materials, and putting them all together in a science presentation called "Moonopolis."

Original, huh?

I'm still doing much the same.

 

[FredGarvin]

I would offer that no systems are developed once all the technology is in place. From the SR-71 to Apollo to the Space Shuttle, Pegasus... Much of the technology was developed along with the system. Most of the time that involved refinement of existing technology until it worked as designed and met specs.

Be specific. Apollo and the SR had much of the ideas in place. Yes, things had to be figured out, but, in the case of the SR, there was no new materials being dreamed up. They pioneered manufacturing of titanium, but it was already in existence. There was nothing on the SR that required the leap in technology that the elevator would require. Apollo was built off of a lot of small, incremental improvements from the Mercury program.

Not always, however, particularly with R&D efforts. Often, there's no specific project in mind, but someone gets an idea, and runs with it so long as funding holds out. They often shelve whatever they have at that point, but occasionally a need will surface, either inside or outside the firm, and the technology is used/rented/sold.

Trust me, ESPECIALLY with R&D efforts (I work in R&D), to get funding there has to be more than an idea. One has to have a clear road map for what they are looking at and supporting theory. This is not R&D. This is fantasy that some people are tying wishes to. Not that I have been scouring data, but I can not recall anyone posting something to do with the elevator that is technologically feasible right now or in the next 20 years.

Carbon nanotubes are real. They do exist. However, we have not yet developed any appreciable means of making them into high-tension cabling. We're not even certain that nanotubes are the best solution. Time will tell.

There is absolutely NO experience in using nanotubes. We have some small scale materials testing with limited details. We have no way of manufacturing in sight and we have no methods of forming things from those materials. We had a thread while back in which we calculated the required amount of time to manufacture a small cable for an LEO elevator. It was not a nice number. That is a very far cry from what level of knowledge is required to actually implement it in a design. The materials area alone will require huge money and time investments. It will most likely happen, not in ours or my kids' lifetimes though.

 

[Cyrus]

Be specific. Apollo and the SR had much of the ideas in place. Yes, things had to be figured out, but, in the case of the SR, there was no new materials being dreamed up.

Um...yes, there was. The fuel and rubbers were specially made, as were the paints. Every piece of that airplane had to be one-off made.

I'm not saying it was on the same level as a space elevator, only that your example is a bad one. You should have said the U-2.

Apollo was built off of a lot of small, incremental improvements from the Mercury program.

Can you name those small incremental improvements? My understanding is that this is not the case (though I could be wrong).

 

[FredGarvin]

Um...yes, there was. The fuel and rubbers were specially made, as were the paints. Every piece of that airplane had to be one-off made.

I'm not saying it was on the same level as a space elevator, only that your example is a bad one. You should have said the U-2.

I think it's perfectly applicable. While SR-71 was a technological feat, but it pales in what is required for the space elevator in many ways.

The SR-71's materials were modifications to existing materials. Titanium and its alloys were already in existence. The tough part was getting it from the Russians. JP-7 was a modification of existing kerosene based jet fuels. It was not a fuel "from scratch." It had a different refinement process in order to limit its chemistry which gave it better thermal stability and a slightly lower freezing point and different additives, all, to my knowledge, were in existence. Most likely it was a carry over from JP-6 which was developed for the Valkyrie (Air Force). Pratt had already been working on the engine for a Navy program as well. As far as the elastomers, I can't comment because I can't find anything that lists what they were.

Every piece of the aircraft had to be one made, true, but the techniques were not completely different from what already existed. I am sure the forming and welding of Ti at the time was a complete *****. However, all of those processes existed. They new they had to figure out new ways to do things, but at least they had the building blocks already in place. If that wasn't the case, could they have possibly rolled out the first A-12 in some insane time frame like 2 years? You can't even begin to think about how to make something until you know the materials you can use. We can't say anything like that for carbon nanotubes.

Can you name those small incremental improvements? My understanding is that this is not the case (though I could be wrong).

Well, considering our space program started back in WWII with all of the German rocket scientists we divied up with the Russians when we won the war, one could say that development started there. Those people developed the Atlas rockets which powered the Mercury program which undoubtedly tought a lot of lessons for the Gemini program which then fed into the Apollo program and the Saturn V. Look at the listing of what was done on each flight of the associated program. Each flight had a new thing to try and then got built upon.

 

[mugaliens]

It will most likely happen, not in ours or my kids' lifetimes though.

Sweeping statements like this are never true (said tongue in cheek...)

Seriously, in the 30's, these ideas were laughed at as futuristic nonsense. Thirty years later...

 

[FredGarvin]

I'd be more than willing to bet money on that sweeping statement if there was any way my descendants could collect on it.

 

[DaveC426913]

Seriously, in the 30's, these ideas were laughed at as futuristic nonsense. Thirty years later...

It would be nice however, to avoid the world war driving the advancements .

 

[Pattonias]

Wow, this is the most negative look at the space elevator I have ever seen. In theory the only thing limiting the development of the space elevator is materials tech. Do you really think that given enough time we won't develop a material strong enough?

To say that it will never happen is ludicrous. All it tells me is you won't be the ones developing the tech and I don't have a problem with that. To say that it is science fiction isn't any more of a detraction, cell phones used to be science fiction also.

I am a fan of the space elevator idea and I will continue to be. If you have a better idea for getting materials into space for tiny fraction of the current cost than by all means help to develop it. Right now this one is nearly within our reach. Carbon nano-tubes are less than a decade away from being strong enough right now at the current rate of research!

And to compare this tech and fusion to nonsense is ridiculous. We are building a experimental http://www.iter.org/default.aspx" reactor in France.

If it wasn't for people doing research in these seemingly far-fetched fields we wouldn't have any of the technology we have today. None of it.

And for those who want to hear about the "space elevator" from a credible source take your pick, there are over 2,000 hits on the NASA http://search.nasa.gov/search/search.jsp?nasaInclude=space+elevator" .

 

[mgb_phys]

The main problem for the space elevator is that it's an all-or-nothing
You can't, unlike aircraft, spaceflight, or any other engineering, build up gradually.

So even assuming you had a material that could do it, it's still a bit tricky.

 

[LURCH]

I just don't see any credible way of getting around the problem of sattelites in LEO.

 

[Cyrus]

Wow, this is the most negative look at the space elevator I have ever seen. In theory the only thing limiting the development of the space elevator is materials tech. Do you really think that given enough time we won't develop a material strong enough?...

If anything, you have to admire his enthusiasm.

 

[LURCH]

Wow, this is the most negative look at the space elevator I have ever seen. In theory the only thing limiting the development of the space elevator is materials tech. Do you really think that given enough time we won't develop a material strong enough?

I have no doubt that a strong enough material will be developed. However, for a space elevator to be possible around the earth, we would have to first eliminate all of the sattelites in low Earth orbit. There is no point on the equator over which these sattelites will not eventually pass. When they do, they will strike the elevator shaft at about 15,000 miles per hour. If we hadn't done sattelites first, a space elevator would be possible. But as far as I have seen, no one has ever addressed this situation adequately. And, as the situation currently stands, a space elevator is simply not possible.

 

[DaveC426913]

I have no doubt that a strong enough material will be developed. However, for a space elevator to be possible around the earth, we would have to first eliminate all of the sattelites in low Earth orbit. There is no point on the equator over which these sattelites will not eventually pass. When they do, they will strike the elevator shaft at about 15,000 miles per hour. If we hadn't done sattelites first, a space elevator would be possible. But as far as I have seen, no one has ever addressed this situation adequately. And, as the situation currently stands, a space elevator is simply not possible.

This is an area of lively study. The cable is heap big flexible and can be maneuvered. Simulations have been done that show the cable can be moved out of the way of any satellites. (Don't assume that it is as simplistic as I describe. There's a lot more to it.)

 

[dr dodge]

IMHO, It'll never happen.
for gosh sakes, we can't even agree on putting up wind towers without some group pitching a hissy fit about "issues"
I have real problems with all current nano tech. there ia a lot of it going on, but very little health and safety understanding. nano fibers pass right thru most living tissue. now, string a massive amount of it together, hang it in the air, subject it to intense light, heat, wind and radiation and tell me it won't sluff nano particles into the air.
another thing that no one has addressed is the electrical charge that it would pick up. anyone remember the shuttle experiment with dragging the cable?
http://istp.gsfc.nasa.gov/earthmag/wtether.htm
from what I heard, they almost blew the whole electrical system due to the massive emf ramp up
think on big long carbon resistor.
how many golfers and fishermen get hit by lightning thru their carbon graphite accessories?
that thing would probably drag lightning in on an unbelievable scale.
spend the $$$ on the aircraft industry, with their proven track record of slow, but positively forward advancement
best bang for the buck and absolutely the safest

dr

 

[DaveC426913]

spend the $$$ on the aircraft industry, with their proven track record of slow, but positively forward advancement
best bang for the buck and absolutely the safest

Other than the VentureStar, what is the aircraft industry's solution to achieving orbit?

The industry's delta vee is shy by a factor of 10. (2,500mph vs. 25,000mph)

Space shuttle doesn't count; it's just a rocket.

 

[dr dodge]

all I was saying is that some technology that generally works well, exists in the aircraft/aerospace industry
its a lot closer than a 200 mile vertical cable, built out out of untried material by a technology that we don't have. (I like the nanobot idea best)

personally, I think its going to be real hard to beat the rockets for quite some time

dr

 

[DaveC426913]

all I was saying is that some technology that generally works well, exists in the aircraft/aerospace industry
its a lot closer than a 200 mile vertical cable, built out out of untried material by a technology that we don't have. (I like the nanobot idea best)

personally, I think its going to be real hard to beat the rockets for quite some time

dr

Rockets are rapidly reaching a point of diminishing returns. You don't see any more Saturns going up do you?

 

[dr dodge]

the rockets weren't/aren't good for heavy lift, and that's where the real need is.
but for most mid to small stuff they will probably be used for many years

dr

 

[chayced]

I don't really like the idea of a space elevator. Lots of technical challenges, lots of cost, in the end you have an untested expensive system that you put into some sort of geosynchronous orbit, and if it crashes down after a week you have nothing to show for it.

Why not focus on a space gun? We have the technology to launch projectiles into orbit, and having the majority of the propulsion system on the ground where it is easily repairable is a definite benefit. I guess the idea is just not trendy enough to be researched.

 

[LURCH]

I don't really like the idea of a space elevator. Lots of technical challenges, lots of cost, in the end you have an untested expensive system that you put into some sort of geosynchronous orbit, and if it crashes down after a week you have nothing to show for it.

Not true, not true! You have a huge, trench-shaped impact crater that goes almost all the way around the equator!

 

[Mech_Engineer]

Not true, not true! You have a huge, trench-shaped impact crater that goes almost all the way around the equator!

Like in the book https://www.amazon.com/dp/0553572393/?tag=pfamazon01-20!

 

[mgb_phys]

Why not focus on a space gun? ...I guess the idea is just not trendy enough to be researched.

It is researched.
the research goes something like:
V² = U² + 2as

Assume a 100m long barrel, and an escape velocity v of 11km/s
a = V²/2s = 11,000²/200 = 600,000m/s²
a = 62,000g
There is also the small matter of air resistance when the payload leaves the (presumably evacuated) barrel and enters the ground level atmosphere at > Mach30.

 

[mugaliens]

personally, I think its going to be real hard to beat the rockets for quite some time

Agreed.

Rockets are rapidly reaching a point of diminishing returns. You don't see any more Saturns going up do you?

Non-sequitor. While it's true that rockets are providing diminishing returns, that has nothing to do with the lack of current viability in the tether arena. Rockets are here and now. Tethers are several decades away, if not a century.

 

[LURCH]

Like in the book https://www.amazon.com/dp/0553572393/?tag=pfamazon01-20!

Please tell me they don't propose a space elevator on Mars?!

 

[mgb_phys]

Please tell me they don't propose a space elevator on Mars?!

It has certain advanatges, you don't have to wait for the butterflies

 

[chayced]

At this point putting a space elevator on Mars is the equivilent to putting a Starbucks there. When it does become possible it will probably be ancient technology.

 

[dr dodge]

ok, I have been thinking about this (I know, VERY dangerous)

Wouldn't surface tension of the gases of the Earth's atmosphere follow the cable higher up the cable. That could potentially cause odd plasma reactions when it got to space. transmitting power up it would require it to either be 2 cables next to each other, or some sort of induction/coax kind of deal. and it would have to be like trying to push massive megawatts thru a tera-ohm resistor.
OK, we make the cable, how are we supposed to get it to the earth. upper atmosphere winds would drag it around all over while we are trying to get it to the ground. think about lowering a piece of fishing line off your roof to touch a 1/4 inch square a basketball on the ground. even on a zero wind day, you'd have to send out so much extra cable just to finally get a grip on it to drag it back to the point of attachment. at the point in time that we were just ready to attach it to the earth, the static on that thing would be...well
How much slack would it need to allow for the wobble of the earth? The pulling on the cable would try to pull the satelite out of orbit on the way up, and shove it out on the way down. you'd need a spool of cable the size of the moon, and a tensioner the size of rhode island to keep the cable tension correct.
IMHO, the following formula applies:

elevator idea+(many$$$$$$$$)=stick and deceased equestrian

dr