Can Quiet, Efficient 'Space Elevators' Really Work?
By Leonard David, Space.com's Space Insider Columnist | February 19, 2014 06:38am ET
Posted on 02/22/2014 8:13:46 PM PST by ckilmer
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 An electric-powered climber spacecraft rides up the space elevator.Credit: Frank Chase/Chase Design Studios |
Is it time to push the "up" button on the space elevator?
A space elevator consisting of an Earth-anchored tether that extends 62,000 miles (100,000 kilometers) into space could eventually provide routine, safe, inexpensive and quiet access to orbit, some researchers say.
A new assessment of the concept has been pulled together titled "Space Elevators: An Assessment of the Technological Feasibility and the Way Forward." The study was conducted by a diverse collection of experts from around the world under the auspices of the International Academy of Astronautics (IAA). [Quiz: Sci-Fi vs. Real Technology]
The study's final judgment is twofold: A space elevator appears possible, with the understanding that risks must be mitigated through technological progress…and a space elevator infrastructure could indeed be built via a major international effort.
The tether serving as a space elevator would be used to economically place payloads and eventually people into space using electric vehicles called climbers that drive up and down the tether at train-like speeds. The rotation of the Earth would keep the tether taut and capable of supporting the climbers.
Rooted in history
The notion of a beanstalk-like space elevator is rooted in history.
Many point to the ahead-of-its-time "thought experiment" published in 1895 by Russian space pioneer Konstantin Tsiolkovsky. He suggested creation of a free-standing tower reaching from the surface of Earth to the height of geostationary orbit (GEO; 22,236 miles, or 35,786 km).
Reach for the sky. Image depicts key elements of a space elevator, from top to bottom.Over the last century or so, writers, scientists, engineers and others have helped finesse the practicality of the space elevator. And the new study marks a major development in the evolution of the idea, says IAA president Gopalan Madhavan Nair. [10 Sci-Fi Predictions That Came True]
"No doubt all the space agencies of the world will welcome such a definitive study that investigates new ways of transportation with major changes associated with inexpensive routine access to GEO and beyond," Nair writes in the new study's preface.
"There is no doubt that the Academy, due to this study, will contribute to advancing international consensus and awareness on the need to search and develop new ways of transportation in conducting space exploration while preserving our universe in the same way we are now trying to preserve our planet Earth," Nair adds.
Elevator operator
While it's always tricky to predict the future study lead editor Peter Swan told Space.com that space elevators are more than just a science-fiction fantasy. "The results of our study are encouraging," he said.
Swan's view is fortified by the late science fact/fiction soothsayer, Arthur C. Clarke, who stated in 2003: "The space elevator will be built ten years after they stop laughing…and they have stopped laughing!"
Swan is chief engineer at SouthWest Analytic Network, Inc. in Paradise Valley, Ariz., and is focused on developing and teaching innovative approaches to "new space" development. He's also head elevator operator of the International Space Elevator Consortium (ISEC), which has organizational members in the United States, Europe and Japan and individual members from around the world.
ISEC's goal is nothing short of getting a lengthy space elevator built.
"The question is when, of course," Swan said. "But the point is that the technologies are progressing in a positive manner, such that we who work in it believe that there will be space elevators."
Climber ascends space elevator, heading spaceward from its aeroshell.Pacing technologies
Swan said the giggle factor regarding space elevators is "down significantly" given work carried out over the last decade by a global network of individuals and groups. "Still, there are many, many issues and I certainly would not want to say that it's not a challenging project."
The IAA appraisal delves into a number of issues, such as: Why build a space elevator? Can it be done? How would all the elements fit together to create a system of systems? And what are the technical feasibilities of each major space elevator element
?
Two technologies are pacing the development of the space elevator, Swan said.
Producing an ultra-strong space tether and other space elevator components, Swan said, has been advanced by the invention of carbon nanotubes (CNTs) that are 1,000 times better in strength-to-weight ratio than steel. The good news, he said, is that CNTs are being developed with billions of dollars by nanotechnology, electronics, optics, and materials specialists.
Similarly, lightweight solar cells "are coming along nicely," Swan said. "That's an industry that the space elevator people are watching, too. We're not going to drive it, but we can certainly watch it and appreciate the advances."
Money, motivation and desire
Regarding who would erect a space elevator, Swan said the study dives into details. A primarily commercial effort with some government support is possible, as is a public-private enterprise, or an entirely governmental project.
"All three are viable. Any one of them could work. It's a matter of money, motivation and the desire to do it," Swan said, though the study centers on commercial development of the space elevator. "It's conceivable all three could be going on at the same time."
The study team was encouraged by the future, though Swan and others acknowledge there are many questions left to be studied. Indeed, another evaluation of the space elevator idea 10 years hence would be worthwhile, Swan said.
Erasing the rocket equation
Space elevator makes use of an ocean platform to connect Earth with space.Are there any technical, political or policy "showstoppers" that could prevent the space elevator from becoming a reality?
"You're asking the wrong guy," Swan responded. "I am an optimist. I have always had the attitude that good people, motivated by good rationale working hard will make it work. My guess is that space elevators are going to work, whether it's by 2035, 2060 or even 2100."
Swan said the rationale is moving beyond the "rocket equation," which involves tossing away 94 percent of a rocket's mass sitting on the launch pad.
"And it still costs a lot of stinking money to get up there," he said.
The space elevator opens everything up, Swan said. It's a soft ride, a week to GEO. There are no restrictions on the size or shape of payloads.
"People will laugh and ask why did we ever do space rockets…it's a dumb idea," Swan said. "Space elevators are the answer if we can make them work. Why would you do anything else?"
A copy of "Space Elevators: An Assessment of the Technological Feasibility and the Way Forward" is available through Virginia Edition Publishing Company at: www.virginiaedition.com/sciencedeck
The idea is to use cable made from carbon nanotubes or similar, yet-to-be-invented materials. These have a tensile strength by weight of about 100 times more than steel. So, in theory, a cable could support its own weight into space and also carry additional payload weight. The problem so far has been the ability to produce continuous lengths of such cable.
While there are many obstacles to be overcome, the feasibility is very likely at some point. Some of the questions here sound like people mocking the idea that a jet made of metal could ever fly — carrying its own weight as well as that of cargo and passengers. Of course we now know that it is feasible and also a profitable and worthwhile accomplishment.
Space elevator technology could allow space colonization in a way that is not currently feasible.
Was that the one with Tim Robbins? That WAS weird, but I liked it.
Your opinion utterly without any basis in fact
No. The biggest problems will be space junk, weather like the jet stream, low flying satellites are NOT geo-synchronous so this station will have them whipping by quite often
Back in the day, BC (before children) I spent some of my free time gaming. In 1997, when Voodoo cards were all the rage, along came a space “sim” that really had some great gameplay. The intro, however, was (at the time) pretty awesome; still kinda is.
If you look at this youtube clip of that intro and skip to 7:15 you’ll see the concept of a space elevator in action. If you get a chance, check it out.
http://www.youtube.com/watch?v=C9AN1hpbw2Y
would be massively heavy
If made out of carbon one foot in diameter, 18,193,470 tons. I suspect that carbon nanotube cable 1 foot in diameter couldn’t even come close to supporting 18 million tons plus other stresses.
...........
carbon nanotubes are extremely strong small and light.
IIRC, carbon nanotubes are hollow. Thus, a cable made up of them would not "weigh" as much as a solid length of either diamond or graphite. I don't know how big a cable would be necessary to support the load. Perhaps it would not need to be that large.
Also, the cable would weigh less as you ascended because of the centrifugal force acting on it. At geosynchronous altitude it would be "weightless." Above that altitude, it would actually pull "up" on the cable.
Your point may still be valid, but your calculation is not.
There is an awful lot of space in space. The odds of anything hitting such a relatively small cable would, I think, be slim. Not zero, but still slim.
Maybe.
Until that puppy snaps about 2200 miles up and the next thing you know, half of Poland is decapitated!
I’ve been around cables with high stress tension on them.
They can kill you so fast you won’t even realize you’re dead!
If I remember my meteorology correctly, hurricanes always form at least several degrees latitude north or south of the equator and never cross it (something to do with the Coriolis effect, I believe).
Since the elevator MUST be built on the equator, hurricanes should not be a problem.
ouch
An object at the equator is moving about 1050 miles per hour due to the rotation of the Earth. An object at geosynchronous orbit altitude must move at 3430 mph to be "weightless." Therefore, as you pull an object from the surface to geosynchronous altitude, you must accelerate it by 2380 mph to avoid pulling the cable like a bowstring.
I'm not sure if jet streams ever cross the equator, where the elevator MUST be built. I don't think they do, but I'll have to do some research to be sure.
tides for sure, but the fundamental problem is that there is an upper bound of strength for materials. Molecular bonds only have so much strength, and they just don't have enough. And before some genius out there says something about jet engines or bumblebees and thinks they've made some sort of point, consider the periodic table is well known as is the strength of molecular bonds
Tether Ball.
What prevents gravity from pulling the cable down to earth? It’s not like there’s going to be a hook at the end of it attached to the moon........
The giant at the top is not going to be pleased.
Space junk, de-orbiting satellites, meteorites, ect. This thing is stationary, everything in orbit is traveling thousands of miles per hour.
Then there is the problem of cutting across Earth’s magnetic field, turns out that pinholes in the material generate plasma and melt the material - see here:
http://www-istp.gsfc.nasa.gov/Education/wtether.html
I think this will have to wait until we master the manufacture of cosmic string ... www.andersoninstitute.com/cosmic-strings.html
sun, moisture, wind, airplanes....
Okay, let’s say we somehow get around all that. I’m just doing a little math here: Moving at 100 mph, It’s about a 26 day trip one-way, non-stop. A little over three weeks. Four if the speed drops to 90 mph. How much power is it going to take to a) lift something and b) keep it from falling at terminal velocity?
And I can just imagine humans on board with a breakdown happens. Not a crash, just a breakdown. How do you make repairs as say 200,000 feet?
And another thing: just for poops and laughs, I decided to check the weight on this pipe if it happens to be 1 inch carbon steel.
249,984 tons.
Yeah, I know, it would have to be a lot bigger than an inch.
So, can I go back to laughing now?
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