Inflatable Space Elevator Sparks Lofty Ideas - InformationWeek

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Inflatable Space Elevator Sparks Lofty Ideas

A new patent has been granted for a space elevator that will reach 12 miles high, and it might be the closest we've come to a working design.

NASA's New Horizons Brings Pluto Into Focus
NASA's New Horizons Brings Pluto Into Focus
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The second coolest elevator concept, behind Willie Wonka's glass elevator, is the space elevator. But for the most part, we're no closer to a space elevator than we were when the idea was proposed by Konstantin Tsiolkovsky in 1895. That is, until last month when the US patent office granted a patent to Thoth Technology for creating an inflatable space elevator.

For those unfamiliar with the space elevator concept, let me explain. Rockets are extremely hard to launch off the face of the earth because of gravity and air resistance. The space elevator looks to overcome that by attaching a vehicle to a tether of one kind or another so a vehicle can climb the tether into space. It is a slower, less violent (no controlled explosions) way of getting into space.

There are now three basic kinds of space elevator concepts.

The original concept required taking a long wire into space with a counterweight on the end and attaching the other end to the equator. The natural spin of the Earth would keep the wire rigid, like when you swing something at the end of a string here on Earth. More recent concepts have involved building a slightly more rigid structure, possibly out of carbon nanotubes. In fact, a Japanese company claims it will do this by 2050, and it will extend a quarter of the way to the moon.

There are also plans that involve erecting what amounts to a large building that isn't that much different from what we build today. To do that, however, we need major breakthroughs in materials and building techniques. Here is a very pretty NASA animation done in 2000 of what a rigid space elevator would look like.

The most recent concept designed by Thoth is slightly less ambitious, but it uses technology that, for the most part, we already have (to build the building at least). It uses modular tubes of Kevlar-polyethylene composites filled with helium. The tubes are much lighter and forgiving than modern building materials, and the helium helps hold the structure up. Building it would look something like this:

OK, it would look nothing like that, but those little puppets are awesome. Here's a video of a bunch of them dancing to Taylor Swift.

Anyway, the Thoth elevator would reach about 12 miles into the air, still inside Earth's atmosphere, but high enough up that it would be much easier for spacecraft to enter space. Building a structure that is 12 miles high is hard enough. We don't really need to try building one that leaves the Earth for space. Thoth envisions using rockets, like those SpaceX is developing, that can land on a barge, servicing the International Space Station and other missions from a platform at the top of the elevator. It could save considerably on fuel and make missions much safer, because the lowered gravity would mean rockets could take off using a single-stage motor. The designer compared it with the ease of a 747 taking off.

Of course, you've got questions like, what happens if a 12-mile-tall building falls down? Good question. The answer is that things definitely won't go well. It would need to be built in a fairly remote place, but it is rather unlikely that the building would suffer a total catastrophic failure. Its modular tube design would allow for the other tubes to hold up until repairs could be made. These types of tubes are already used in space and are fairly reliable. In the event of a collapse, it would be far less damaging than a building made with current construction techniques.

(Image: Thoth Technology)

One estimate is that when fully built, the elevator would weigh 880,000 tons. By point of comparison, the Empire State Building weighs 365,000 tons. It takes 45 Empire State Buildings to reach the height of the Thoth Space Elevator. That's about 20 times heavier. And I don't even want to think about what happens when a Space elevator that stretches a quarter of the way to moon fails and gravity brings it back to earth like a rubber band snapping. Or, worse, a rigid building falling from space. So of the building material options, this seems by far the safest.

Another concern is cost. The goal of a space elevator is to reduce the cost of space travel from $20,000 per ton to some more manageable number. The Japanese plan says they can reduce it to $200.

[ Cost battles have been fought and lost for a long time. Read Space X, Hubble, Coffee: The Cost of Doing Business in Space. ]

One questions the ability of a giant building to reduce costs when, for instance, I'm not sure the global helium industry would even be prepared to handle it.

Let's say just for fun that it could. The current market price of helium, is $75 per cubic foot. Assuming the elevator is 14 miles tall and has the same dimensions as the Space X landing barge (that's what they hope lands on it) it will be 300 feet by 100 feet at the top. By my calculations, the cost of the helium to fill it would be more than $14 billion. That's the cost of six Mars Curiosity Rover missions. Even assuming  a bulk discount, we're talking a lot of high profile space missions before it pays for itself.

And that's not counting the cost of maintaining or repairing a building 12 miles up in the air.

There's another, more terrestrial, problem. The Space Elevator needs an Earth Elevator. Somehow, you've got to get people and materials to the top of the thing. At 12 miles, you're higher than commercial airplanes fly and much higher than helicopters fly, so everything that launches from the platform at the top has to come from an elevator on the ground.

One of the fastest elevators in the world is in the new One World Trade Center. It goes about 23 mph. That means an elevator going that speed would take over an hour to go up and then come down to take its next trip. Try taking rockets that can weigh 1 million pounds assembled, and moving the parts a few thousand pounds at a time on trips that take an hour to go up and back. And then try assembling all of that 12 miles high.

In other words we need bigger and faster elevators before we ever build a space elevator. And they need to be light enough and rigid enough to move up this thing without bringing it down. The advantage to the cable style space elevator is that its rigidity comes from the spin of the earth. The rigidity of the Thoth Elevator is in its own structure, and it has to fight gravity.

If it sounds like I'm saying this won't work, I'm not. I'm saying we've got some really big problems to overcome. Until Thoth or someone else is granted a patent for a very fast elevator that won't threaten to pull down a helium structure, we won't be building this anytime soon.

Still, it is an incredible idea and one that I think is still more feasible than the carbon nanotube string to the moon. Right now, we can make carbon nanotube chains that are as long as 3 centimeters. Only 59,652 miles to go. I'd convert that into centimeters for you, but I don’t have space for that many zeroes. Let's call it 1.4 trillion to round it off.

In other words, both technologies will require some major engineering breakthroughs. Those breakthroughs are worth investing in, not only for space travel, but for other advancements on Earth. Perhaps the faster elevator will lead to faster Earth transport. Maybe something like Elon Musk's hyperloop could be perfected first as the option for moving materials inside a space elevator. Maybe whatever new elevator is built becomes the next subway system for your town. Maybe before we build a 12-mile-tall inflatable building, we learn to build inflatable apartments that are quick to erect, inexpensive, and safe to live in even in earthquake zones.

The point is the engineering problems have "real-world" applications. So it is problem worth solving. And Thoth has the inside track on solving it first. What do you think? Will you ever ride a space elevator as part of a trip to space? Tell me in the comments section below.

David has been writing on business and technology for over 10 years and was most recently Managing Editor at Enterpriseefficiency.com. Before that he was an Assistant Editor at MIT Sloan Management Review, where he covered a wide range of business topics including IT, ... View Full Bio

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JeffM012
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JeffM012,
User Rank: Apprentice
9/8/2015 | 3:24:34 PM
Nice overview, couple items ...
Like the article.  Although I think this "patent" is mainly a publicity stunt it has spurred is a nice discussion of how the costs of space elevators are very high and can't support a realistic business model.  

One item, in the article you re-state: "It could save considerably on fuel and make missions much safer, because the lowered gravity would mean rockets could take off using a single-stage motor."  I expect that 12 km up the gravity would still be over 99% of surface gravity, not much of a savings there.  I think the main fuel savings (which is only a few % of mission cost anyway) would be due to lower atmospheric drag due to high altitude on the rocket at "liftoff".  If you could save 20-30% of fuel you would have a lighter vehicle which could also save a few %, but if you are only using reusable single stage it will still be huge (larger than a traditional upper stage).  

Instead if you want to achieve this lower drag goal you would be better off with a 12 mile high 8-10m diameter cylinder with a partial vacuum.  Maybe this would cost 2-3 billion $.  If you created 12 km atmospheric density at the ground you might use a combination of rocket lift and rail gun (you would need a guide in any case) to essentially shoot it out the top at perhaps 1 km/s, then slowly turn horizontal in the orbital plane of your choice for the big burn to get you to 7.7 km/s + horizontal velocity.  Still it seemed like a lot of overhead to save maybe of 5% of mission cost vs landing the main stage.  It would take 100s of these lift offs to break even (vs the 1000s off  this inflatable space elevator).  

So, the reusable stages are by far the best bet for lowered cost with realistic system investments, redundancy and resilience.  

BTW, you can patent crazy ideas, the USPTO will take your money and fees, but a patent does not mean it a good idea, most patents are never used except for resumes, marketing, fund raising.
mreynoldsh
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mreynoldsh,
User Rank: Apprentice
8/14/2015 | 12:52:49 PM
not sure about this...
"we're no closer to a space elevator than we were when the idea was proposed by Konstantin Tsiolkovsky in 1895."

this is not particularly accurate. in 1895 the strongest cables were 1895 steel wire. in 2015, i can purchase industrial quantities of sk-90 polyethylene fiber rope, which is 15x stronger by weight than the current best steel cable. this is sufficient to construct a working space elevator on the moon. increasing material strength by one additional order of magnitude gets us close to a space elevator off the earth. my opinion is that the original tethered cable elevator concept will be the one that gets built, and if we maintain a reasonably stable political/economic world i think it will be designed and under construction by 2050 if not sooner. It seems to be the only practical way to get people and resources back and forth to the rest of the universe. 

 
soozyg
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soozyg,
User Rank: Ninja
8/9/2015 | 12:36:09 PM
Re: the money
@AllyV132 I understand your point, and I suppose I am ignorant to the situation, only thinking of the present time. It just seems like not just a fortune, but an absolute deluge of money and time that would have to go into planning/designing/buildng something like this. No country, government entity or even private citizen has the money or could create the infrastructure to fulfill it and I'm not sure how it could be organized. I guess it will happen way past my lifetime so my opinion is moot.
Li Tan
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Li Tan,
User Rank: Ninja
8/8/2015 | 9:11:07 PM
Re: Thanks for stirring up the Crackpots.
I doubt if this is really feasible. 12miles is really big number. Nowadays human have built buildings as high as 800 meters or so and there are already bunch of problems to solve. This is still less than 1/12 of the space elevator we discussed here. Maybe in the near future it will become realistic but at this moment it may not be feasible from engineering perspective.
seminone
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seminone,
User Rank: Apprentice
8/8/2015 | 9:01:36 PM
Re: Thanks for stirring up the Crackpots.
Hello Ally;

 

You are quite correct about the importance of density in relation to buoyancy but you are making a few mistakes and I quote you;

 

"the key question is not the total mass of the structure but the density of the structure compared to the density of the buoyant volume"

 

Unlike a SpaceShaft, (or otherwise known as an Atmospherically Buoyant Spar Platform Space Elevator,) a tower, like a building, has to stand on foundations or on a surface, hence it is not buoyant. You can have a very low density cylindrical structure filled with He (even with each of the building blocks somehow separated,) but it all will be just weight. Moreover, a very tall cylindrical section of the tower (or upright airbeam) will be proportionally less buoyant than a sphere of the same diameter. Let me explain.

 

Imagine an equatorial line on a balloon. This line will indicate the divide of the atmospheric weight above the balloon while below the equatorial line it will be the atmospheric buoyancy. If you now consider a buoyant tube with the same diameter as the balloon the flat surface areas at the top and the bottom of the tube will determine its buoyancy. Hence, the higher the top surface is to be, the lesser the atmospheric weight acting on the top area and this will directly influence the buoyancy at the bottom surface of the tube. And, when comparing both the balloon's equator and the tube's wall the atmospheric environment acting on both surfaces is nothing else but pressure, no weight or buoyancy. These top and bottom areas determine mainly the buoyant efficiency and "not" other factors such as density, viscosity, etc.. Furthermore, as you rightly indicated, it will also be necessary to take into account the weight of the structural section(s) to have the net value of buoyancy. So such buoyancy condition cannot exist with a tower but only with a SpaceShaft.

 

In the case of a SpaceShaft the design of the structure is such that it takes advantage of what we call cumulated buoyancy. On its own, this subject merits quite a bit of pen-and-paper so I will later, on a different posting, provide a directions to how to get a paper explaining the mechanism.

 

Regarding your indication to the necessary velocity to achieve orbital flight. This is indeed the real problem. However, this problem is not insurmountable either. My apologies because I will again use non mathematical descriptions to illustrate the solution.

 

Energetically speaking, any rocket system used for orbital missions consists of a vertical and a horizontal components. The vertical component consist of gravity and atmospheric drag opposing the thrust. While for the horizontal component; drag is negligible, especially at 20 km and above. In the case of any rocket system intended to access Space, the first stage is meant to take both "vertically" the second stage and the payload up to an altitude at which there is no atmospheric drag to affect the second stage flight. The fact is that, despite its colossal size, a first stage rocket never achieves supersonic speed. All it does is contribute a very small horizontal component of less than 300 km/hr to the second stage. And it is only after separation that the much smaller second stage takes over as to achieve escape velocity. And these all has to happen just between about 20 km of altitude and typically the Karman Line, at 100 km of altitude. However, most often, first stage (or boosters) separations happen at 20 km or below.

 

Therefore, what the real problem is for achieving the necessary (almost instantaneous) tangential speed. Unfortunately, there is "no will" to develop such engines by any private company. Not even SpaceX wants to do this (or the others) despite the losses with their really crazy idea of vertically landing a first stage rocket.
AllyV132
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AllyV132,
User Rank: Apprentice
8/8/2015 | 7:40:05 PM
Re: the money
"is it really worth it"

Amerlia Earhart and Frederick Noonan took off from Lae, New Guinea in 1937 to complete a mission costing over 100,000 dollars; a fortune at the time. It served no purpose. It brought no water to children. It carried no mail. It changed nothing.

Or did it? Thanks to the efforts of people like this it heralded a new age of aviation that has saved countless lives, from Ebola victims to Hurricane victims. It allowed organs to be transported from a donor in New York to a recipient in Los Angeles. It provided the power to hurl you through the air at 500 mph across the continent.


The kind of thinking behind comments like that is, with all due respet, backward and ignorant. But that is not intended as an insult, for it is human nature to think only in the present. But I would simply suggest that a general rule of thumb is that the quest to fly higher, faster and farther has evidenced an incredibly reliable pattern of progress for humanity.
AllyV132
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AllyV132,
User Rank: Apprentice
8/8/2015 | 7:27:06 PM
Re: Thanks for stirring up the Crackpots.
I doubt it. The acceleration required to reach orbital velocity would crush any cargo you wanted to send up. It would have a very narrow range of uses.
AllyV132
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AllyV132,
User Rank: Apprentice
8/8/2015 | 7:03:25 PM
Re: the money
"I understand that science is important and the exploration is important"

This is an oft-repeated urban legend based on 1960's thinking. Space flight today and in the future won't be about "science" field trips and "exploration". It will be about matter and energy, which has everything to do with "water for children".
WilliamB29901
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WilliamB29901,
User Rank: Apprentice
8/8/2015 | 3:22:15 PM
Re: the money
Throughout history, one type of social investment has proven its value over and over again, Transportation.
  • Horses & carts,
  • Babylonian boats,
  • Roman roads, 
  • Dutch traders, 
  • River barges, 
  • Railroads,
  • Interstate highways,
  • Aircraft,
  • The Internet,

Transportation has always improved the quality of life at both ends of the route.

As I mentioned, this inflated platform by Thoth is just a scam, but other means of reducing the cost of lifting mass off the Earth may prove to open a new low cost destination and ultimately save Mankind from extinction by creating new independent ecosystems.

Human exploration of space, at the moment, is absurd, but robotic industrialization of the Moon does not need to be expensive, and could easily pay for itself.

Remember, our economy is synergistic and nonlinear. Investing in the science and technology necessary to robotically build radio telescopes on the farside of the Moon could easily reinvigorate our economy and help prevent continuing wealth inequality, much like investing in the CCC did 80 years ago.
Gary_EL
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Gary_EL,
User Rank: Ninja
8/8/2015 | 3:10:19 PM
Re: Thanks for stirring up the Crackpots.
With all due respect, from earth to space. A rail gun uses electromagnetic force to accelerate either a projectile or a package. The military is getting ready to unveil it as a weapon. Perhaps in the future, it will be able to send up CO2, soil, water and plant seed up into space for growing food. In the nearer term, it might be used for bulk items useful for other space-based purposes.
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