Scientists envision inflatable alternative to tethered space elevator

Scientists envision inflatable alternative to tethered space elevator

Summary: An inflatable free standing tower could one day carry equipment and tourists 20 kilometers above Earth, and it could be completed much sooner than a cable-based space elevator, say researchers at York University in Toronto, Canada.They envision a giant tower assembled with a series of modules made up of Kevlar-polyethylene composite tubes that would be made rigid by inflating them with a lightweight gas such as hydrogen or helium.

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An inflatable free standing tower could one day carry equipment and tourists 20 kilometers above Earth, and it could be completed much sooner than a cable-based space elevator, say researchers at York University in Toronto, Canada.

They envision a giant tower assembled with a series of modules made up of Kevlar-polyethylene composite tubes that would be made rigid by inflating them with a lightweight gas such as hydrogen or helium. This would actively stabilize the giant tower and allow for flexibility. The elevator would support a series of platforms or pods that would launch payloads into Earth orbit.

”You can visualize it as a system of nesting segments that roll out vertically and snap into position, much like a telescoping wand,” Seth said in a news article. “You’re not constructing externally, but rather, from internally.”

To test the idea, the team built a 7-meter scale model made up of six modules (see image below).

A 7-meter-tall demo/prototype tower stands in a stairwell (Credit: Thoth Technology Inc.)

A 7-meter-tall demo/prototype tower stands in a stairwell (Credit: Thoth Technology Inc.)

According to a post in New Scientist, the demonstration model consists of modules built out of three laminated polyethylene tubes 8 centimeters in diameter, mounted around circular spacers and inflated with air. The 20-kilometer version (15 kilometers tower atop a 5 kilometer mountain) would be made up of 100 modules, and would weigh 800,000 metric tons when pressurized.

The full scale structure would also require gyroscopes and active stabilization systems in each module to help it stay upright and withstand winds which could be coming from any number of directions simultaneously across the vertical span of the tower.

The team led by Brendan Quine came up with the idea while investigating an alternative to the use of rockets to get payloads into space but that would also overcame the technological challenges of envisaged space elevators based on tethers (image).

The problems with a space tether include material strength constraints, the need for in-space construction, the fabrication of a cable at least 50,000 km in length, and the aging and meteorite-damage effects associated with a thin tether or cable in Low Earth Orbit. Not to mention the envisaged use of ribbons woven from super strong nanotubes, which is a material that is as yet non-existent. The York inflatable tower, on the other hand, would use materials that are already available.

The team has filed for international patent protection for their design, in partnership with space technology company, Thoth Technology Inc. They hope to realize the dream of a space elevator with the next decade.

A paper (paid access req.) detailing the design, was recently published in the journal Acta Astronautica Volume 65, Issues 3-4, August-September 2009, Pages 365-375; it is co-authored by George Zhu, Assistant Professor of Space Engineering, and graduate student Raj Seth. it discusses the stability and control of the structure, methods for construction and its utility for space launch and other applications.

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14 comments
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  • Doesn't sound very sturdy

    I wouldn't trust my life to 15km long inflatable tubes
    although I do love The Fountains of Paradise
    zmud
  • RE: Scientists envision inflatable alternative to tethered space elevator

    Why not use the best of both? Build a buoyant tower up to intercept the space elevator coming down.
    This would also prevent the hazards of nanomaterial crashing to earth in the event of a failure as the tethered section would spin out into space and the tower would simply float away if it was broken up.
    cedley1969
  • RE: Scientists envision inflatable alternative to tethered space elevator

    This is an American web page, can the "kilometer" crap! Ir at least give your readers a conversion. When this country learns to convert to metric, then ok. 20 Km is 12.42mile., quite a feat, but still far off from what is needed to haul payloads to space.Write about this when the find something useful!
    winddrift03
    • We almost went metric :(

      Thank Reagan, and those who come to conclusions about what's correct on the basis of how it makes them feel, for the fact that Americans still use a primitive measurement system. Those of us who love science are ashamed of that fact.
      Americans handicapped themselves by refusing to learn a simple system. We undermined our manufacturing exports with the requirement that other nations buy extra tools and we crashed satellites.
      rp518
    • Metric...

      Science uses the metric system and I think most readers
      here are intelligent enough to know that. They also
      know that 1 mile=1.6 km.
      prof123
  • hydrogen?

    1. hydrogen is "slippery" and can easily leak (ask NASA about that one)

    2. a pressurized structure full of explosive hydrogen would be a terrorist's dream

    3. it has been said a rich person such as Bill Gates could privately fund the construction of a space elevator made from off-the-shelf materials. The only thing NASA would need to do is to go get an asteroid which would be used as an anchor whose mass would be in geostationary orbit 22,500 miles above the base.

    Terry Thomas
    Atlanta, Georgia USA
    AtlantaTerry
  • 7 meter segment isn't carrying a load...

    If it's to be used as an elevator, there should be workings for an elevator in that segment.

    I'm with those who don't see this standing up to the stresses it would be subject to. The sheer surface area to weight ratio, when combined with several miles of crisscrossing wind currents (including the JET STREAM for goodness-sakes!), as well as maintenance of cubic-miles of plastic and leaky flammable gas, combine to tell me this is not a very practical solution to the problem of cheap access to space.
    D. W. Bierbaum
  • 20 kilometers is only 12 miles!

    That doesn't exactly get you to orbit! Comparing this to a space tether is like comparing a pitchers mound to Mount Everest.
    jejamcl
    • It's barely more than 2X the height of Everest

      The Mount Everest analogy is a good one. But a direct comparison to Everest tells you even more. Everest is 29000 ft, i.e. 8.8km, this space elevator isn't much more than 2X the height of Everest. Another way to look at this is to compare it to the X15 which reached 108km, 5 times the altitude of this elevator.
      bjrosen
      • Could it launch something else?

        It takes a lot of energy to get to 20km, and that could help a lot. But we'd need a vertical launch from there. That's still a lot mass to lift to there and the elevator would not fare very well in the blast.
        rp518
  • But, it doesn't really get you into space. 20KM is nothing (NT)

    .
    goingbust
  • The problem is not just the HEIGHT, but the speed as well

    The problem here is that in order to actually get anything into orbit, you need to get something up to escape velocity. Just hoisting something up 20km into the air is not going to help. How are you going to get the object to speed up to [b]25,000 mph[/b]? A slingshot?
    Qbt
    • Advantages

      1. Greatly reduced atmospheric drag at 20km

      2. 20km of potential energy is nothing to sneeze at

      I'll bet that if you do the math, you'll find that this idea greatly reduces launch cost.
      dmclean9
  • Great stuff

    This is so cool. but I suggest a larger size supported by a small temperature differential it would preclude a terrorist attack on the structure. the hight is not as significant a problem as some assume a ladder type tethered structure outside the atmosphere can "rotate" the loads to higher orbit as well as loads to the surface. The atmosphere is the resistance that must be overcome in traveling to orbit. This is very good but I suspect it can be vastly improved upon! What about not attaching this thing to the surface to begin with? How about multiple structures free to circulate about the planet in the wind? There is much more to consider.
    Altotus