Business, Economics, Space, Technology and Society

Tethers Unlimited

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Just had an interesting visit there, where they’re working on a lot of tech that will reduce (to the limited degree it exists) the justification for large-fairing launch payloads, with new orbital-assembly techniques, including 3-D printing. They’re working on (among other things) ways of building large lightweight trusses for orbital structure, that could lead ultimately to assembly hangars. They’re also developing ways to recycle a lot of plastic goods (like bubble wrap and zip locks) into cord to feed 3-D printers at the ISS. Very exciting stuff.

7 thoughts on “Tethers Unlimited”

  1. Rand,

    I’ve been a big fan of what Tethers Unlimited (and Made In Space) have been doing in the in-space 3D printing realm. Combine that with what DARPA was doing with satlets on their Phoenix program, and you have the underlying pieces for building large, upgradeable spacecraft.

    ~Jon

    1. Companies like TU and Altius remind me that the gold miners weren’t the ones who got rich in the California gold rush – Levi Strauss did.

  3. Great news, just in time for TEOTWAKI.

    Reading the news today, it looks like we’ve just missed the window for expanding our domain into space, and will be falling back into savagery any day now.

  4. A third technology coming along may magnify the results that Made In Space and Tethers Unlimited are working TOWaRDs. IT IS PRESENTLY BEING CALLED “NANO-ARCHITECTURED TRUSSES” BY A GROUP AT CALTECH INVOLVED WITH THE RESEARCH.

    http://jrgreer.caltech.edu/home.php

    THEY ARE MAKING TRUSSES OUT OF TRUSSES, WHICH ARE MADE OUT OF TRUSSES THEMSELVES. THE RESULTS OF THIS IS STRENGTH ON THE MACROSCALE AT THE SAME LEVELS AS SOLID MATERIALS, WHILE DOING IT WITH MASSES 100S OR 1,000S OF TIMES LESS. THIS HAPPENS NOT ONLY BECAUSE OF THE LEVERAGE AND STIFFNESS OF TRUSSES. IT ALSO HAPPENS BECAUSE THEY HAVE FOUND THAT WHEN TRUSS COMPONENTS ARE SMALLER THAN THE SMALLEST WEAKENING DEFECTS IN A GIVEN MATERIAL THE MATERIAL CAN MAINTAIN ITS FULL THEORETICAL STRENGTH. IMAGINE MADE IN SPACE BEING ABLE TO DELIVER TRUSS COMPONENTS TO SPIDERFAB that are as good as what they plan to use now, while having a mass 100 times lower.

    There is another tie in with spaceflight as well. The teams at Caltech, Los Alamos, and Livermore, are having trouble scaling up production of their smallest trusses, and it is because of gravity. TheY DESIGNATE IN 3-d their nanometer scale thickness components using what is called “two-photon lithography” in a vat, in which a liquid plastic holds material at the ready.

    Two laser beams produce a smaller spot in a beat frequency where they interfere than they can designate with either laser alone. This beat frequency is selected to catalyze the congealing of the clear plastic liquid into which the lasers shine. Once their truss is designated in congealed plastic, they lift it from the vat of plastic liquid, and use the plastic truss as a mold around which they cast the main truss in a strong material using CVD, or sputtering, or a number of other techniques. As I said, however, in Earth gravity, this production method does not scale well.

    In free fall, however, one should be able to start with the stronger material in particles smaller than the wavelengths of the lasers, floating in free fall. Each laser separately passes through the build volume, and their beat frequency is selected as the frequency best absorbed by the strong material. The beat frequency fuses the particles together directly. This should not only work, but scale up to production rates similar to what we hope for from 3d printing in the future.

    If that works, then not only will we produce trusses with 3-d printed components for spacecraft that can be 1/100th the mass of today’s spacecraft, but we would have products that can be made in Space, but not at all on Earth. Those could be brought down for use here at substantial profit.

    We then have a product that may make asteroid Iron and Nickel a salable item on Earth. Even before that is possible, we could make a profit even when we have to launch the raw materials into orbit from Earth. The return on each kilo brought back from elsewhere in the Solar System could go up many times.

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