Mini-Throughput: Tumbling Chinese Rocket Edition

Michael Siegel

Michael Siegel is an astronomer living in Pennsylvania. He is on Twitter, blogs at his own site, and has written a novel.

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28 Responses

  1. fillyjonk
    Ignored
    says:

    I am old enough to remember Skylab and being worried about it as a kid.

    I guess the bigger worry about ‘space junk’ is if you’re an astronaut – lots of stuff floating around out there now. But still, it seems like better planning could prevent even the VERY remote possibility that someone might have their car flattened by a chunk of this thingReport

  2. Jaybird
    Ignored
    says:

    Remember this story? Back in 2007, China blew up a satellite.

    It was one of their own satellites so it wasn’t an act of war or anything.

    I figured that it was just a display of “HEY LOOK AT WHAT WE CAN DO!” as a way of saying “knock it off” to all of the countries flying satellites over China and taking pictures.

    But look at that last sentence of the story:
    But this single event probably doubled the number of pieces of space junk at its altitude range.

    I’m told that it’s possible to destroy a satellite in a less junky manner. Like, if the missile hit it from the other side, all of the debris would have been nudged to fall (however slowly) towards the earth. The way it was done just doubled the pieces of space junk.

    All that to say: China has long treated debris as a tomorrow problem instead of a today one.Report

    • Michael Siegel in reply to Jaybird
      Ignored
      says:

      I actually mentioned that in the first draft of the post but decided to focus more narrowly on rocket stages. But yeah that was kinda evil of them.Report

    • Oscar Gordon in reply to Jaybird
      Ignored
      says:

      I want to take out that satellite, but I don’t want to be seen as doing so deliberately, so instead, I will take out this satellite, which is junk, or something I own, and I will do so such that the resulting debris cloud intercepts that satellite.

      Obviously, such a tactic is no guarantee (orbital mechanics are both deceptively simple and devilishly tricky), but I wouldn’t be surprised to see someone try that.Report

      • Jaybird in reply to Oscar Gordon
        Ignored
        says:

        The Air Force had a commercial about this!

        I think that the plausible deniability would be attainable but I don’t know that it’d work against a fairly robust system that does stuff like keep track of space junk.

        Like, you could do this against a barely first-world country that only barely got a satellite up there, but I can’t imagine this working against, say, a Comcast satellite.Report

        • Oscar Gordon in reply to Jaybird
          Ignored
          says:

          Unless the satellite can alter it’s orbit, it’ll take out the Comcast satellite (assuming the debris field was on track). Comcast may find a way to sue you for the cost…Report

          • Jaybird in reply to Oscar Gordon
            Ignored
            says:

            Now I’m googling types of orbits.

            I’m pretty sure the geostationary ones can alter their orbits (they aren’t stationary as much as doing a figure 8 all day, every day) and it’s the ones in LEO or MEO that just orbit around over and over and over again.

            And LEO/MEO orbits strike me as being a lot more likely to be poorly modeled in the computer than modeled well enough to set up that chain reaction.

            But, hey. China did figure out how to hit something the size of a refrigerator with a missile. Maybe they’d be able to line up one hell of a billiards shot.Report

            • Oscar Gordon in reply to Jaybird
              Ignored
              says:

              Geostationary is far enough out no is going to ‘accidentally’ plug one.

              Altering an orbit requires reaction mass. Most satellites have some. They use up some doing final positioning, and keep a bit in reserve for emergencies and station keeping, but it’s not a lot. A lot of satellites ‘die’ not because of failure, but because they ran out of reaction mass and can no longer perform station keeping (orientation is often done with flywheels that are spun up or down to turn a satellite, and if a flywheel spins too far down, reaction mass can be spent to spin it back up).

              Dodging a debris cloud could force a satellite to expend too much reaction mass, and it either can no longer return to station, thus killing it by making it useless, or it so drastically shortens is useful life that it is effectively dead, unless it can be refueled.

              I’m not up on the latest satellite designs, but as it gets cheaper to send mass to orbit, I would not be surprised to see satellites designed with a refueling capability.Report

            • Michael Cain in reply to Jaybird
              Ignored
              says:

              I believe current end-of-life planning for satellites in geostationary orbit is to carry enough propellant that they can reposition into a higher orbit, opening up their slot. Geostationary orbit slots are a relatively scarce commodity.Report

  3. Oscar Gordon
    Ignored
    says:

    I’ve done work on 2-stage designs, that necessarily have very large stages, and you can design things such that the stage breaks up when discarded, or you have the stage end lower down in the atmosphere. But such decisions involves costs and trade-offs and clearly China just don’t care.

    If Karma has any say, and debris large enough should land in China.Report

    • Michael Siegel in reply to Oscar Gordon
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      says:

      Yeah, this is more your area of expertise so glad you weighed in. Feel free to write a post if you have additional insights!Report

      • Oscar Gordon in reply to Michael Siegel
        Ignored
        says:

        Nothing worth writing a post about. China can’t copy the Falcon 9 yet, so they can’t recover the 1st stage like SpaceX does. Putting self-destruct devices on rockets is a great way to get rockets that perform unscheduled self-destruction, and rockets are prone to that already.

        Stages separate according to the launch trajectory, so you can’t just ask them to separate lower in the atmosphere, since that involves re-working the trajectory, and possibly re-designing the rocket itself.

        What you can do it ask that stages over a certain size have separation links so the stage breaks into smaller pieces. It adds additional structure (& thus weight, and cost, and forces one to re-work the rocket equation), but we know how to do it quite well.

        China just didn’t want to, and felt that rolling the dice on re-entry debris was acceptable.

        And honestly, the odds are in their favor.Report

    • North in reply to Oscar Gordon
      Ignored
      says:

      If karma has any say the debris will land somewhere outside of China that is both fragile and belongs to someone influential, big and noisy. If it lands in China then it will “not have landed in China” or “Landed harmlessly just as was intended *Chinese national anthem plays*” regardless of what damage it actually did.

      No. What China would hate is if it, say, landed on a major Saudi oil refinery or depot and wrecked it, or if it blew through a sensitive American piece of infrastructure or flattened the EU parliament building (mmm actually that might help China’s image in the EU). Obviously it would be even worse, geopolitically if people died from it landing but I wouldn’t wish that on anyone.Report

  4. Oscar Gordon
    Ignored
    says:

    Off topic, I saw this yesterday. It’s a floating wind turbine. It sits on 3 buoys, so it’s mounted on a tripod, in a leaning configuration, so the turbine blades hang off one side.

    Advantages: More stable than a single pillar. The supports can be smaller, and more aerodynamic, which allows for the blades to be a follower orientation (the nacelle points upwind of the blades), so when the blades bend from the force of the wind, you don’t have to worry about blade tips striking the supports. That, coupled with the tripod design, means you can anchor it at the upwind point of the tripod and just let the whole thing weathervane with the wind, saving costs on expensive wind-following technology. And anchors are cheaper than sea floor foundations.

    Cons: You gotta keep an eye on the anchor and power cable, make sure excessive weathervaning doesn’t twist them beyond what they can take. Heavy seas are also a concern.

    It’s an interesting approach to the problems of offshore wind power.Report

  5. Kazzy
    Ignored
    says:

    Something like 2/3 of the Earth is ocean, right? Plus some other percentage which is non-ocean water. Then you have uninhabited areas. Taken together, what percentage of Earth could be considered uninhabitated? Not just like, there’s no houses there but like, there ain’t even a real chance of people there. I’d call parks and farmland inhabitated.Report

  6. Oscar Gordon
    Ignored
    says:

    Speaking of rockets, I can haz jetpack pleez?
    https://www.youtube.com/watch?v=suHOLFhbwsMReport

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