17 thoughts on “Nautilus X”

  1. Perhaps [Elon] will someday pick up the Nautilus ball which NASA dropped?

    It’s good to see NASA thinking along these lines but it’s over done. A BA330 has life support for six and could be put in LEO on a Falcon Heavy for a total cost of $200m to $250m. The upper stage of the FH becomes it’s engine (for almost zero additional cost.) Just add fuel tanks and fuel and you’re ready to go. This could happen in two years. Tether two together and you have artificial gravity and redundancy. Dragon landers complete the vehicle.

    Why not be so bold? It doesn’t have to be NASA or SpaceX. NASA just has to announce a willingness to buy passenger tickets for a mission and some businessman can take up the challenge.

    Solar powered ion drives might not be a bad idea either.

    1. Tethers for artificial gravity don’t work. It was tried in Gemini and made for a very uncomfortable ride — even without people moving around in the vehicle. You need a solid structure, not a bungee cord.

      Don’t forget about the science payload, too. If you’re transporting colonists, a Bigelow module might be all you need but if it’s an exploration mission, you’re going to want telescopes, manipulators, EVA equipment, etc.

      1. Ok then…

        …use a beam rather than a tether (or combination.) Thanks for the Gemini 11 ref. I hadn’t known about that. Gemini really was an amazing program.

        …include a science module as well. I agree you will want these. This means more fuel tanks but doesn’t change the time line much but would probably double to triple the cost (which is dominated by fuel to LEO.)

      2. Tethers for artificial gravity don’t work. It was tried in Gemini and made for a very uncomfortable ride — even without people moving around in the vehicle. You need a solid structure, not a bungee cord.

        You’re ruling out an obvious technology on a single data point? How about we try it more than once with a damping mechanism to reduce the obvious problem and then decide. It’s worth noting that people often work and sleep in environments that move around, such as ships and airplanes. So no, I don’t see that we need a solid structure (which incidentally, is typically not all that solid).

        But otherwise, thanks for the reference. I hadn’t known that Gemini had done that. Makes you wonder what NASA could have done by now, if they were serious about space development and related areas.

        1. While tethers are a simple solution, they introduce new failure modes and make some routine things more complicated. For example, it’ll be harder to perform routine course corrections with a tethered system. You’ll need to add dampeners to smooth things out such as people moving around. Not only can tethers themselves break, so can the retraction/deployment systems.

          1. That’s true as well for a rotating wheel section. It adds failure modes and it’s a gyroscope which may introduce other complications.

            Tethers have a number of advantages. It’s less complex (but can have redundancy for safety.) It allows for less complex/costly ships. The entire ship gets gravity rather than just a section so there’s no need to keep a schedule of where you stay in the ship. The length can be made long enough that the rotation is less. I suspect it’s workable.

            If the tether has problems you still have two perfectly good ships. Depending on what breaks on your rotating wheel you may lose your atmosphere and have no second ship for safety. I would assume you’d have enough fuel to correct for a broken tether (not prepared to do the math just yet… call me a coward.)

          2. Recent research suggests rotation rate is less of a problem than was believed in the past.

            Another problem with a tether is that it becomes quite difficult to transfer crew or supplies between the two ships. Connecting the ships with a pressurized tunnel would make life much simpler.

          1. Really?
            When the Tacoma Narrows Bridge collapsed they didn’t conclude that suspension bridges weren’t stable enough and go back to steel arch, what they did is look at what went wrong and design better. Using the Gemini 11 experiment as a reason to dismiss artificial gravity from tethers as impractical is nuts.

  2. Definitely use some sort of beam system, perhaps three+ of the tensegrity unfolding structures the Navy once tested for radar masts. Include increments of ISRU equipment with each group.

    The costs for transit could drop nicely, however, once you have a Phobos mine that gets you Oxygen and methane from carbonaceous material and water. Accelerate to Mars transit velocity, decelerate to Phobos orbit, fill up with propellant and send the lander to the settlement site, along with a propellant generator. Then send the cruise modules home to L1, where they are met by a new Dragon lander with crew, and more propellant. Not luxury by any means, but usable, and as facilities build up, cheaper with every trip.

  3. Any design will have failure modes. That’s a given. The apparent simplicity of a rotating tethered system is attractive. However, it also introduces some complexities that frequently get glossed over. For example, performing routine course correction maneuvers is a lot more complicated with a rotating flexible system. Before entering orbit at your destination, you’d probably need to stop the rotation and retract the tether. If that fails for any reason, you’d likely lose the mission.

    If the tether breaks while the vehicle is rotating, both ends will have a lot of inertia and angular momentum to overcome. You’d need to design propulstion systems into each end piece.

      1. Maybe three propulsion systems. You’d want your science platform to be as isolated from vibration as possible–putting it at the center would make a fair amount of sense. Your tether system would be lighter if you could off-load a bunch of the mass, so maybe you put most of your fuel at the center as well, in which case if you have a high Isp drive it’d make sense to put that at the center.

        The rotating components would need rockets for the spin-up/spin-down anyway; if the tether broke they could use the rockets to maneuver back to the center section and finish the trip under no g.

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