SpaceXVision Renders Mars Spaceship With Rotating Gravity

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SpaceXVision has published renderings of a Mars Spaceship concept for an artificial gravity Mars/Earth cycler.

15 thoughts on “SpaceXVision Renders Mars Spaceship With Rotating Gravity”

  1. This’ll be an expensive failure. I strongly recommend that they test this on a very small scale before going all in. Centrifugal forces work differently in space with the absence of gravity. The RPMs necessary to produce a measurable sensation of gravity is immense. There are easier ways to do it that are both energy efficient and integrated as part of other ship systems, thereby making it simpler with fewer failures modes.

  2. Rotational gravity isn’t practical during the boost/breaking phase of flight. The thrust will be perpendicular to the centrifugal force of the rotating section.

  3. Once Mars base gets established these larger safer more comfortable transports will be needed. Leveraging Nuclear or some other more efficient propulsion. Will make transit safer more efficient and not require as many fuel launches or as many ships since huge numbers wont be making long travel journeys instead will just be back and forth shuttles on both sides. Makes efficient as launch shuttles bring in cargo fuel return with cargo back forth to heavy transport.

    Will also open up exploration out further in the solar system.

    • I didn’t initially pick up that this was supposed to be a cycler.

      But in order to match speeds with a cycler, you have to put yourself into a cycler trajectory, which is pretty close to just a regular transfer orbit. Where it saves you fuel is not in the delta-V requirement, which is unchanged, but in that your “taxi” at each end of the trip doesn’t have to be capable of keeping you alive in comfort for the whole trip. You can pack them in like sardines, and skimp on the life support.

      The cycler gives you spacious, radiation shielded accommodations for the trip. You just have to pile back into the Starship to land.

      The downside is that the cycler has a fairly poor duty cycle. One leg of the trip is fast, the other very slow, and only the Aldrin cycler manages to complete a trip every synodic period. So you’re looking at a ship that’s only useful for one trip in every 4-12 years, approximately.

      What’s illustrated is probably a “semi-cycler”, which uses propulsion to minimize necessary delta-v for the taxis. It really only gains you anything if you use a very high ISP propulsion system like nuclear.

  4. That’s crazy. You’d just pair up the starships after they set out, connect them with suitably long tethers, and spin that up. Structurally much, much simpler and economical, and it gets the job done just fine. Better, even: Your radius can be long enough there’s be no issues with motion sickness. The only thing it requires that the Starships wouldn’t already have is a kilometer or so of tether, and suitable points to attach it at.

    • It doesn’t even require two crew Starships, one could be cargo type and those will be plentiful and cheap. Mass could be balanced by propellant levels. It would also mean the crewed ships would have extra propellant and resources nearby.

    • I sincerely doubt that Emperor Musk I is going to arrive at his recently conquered domain via tether. He’s going to arrive in style.

      • In an early interview Musk was asked if he’d be on one of the first waves of manned ships to Mars. His reply was that he wanted to travel to Mars, not impact it. He’s sensibly realistic about how dangerous the early trips will be.

        So, we can reasonably expect that by the time he travels to Mars, it will be a later generation of Starship at the least, or perhaps via a cycler.

        But if you’re going to have gravity on the early trips, you’ll use two ships and a tether.

  7. Too massive for an interplanetary vehicle. A simple artificial gravity habitat consisting of three pressurized modules attached to two expandable booms would be substantially less massive. Water can be used for shielding against heavy nuclei and solar events that could be dumped just before the trajectory burn into a high Mars orbit.

  8. Wheels are a bad idea – high rpm that cause disorientation. Mass and surface area inefficient Better to have redundant long thin cables between two ships. Or alternatively a long ship that rotates end over end (ideal for nuclear propulsion with engine at one end, like Discovery 1 in 2001 movie).

    • A rotating wheel of the size shown, if generating Mars gravity, should be slow enough to not cause dizziness. Even if generating Earth gravity, it’ll be slow enough that most can easily adapt to it – around 3rpm.

      As to whether it’s too big – that depends on how many people it is to carry.

      Also – the main problem with two ships connected with cables would likely be instability, allowing rocking and axial spinning induced by shifts in on-board mass, which could also induce nausea and potentially injuries. Some sort of damping would definitely be required, ideally active damping to avoid allowing rocking to start.

      • I would expect that rather than one tether, which would indeed be subject to rocking and spinning around the tether, you’d have a minimum of three tethers, anchored to the perimeter of the starships. The anchors could incorporate damping mechanisms, to the extent necessary, but just supporting the load at distributed points alone would largely suppress most such oscillatory modes.

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