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  1. #1
    Join Date
    Feb 2013
    Wa. state

    Artificial gravity tether

    One of the health problems mentioned in the manned trip to mars is zero G. Has SpaceX thought about tethering ship noses together and spinning up 2+ ships to create a desired g force during the trip? How many rpm's vs circumference of rotation would be acceptable health wise. How long a tether in other words..... given the coriolis forces acting horizontally on passengers.
    Last edited by Grant Hatch; 2019-Aug-31 at 05:27 AM.

  2. #2
    Join Date
    Jul 2005
    No-one knows. We don't know how high a rotation rate is tolerable in the long term, or how high the gravity needs to be to maintain health,
    Conventional wisdom, dating from centrifuges in the 1960s, set a limit of 6rpm for Coriolis tolerance, giving a radius of gyration of 12-24m for 0.5-1g.
    But people can habituate to 10rpm, and at least some to 23rpm. See Clement et al. (2015) for a good review.
    Doubling the rotation rate lets you reduce the tether length by a factor of four, since force scales with rotational velocity squared and directly with radius. So these higher rotation rates would get us down to such short tethers that there would be a significant gravity gradient from head to foot.

    Robert Zubrin proposed such a tether system for Mars Direct, back in the 90s, so it's been out there for a long time.

    Grant Hutchison

  3. #3
    Join Date
    Jun 2007
    They've most likely looked at it, but it's not necessary for the ~4 month durations they're talking about for Mars transit.

  4. #4
    Join Date
    Jun 2003
    The gravity could be reduced to 0.3 on the outward trip, to acclimatise the astronauts to Martian gravity, then increased to 0.5 or more on the way back.

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