It has been found that micro-gravity adversely affects blood flow to the human eye. How will this problem be treated on flights to Mars, for instance? Rotating spacecraft, perhaps?

  • $\begingroup$ Glasses, if any ... there are much severe affects on the human body muscular dystrophy, bone loss, psychological effects, etc. Basically it is assumed: Homo Sapience is able to handle it long enough for a trip to mars (and maybe back). $\endgroup$
    – CallMeTom
    Commented Jun 26, 2020 at 6:07
  • $\begingroup$ @CallMeTom Most of negative effects of microgravity have a serious impact only after return to full gravity, and don't impair 0-g operations. The eyesight deterioration is different than the rest in that it impairs astronauts while in space. $\endgroup$
    – SF.
    Commented Jun 30, 2020 at 15:04
  • $\begingroup$ Certain people have been on the ISS for more than a year, and a flight to (or from) Mars lasts half a year. So there's no urgent need to create artificial gravity on Mars flights, and Venus comes even closer. Another question is whether effects like eyesight deterioration would also occur in the lower gravity of Mars, but we simply dunno. $\endgroup$ Commented Jul 3, 2020 at 16:12
  • $\begingroup$ @LoveForChrist: Mars gravity is about 1/3 of Earth. We have a pretty good idea of impact of 0g on health and reasonable understanding about >1g but for anything in between 0 and 1 exclusive - the longest periods are of order of minutes. We absolutely don't know if 1/3g will be enough. $\endgroup$
    – SF.
    Commented Jul 7, 2020 at 12:26
  • $\begingroup$ @SF. Martian gravity is about 3.72 m/s² or about 0.38g which is far from "a third g" but otherwise you're right. One could test the effects of low gravity on the Moon or on a rotating space station generating 0.38g. $\endgroup$ Commented Jul 7, 2020 at 12:40

1 Answer 1


Rotating for now seems to be the only viable option for artificial gravity, and alternative is keeping a constant acceleration of g halfway through the journey, and reversing it to slow down with g on the other half, which unfortunately requires a lot of fuel.

And there are a lot of effects the different gravity has on the human body, which also won't end after the trip is done, since Mars' gravity is also smaller than Earth, there is no telling just how much our physiology would be affected in the long term!

For more on that see:

  • 2
    $\begingroup$ it's not known that a full g is required, but any constant acceleration is prohibitive. $\endgroup$
    – user20636
    Commented Jun 26, 2020 at 8:46
  • 4
    $\begingroup$ "Requires a lot of fuel" vastly understates the problem. It's totally intractable with any engine technology we can build in the foreseeable future. $\endgroup$
    – ikrase
    Commented Jun 26, 2020 at 9:41

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