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This answer and the linked YouTube video discuss some difficulties with the experience of artificial "gravity" generated by small rotating craft (like one that could be launched to Mars in the near future). The gravity gradient from head to foot and especially the Coriolis effect would be quite strong for a small craft, and could conceivably be more uncomfortable than no gravity.

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note: One could use an external mass and tether for a more uniform artificial gravity, but that's a separate issue.

After a flight to Mars with no artificial gravity, what would the initial experience be like after landing? With no ground crew to assist, would the crew simply sit there for a while, then slowly start moving and assisting each other? Would robotic assistance be particularly helpful in this case? I can imagine without a ground crew, I'd appreciate some help from a robotic arm, bringing me things I ask for, helping me stand, and possibly get out of my bulky suit.

Would Mars' lower gravity compared to earth reduce the risk of breaking a bone (considering the bone loss associated with the trip) or would that still be a major concern?

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This is a prototype of the robotic arc welder that will tack-weld the F9 legs down after landing at sea. (humor) A similar device could assist the astronauts, but at lower voltage.

https://i.stack.imgur.com/GlGwI.jpg

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It's really difficult to say how this might be. At the very least, I'm confident that a Mars crew would have access to the same kind of equipment used on the ISS to help strengthen muscles. The trip to Mars is about 6 months. The gravity is significantly less than on Earth. Bottom line, I suspect that it might take a little time to adjust, but the 1/3rd gravity would be relatively easy to overcome after the 6 month stay. They no doubt would need to take it a bit easy for the first few days, but they would be quickly back into the swing of things. On Earth, it takes up to 3 weeks to get back to normal.

The bottom line is, we'll only really know once it's happened. It's impossible to simulate that level of gravity on Earth. And if we could create a Martian gravity in space, we'd just take that system to Mars.

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  • $\begingroup$ I think we're supposed to say 3/8 gravity now. :) I'm particularly interested in the first day or so. Will they sit in their Maximum Absorption Garment and drink from tubes, or stand up and de-suit and grab something from the galley? I've watched a number of ISS crews get out of their Soyuz and they really don't look like they could take care of themselves or each other that well. Scott Kelly's performance seems particularly animated compared to most of them, I don't think it's representative, but it's earth gravity. $\endgroup$
    – uhoh
    Jun 6, 2016 at 12:06
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    $\begingroup$ I can't imagine them not moving at some point in the first day, if nothing else, their decent stage will probably not have enough life support to keep them going that entire time... $\endgroup$
    – PearsonArtPhoto ♦
    Jun 6, 2016 at 12:44
  • $\begingroup$ aha! I was going to make a comment along the lines of "if they have enough LOX for propulsive landing, they should have a little extra to breath" but then I remembered Super Draco's use Hypergolics. $\endgroup$
    – uhoh
    Jun 7, 2016 at 4:08
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Honestly I don't see how can we provide you with a good answer. Most of it depends on many parameters (nutrition, training, ...) that are currently heavily researched by NASA and other space agencies. I guess the correct answer should be "We don't know yet, we're working on making it as negligible as possible". Also, how well the crew is trained during trip will depend on compromises too: diminished workload/leisure time, space needed for training machines, ...

However, considering the results of the latest NASA's twin study, you can expect that the crew will arrive in good shape, especially since mars gravity is lower than that of earth.

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  • $\begingroup$ I'm asking about the experience after landing, not crew health, so I don't think "negligible as possible" is actually addressing the question. $\endgroup$
    – uhoh
    Jun 6, 2016 at 8:27
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A journey to Mars would be about half a year long. That's as long as astronauts currently are staying on the ISS in their expeditions, in microgravity. So if Soyuz/Dragon/Shuttle astronauts can adjust to 1 g when returning to Earth, they will even better and faster adjust to 0.38 g. And, as mentioned in another answer, Scott Kelly (and other astronauts) were even longer in the weightlessness of space continuously. What's more tricky is how Martian astronauts would readapt to the Earth's gravity when returning from their 2-year-mission in which they were only in 0 or 0.38 g. But on this one can't give a reliable answer as yet. There was no 2-year-stay on the ISS as yet and such a stay might be risky to the astronaut.

Scott had a hard time to adjust back to the Earth's gravity, but that's 1 g and he was a year in microgravity. Therefore, in this case we should learn how the astronauts from the "usual" expeditions readapt to 1 g, who are on the ISS as long as a trip to or from Mars would last. I'll ask a question on that. My question on the re-adaptation to Earth's gravity here.

This question may deal with the SpaceX Starship while NASA's proposed Nautilus-X spacecraft would indeed create rotational gravity of up to 0.69 g.

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