According to this Wikipedia article, Starship will take on average 115 days (3.8 months) to get to Mars and 150 days maximum (4.9 months).

with an average trip time to Mars of approximately 115 days (for the nine synodic periods occurring between 2020 and 2037).

And according to this NASA article, an astronaut in one month in orbit loses the same amount of bone mass as an elderly women does in one year. Furthermore, a few months in space leads to an increased risk of bone fractures when load is applied to their bodies. And surely colonists on Mars will be doing a lot of physical work.

Although healthy astronauts did not develop osteoporosis during their four- to six-month stays on the space station, the levels of bone loss documented were still enough to raise the concern for an increased risk for fracture when astronauts’ skeletons are subjected to applied loads with working, lifting or falling.

After astronauts return from the ISS, they feel dizzy and nauseous. So the passengers of Starship will feel the same way returning to an environment with 1/3 of Earth's gravity after a 4 month journey in micro-gravity. This is a passage from this article.

Even after a ten-to-fourteen-day mission to space, the return is dramatic. Your balance system is turned upside down, and you feel very dizzy. When you stand up for the first time, you feel about five times heavier than you expect. All of this can be unsettling, and nausea is not unusual.

Of course they are returning to Earth which has stronger gravity than Mars but the side-effects are the same nonetheless.

Even with exercise, micro-gravity is a big concern that leads to many health problems and the fact that their are 100 people on-board makes it an even bigger concern.

So my question: How will SpaceX accommodate its passengers from the harmful effects of micro-gravity?

Side Note: I don't expect a proper answer with professional citations, any source where Elon Musk or the SpaceX team bring up this topic is sufficient.

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    $\begingroup$ There are really only two answers - rotation, or oughing it out and allowing a fairly lengthy period after landing to adjust. Two Starships attached tail to tail is one way to tackle this. $\endgroup$ Commented Jul 24, 2019 at 22:53
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    $\begingroup$ Why not exercise? That's what the ISS crews do. $\endgroup$ Commented Jul 25, 2019 at 1:05
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    $\begingroup$ @OrganicMarble Even with exercise, the effects of micro-gravity is still very harmful. $\endgroup$
    – Star Man
    Commented Jul 25, 2019 at 14:04
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    $\begingroup$ It's my understanding that the 100 passengers are for a intercontinental ballistic flight, and that missions to Mars will have much of that space taken up by supplies, life support, etc., so will have fewer than 100 passengers. $\endgroup$
    – Ghedipunk
    Commented Sep 24, 2019 at 23:58
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    $\begingroup$ An authoritative answer from SpaceX may have to wait until the mainstream press badgers them into doing so. The question has been floated for years. (And even then, the answer will change six times before launch.) $\endgroup$ Commented Sep 29, 2019 at 23:05

3 Answers 3


How will Starship ... accommodate micro-gravity?

As of today, it won't.

Making non-micro gravity by spinning about its long axis is impractical because the ship's radius is only 15 feet.

Others have made detailed calculations for spinning about other axes. This is the kind of thing that helps SpaceX cultivate its bonkers-but-works reputation, but SpaceX hasn't exploited it.

SpaceX's press kits mention topics like exercise and bone density and microgravity only in the context of experiments on ISS, which Dragon visits to resupply. So they're aware of the issue, but they're not yet announcing anything. No word about how to stow a dozen NordicTracks into three cubic feet.

They might not announce anything until they hire someone in that field. None of SpaceX's hundreds of job offers cover this topic. The closest they come is Radiation Effects Engineer (whoops, the effects on avionics, not on humans) and Environmental Health & Safety Technician (whoops, OSHA compliance for work sites, not in-flight).

But here's what is needed, from the literature.

To avoid bone loss, its occupants will need mechanical shock loading during exercise. This 1998 Acta Astronautica article reports:

... By applying an external impulsive load for a short period each day, which is intended to mimic the heel strike transient, to the lower limb of an astronaut during a long term space flight (5 months), this study tests the hypothesis that the bone cells can be activated by an appropriate external mechanical stimulus to maintain bone mass throughout prolonged periods of weightlessness.

... During the EUROMIR95 mission, an astronaut used this device for a short period daily [on only one heel]. ... Bone mineral density was maintained [on that heel], while it was reduced by up to 7% on the [other one].

To maintain muscle, exercise suffices.

We don't yet know how to avoid dizziness and nausea upon leaving microgravity.


A partial answer: according to Garret Erin Reisman, professor of astronautical engineering and former SpaceX human spaceflight developer, the current state of knowledge is that you can get around a loss of bone mass almost entirely by proper exercise.

The key to this is that bone loss is basically an issue of a lack of stimulation, and not a lack of exercise per se. So, the state of the art is to exercise with high intensity and low repetitiveness. Then, bone loss is very low, even in microgravity.

He said that almost literally at some point during the linked Space Show. Sorry I don't have the exact time at hand atm.

  • $\begingroup$ Also former shuttle astronaut. $\endgroup$ Commented Oct 2, 2019 at 11:12
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    $\begingroup$ It's worth mentioning that bone loss is only one (important) factor in long-term microgravity. We can expect that astronauts will experience significant difficulty with proprioception from head to torso after the flight, akin to what we see here: youtu.be/LIgMXGAGTgM. Reacclimation time is probably weeks. $\endgroup$ Commented Aug 3, 2021 at 16:18

Spacex does not know it is going to do that. It actually is delaying a crewed Mars landing for NASA and will soon be for Spacex.``

Source: The biggest lingering questions about SpaceX's Mars colonization plans


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    $\begingroup$ I had to downvote you because your source is almost 5 years making it totally inapplicable, and your point is inaccurate and speculative. NASA has no schedule or plans for any Mars landings because as yet it has no launch systems or interplanetary vessels capable of delivering humans to the surface and back. The answer to bone density loss is exercise, which has been proven to work well on ISS. $\endgroup$ Commented Apr 24, 2021 at 23:49

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