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Comment by relix | Hacker News Reader

We don't need to solve the gravitation issue. People are spending long term time in the ISS and with proper training it's not bad.

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The long-term effects of zero or low gravity on human health are very serious - muscle, bone and eyesight loss and a host of other problems. Current mechanisms of dealing with the problem (exercise and special suits) do not cater adequately to long-term space journeys.

They're doing 6-12 month missions on the ISS these days, which would be roughly similar to a Mars transit.

The gravitational field in the low earth orbit is quite large compared to what you would encounter in outer space.

The ISS is at a distance less than 5% the distance between us and the moon.

isn't the problem weightlessness, not zero gravity?

ie, centrifugal acceleration canceling out low gravity in LEO

No, weight is just mass plus some sort of acceleration, if there's something to substitute gravity everything would be well, the main problem is with body fluids, we evolved to deal with earth surface level of gravity, in the interplanetary space I do not see how centrifugal acceleration is possible unless it's something that the spaceship do to generate it, from what I know this is hard and do not see solved in the foreseeable future. I would love to be wrong.

The gravitational field you're in doesn't matter if you're in free-fall.

You're probably right, I am not a physicist, but this is the only when you consider rigid bodies right?

Nope, this is actually just a restatement of one aspect of Einstein's Theory of General Relativity, which applies to everything.

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