I don’t know what the current space flight record is, but I do know that extended stays in orbit are attended by bone decalcification and muscle loss. I think this can be offset with an exercise regime, but I don’t know if it can be completely offset. I don’t know if other medical problems arise in freefall, or are likely to arise even if they have not yet been observed. I also don’t know if some problems are temporary and merely reflect a transitional period during which the body is adjusting to new conditions.
As an added question, what would be the effects on a child if the entire pregnancy, from conception to birth, occured while the mother was in freefall?
Resistance training would be easily attained in freefall. Also, part of the problem with weightlessness, IIRC, is that the GI tract and other bodily functions rely a bit on gravity, which wouldn’t be a problem in freefall.
I suspect starvation might be an issue after a while.
People have lived on Mir for months at a time. I’m not aware of any of them starving.
Your entire digestive tract consists basically of tubes lined with muscles that push things along. It’s called peristalsis, and it’s why you can swallow even if you’re hanging upside down. It happens in your intestines as well. You don’t need gravity to push stuff along.
I have had people try to swallow while hanging upside down and it isn’t easy. With liquids it is impossible. The difference between this and weightlessness is the when you are upside down you are working against the force of gravity not in the absence of it.
With regards to other replies, certainly peristalsis is necesarry to push food along but I can’t believe that gravity doesn’t play a role at all. We’ve evolved on a planet with gravity. It’s no coincidence that the mouth is at the top and the anus at the bottom.
Well, I suppose the answer to that question would be “right up until you hit the ground” – because, as they say, no one ever died from falling … it’s the stopping at the end that kills you!
Training can counteract, to a certain extent, muscle loss. However bone decalcification is largely due to the lack of gravity at all times - when asleep, when at rest, when awake, etc. Supplements don’t work, as they just get pissed straight out again. A few years ago I heard there was some research into HRT-like treatment to allow astro/cosmo/tikonauts to retain calcium hormonally, but haven’t seen anything more about it, nor any results.
I don’t know the answer, I just wanted to say how happy I am to see someone correctly describe the condition of an astronaut in a space station as “freefall”.
Spiff and anyone else who is confused, just because you’re falling doesn’t mean you’ll ever hit the ground. The ISS, like anything in orbit, is always falling, and missing the Earth.
I take the responses so far to mean that nobody can think of any objection that’s both obvious and valid. (If eating were a problem, records would be on the order of days, not months, and even that would be pushing things.) So nobody can think of anything medically wrong with a group of people going into a space station in a stable orbit with a self-sustaning biosphere and living out their lives and having their children live out their lives and so on unto the millionth generation?
Even with exercise in space the astronauts who’ve returned to Earth after long periods of weightlessness have had trouble walking and needed time to build up their muscle mass. There’s been speculation that some of the bone loss experienced by them would be permament, but I don’t know if there’s been any studies to bear that out. A quick search of NASA’s site doesn’t turn up anything useful as far as animal studies go. I would think that they’d be able to stick an animal on ISS for a number of years to see if the bone loss would “bottom out” or if it’d continue until they were just “jello sacks.”
The secret of flight, remember, is throwing yourself at the ground and missing. This bears an uncanny resemblance to how every single manmade satellite avoids becoming extremely hot scrap metal (at least for a while). Compare flicking a rock off a table to getting an MLB pitcher to launch it at 100 mph at some other highly-paid yahoo’s glove. Both rocks traveled a parabolic path, but one rock’s path enabled it to miss the ground for longer. A satellite is, one, pushed up above most of the atmosphere so friction is much reduced, and, two, pushed forwards with much greater force, such that its parabolic path enables it to miss the ground long enough to circle the Earth completely and come back where it started.
Gravity still plays an intimiate role in its life, it just isn’t causing it to rain down upon your head. Without gravity, its path wouldn’t be a curve. It would be a straight line.
Now that you mention this, I do kind of recall hearing something about it. The lack of studies is quite disappointing and somewhat disconcerting. Certainly we have enough astronauts from the old Mir and Skylab days of long-term space flight we can do longitudinal studies.
This also reminds me of an old SF idea, that people could become so acclimated to freefall that they couldn’t successfully adapt to life at one gee.
So sorry. I considered the OP to mean freefall, as in jump from an airplane, or into a bottomless pit. Hence, wind rushing by allowing resistance training, and a lack of fall through windows in bottomless pits.
Believe it or not, I had read the very competent and informative posts that preceded mine. And I certainly recognized that they all focused on the type of freefall experienced by an astronaut in orbit.
I’m going to nitpick enormously and say that ‘parabolic path’ is not accurate in either case, though it’s a lot harder to see this in the case of the rocks than the satellite. (If the satellite followed a parabolic path it would have escape velocity and fly far, far away from the earth.)
In the case of the rocks, the deviations from parabolic path that make their trajectories ellipsoid are almost impossible to notice under normal earth-surface conditions. (If I remember correctly, the trajectory comes in as a true parabola if you model the earth’s surface as flat and ‘down’ as being a vector that is parallel with respect to all points. When you model the earth’s surface as spherical and ‘down’ as converging towards the center, then that makes the trajectories ellipsoidal.)
I’d be careful using words like “impossible.” I have seen more than one performer on TV drink thinks while standing on their head…full glasses of beer, etc, not just a sip or two that they could keep in their mouth.