Skeleton decay during long spaceflights

[Andy44]

The morality of it will be settled on a case-by-case basis. Humans living in harsh environments may find it immoral not to do it, since survival depends on it.

It's still creepy, though, since genetic engineering by its very nature involves individuals who have not been born or even conceived.

 

[willy88]

It won't be so much of a problem when people actually live in space... afterall, if it were me, I would have my useless, heavy, pointless, energy consuming, wasted-mass legs amputated. Upper body muscle/bone workouts are much more easily achieved with resistance machines and the right nutritional suppliments... For astronauts who want to actually get off the space ship, however, legs may be of some use...

Keep in mind that in freefall, feet could be used (to some extent) as 3rd and 4th hands.... something that I do occasionally in 1 g when I'm too lazy to bend down!

 

[Andy44]

Or you could do like Aeon Flux's fellow assassin Sithandra did in the movie and get your feet replaced with a newly-grown set of hands.

 

[JEL]

a human from Earth, Mars or Venus would not be able to live long-term in freefall, and genetically engineered jellypeople would not be able to survive on any of those planets.

I may not be genetically engineered (if so I'm not aware of it), but as a 'jelly-person' I am indeed surviving on planet earth


Although I was only thinking about skeleton-decay in terms of present-day flights/long term missions to the moon and Mars, or even more distant planets in this solar-system, the longer-term issues of human survival are also very interesting.
Maybe we will eventually become like octopuss' with brains? Then we could live on earth and maybe on the moon europa, and probably in zero-G also.

Anyway, I read that 438 days is the current record for longest stay in micro-gravity by a current living human that was able to transition back to healthy life in 1G.

However, a base on either the moon or on Mars would probably require a human to spend several years in a below-1G environment (1000+ days probably), and this might still have some kind of lasting unwanted influence on human physiology (thinking that maybe there is some 'break-even' period for how long it is possible to live in zero-G before it becomes dangerous to return to a 1G environment again)

If people degrade past such a 'break-even' point, by a 2-3 year mission to Mars, then returning them to earth could be a real problem. Maybe even impossible.
A base on the moon might be less of a problem, if crew-shifting could take place every year of half-year (atleast the 438 day record would imply so)

Ofcourse if it is just the length of a flight, to either the moon or Mars, then there is no huge problem since a centrifuge, or maybe some kind of swing or other gravity-making contraption, could probably be built on the planet much more easily than off a planet.

Something like this maybe:

 

[tblaxland]

Anyway, I read that 438 days is the current record for longest stay in micro-gravity by a current living human that was able to transition back to healthy life in 1G.

Long duration crew members have lots of people around to help them with that transition. Imagine arriving at Mars after nine months and finding that you cannot perform the functions required in a critical situation shortly after landing...

 

[Sky Captain]

Is there any technical reason why artificial gravity is difficult to achieve? For example an interplanetary ship with a heavy propulsion module at one end and habitat module at other end with long spar section (needed anyway to put some distance between crew area and nuclear reactor) between could be spun end over end to generate artificial gravity. It would only require some extra fuel for RCS. No need for dedicated centrifuge that can break down and likely would weigh more than RCS fuel to spin up and spin down.

 

[Tex]

Spinning end-over-end makes sense to me. Mass that would be otherwise useless in the cruise phase is now producing gravity, instead of having a completely different system taking up weight and space.

I think the Orion pulse propulsion spacecraft were designed to spin end-over-end to mimic gravity.

Forgive my ignorance here, but it just seems like over a long flight during the entire cruise stage with this thing spinning end over end it would alter the course of the spacecraft a bit? I suppose if it did, it would be so little a mid course correction burn would be enough to fix it?

 

[T.Neo]

Forgive my ignorance here, but it just seems like over a long flight during the entire cruise stage with this thing spinning end over end it would alter the course of the spacecraft a bit? I suppose if it did, it would be so little a mid course correction burn would be enough to fix it?

I don't see how spinning the spacecraft would alter the trajectory, aside from minor alterations perhaps from radiation pressure or slight miscalculations during the spin-up burn, but I may be wrong.

 

[tblaxland]

Forgive my ignorance here, but it just seems like over a long flight during the entire cruise stage with this thing spinning end over end it would alter the course of the spacecraft a bit? I suppose if it did, it would be so little a mid course correction burn would be enough to fix it?

The effect would be so small to be immeasurable. The only way such a thing would occur is through tidal effects. Consider the Earth-Moon system. Tidal effects between the two are causing the Moon to slow the rotation of the Earth. The kinetic energy that is removed from Earth gets added to the Moon's orbit, causing it to increase in size slightly. The effect is very small (about 38mm/year) and only measurable in the long-term since shorter period perturbations are more dominant. Also consider that this effect only occurs because the mass of the Moon is so high compared to the Earth. On a spacecraft, any unscheduled water dump your did would dominate, by far.

 

[JEL]

Long duration crew members have lots of people around to help them with that transition. Imagine arriving at Mars after nine months and finding that you cannot perform the functions required in a critical situation shortly after landing...

Yes... excellent point.

I just read this:

about 80 percent of the astronauts who are in space for extended periods of time suffer dizziness or even fainting spells when they return to Earth, lasting several weeks after re-entry.

Link: http://www.amarsodyssey.com/2007/11/01/fainting-astronauts-base-of-new-study/

And fainting would obviously not be a very safe way to start a Mars mission

No such problems were encountered during the moon-landings though, as far as I know, so a moon-base should be safe and possible with what we now know about human physiology from the ISS and Mir missions, and the travel-times involved in going back and forth to the moon and earth.

 

[Andy44]

The Apollo missions only lasted a few days.

Getting to Mars, even with a fancy nuclear-powered VASIMR, means at least about a month and a half in freefall, much more with conventional engines.

Enough that without artificial gravity along the way, you won't be able to get out of your seat after you land on Mars.

 

[jedidia]

But we are talking about living in space/freefall aren't we? That to me means living your life there, not just a 6 month sojourn to our nearest neighbour.

Well, if you are talking about LIVING in space, especially being born in space, you open another can of worms. Agreed, someone who spends his whole live in space and never touches the surface of a planet would not need artificial gravity. But someone bred and born outside a magnetosphere similiar to earth would have some SERIOUS medical trouble even if he were not bothered by gravity. We'd have to find a solution for that too...