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NASA Question, why is this a problem?

Brian

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B
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A CNN article reported this about space missions over 1 year long.

"NASA has tried to limit space stays to about six months because of health concerns. After extended periods in zero gravity, muscles atrophy and bones begin to degenerate."

Couldn't they just do exercises with rubber band resistance? Isometrics?
Or, am I missing something?

And why would bone be affected?
 
As far as I know, no one's quite sure yet why bone is affected (If someone is, I'd enjoy being enlightened)
That's the problem.
 
Well, the brain is used to the effects of gravity on the body, and has evolved feedback mechanisms based on the assumption that it's always going to be there. When you take it away, several things happen.

You have several groups of muscles, mostly in your legs and spine, that work against gravity to maintain your posture. In space these muscle groups are no longer of use and can atrophy at rates of up to 5% a week.

Bones atrophy for much the same reason - your brain senses the pressure on various bones and uses this as a guide for how strong they need to be. If this pressure disappears it no longer makes sense to keep the bones built up.

On Earth there is a significant blood pressure difference between your head and your feet - the latter can be as much as triple the former. In the absence of gravity it equalizes all over, and your brain interprets the increased intracranial pressure as an excess of blood, and reduces your blood volume. This reduces the workload on your heart and can cause it to atrophy as well.

Exercises can help, but for some reason gravity seems to be necessary to avoid atropy. There are some experimental exercise systems in design now that would give the illusion of gravity, perhaps via vacuum or rotation.

Of course, none of this matters if you plan to live in space for the rest of your life. ;)
 
I thought there was a plan to attach two spacecraft together, by means of a long cable (Or one spacecraft to a discarded booster or similar mass) and have them pirrouette around each other to create an artificial gravity. Has this plan been abandoned?
 
Cecil said:
This reduces the workload on your heart and can cause it to atrophy as well.
Click to expand...
ewwww.
Thanks for the info. That's interesting.
 
Your skeletal systems has these little cells that build up or remove calicium where ever it's needed most. It all depends on whet kind of activities you do. Thats one of the ways forensic specialists can deduce from bones what type of labor or activity a deceaced person once did. (i.e. a build up of bone in the areas of where a hevily used muscle was attached. Since the body is not under the same forces in space they are on earth. the cells remove calcium from the bones and dumps it in the bloodstream.
Bungy cords do not replicate the same forces on the bones as gravity does.
They need to develop something similar to the rotating wheel dealy like in 2001: A space odessy.
 
I recall an experiment described in National Geographic some time back in which poultry (and presumably humans as well) could be placed for a short time every day on a plate that either vibrated or sent electrical impulses through the feet and caused significant (20% or thereabouts) increase in bone density.

Haven't heard anything about it for a while though.
 
Cecil said:


Bones atrophy for much the same reason - your brain senses the pressure on various bones and uses this as a guide for how strong they need to be. If this pressure disappears it no longer makes sense to keep the bones built up.
Click to expand...


Wait a second.

Are we sure it's the brain doing this? Never heard that.

I don't think the brain is involved in bone density.

Isn't it much more likely that it's a physical process rather than a neurological one?


But yes, the human body does atrophy in space. If we can figure out why the bones do, it's possible we can devise a solution that doesn't require a ship that spins its way to mars.
 
the bones, I'm told, are made of a peizo electric material. so that when you step on it a small current is generated to , and I'm guessing here, provide a feedback loop of some sort.

combine this with what cecil said.


Virgil
 
And how does the brain work with this?


I'm serious. Just because there's electricity involved in osteogenesis doesn't mean the brain controls bone growth.
 
Silicon said:
And how does the brain work with this?


I'm serious. Just because there's electricity involved in osteogenesis doesn't mean the brain controls bone growth.
Click to expand...



I'm guessing the small electric current goes via the nuerons to the brain, maybe the thalumus and stimulates increased generation of bone formation, or decreases bone destruction.


I'm not an expert , just sharing what I know.

I know the body is a complex web feedback systems so...
Virgil
 
I'm quite sure that the electrical impulses, or vibrations whichever it was, were administered to the feet.

There was no way to administer it to the head, and the fragment of the caption in my memory holds the same.

If somebody could dig this up though, I'd really like to know how or if it works.
 
Virgil said:




I'm guessing the small electric current goes via the nuerons to the brain, maybe the thalumus and stimulates increased generation of bone formation, or decreases bone destruction.
Click to expand...

Now that makes some sense.


Cecil wrote:
your brain senses the pressure on various bones and uses this as a guide for how strong they need to be.
Click to expand...

And I took it that he was saying the brain was sending "growth" messages to individual bones.

That seems way strange.


But I'll ask it again, do we actually know that the brain is doing this? Or do bone cells grow in the lab when we exert pressure on them?
 
my guess is the electrical signal trigger chemical signals that regulate the competing processes of bone distruction and reformation.

your bones are constantly being broken down by the body while at the same time rebuilt.

so if there is a lack of rebuilding because of lack of gravity or excercise the bone destruction becomes more apparent.

the brain is in there somewhere. the thalumus and hypo thalumus etc... release chemicals which in turn cause the body to release chemicals etc...

it would be the old brain because this is seen in lower animals as well.

I really not an expert in this area, but this is what I've worked out as a related scientist and my reading.

studies I've read shows that excercise prevents bone loss in old people (stress on the bone)



Virgil
 
Alright!

I found the National Geographic I made reference to, it's the January 2001 edition. Huge article about the rigors of space upon the body.

The experiment with animals standing on plates was mentioned in conjunction with SUNY as Stony Brook, appearantly it's vibration, not electrical stimulations.

Anyone who has a stash of old Geographic can look it up now, if they care to. The whole article is actually quite interesting.
 
bewareofdogmas said:
They need to develop something similar to the rotating wheel dealy like in 2001: A space odessy.-uruk

Working on it http://www.oscarsamusements.com/rides/gravitron.jpg

Nanotech is also being worked on for fixing problems with the body; no giant bike wheel needed.
Click to expand...

Alas; if you calculate the tidal forces given the size of the 2001 wheel, you get values that suggest the astronauts would be puking much of the time.
 
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