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artificial gravity a different idea...maybe?



 
 
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  #11  
Old August 20th 03, 11:49 PM
Roger Stokes
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Default artificial gravity a different idea...maybe?


"Karl Hallowell" wrote in message
om... Hi Folks
The real reason for artificial gravity is that there are serious
health consequences to living in a zero-gee environment for
any length of time.


What are these health consequences? What is the g threshold or range over
which they occur? What are the timescales over which they occur? (I'm
thinking of it in terms of possible asteroid colonies, or where asteroid
industrial facilities would require a number of resident technicians etc.)

  #12  
Old August 21st 03, 02:01 AM
Manfred Bartz
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Default artificial gravity a different idea...maybe?

"Roger Stokes" writes:

"Karl Hallowell" wrote in message
om... Hi Folks
The real reason for artificial gravity is that there are serious
health consequences to living in a zero-gee environment for
any length of time.


What are these health consequences?


Loss of muscle mass and reduction of bone density among other effects.
http://astrobiology.arc.nasa.gov/news/expandnews.cfm?id=988

What is the g threshold or range over which they occur?


No-one knows. Nobody has ever lived at 0.5G. There may not be a
threshold, it may be a proportional effect. There have never been
animal experiments in the range between 0 and 1G simply because we
don't have a centrifuge (yet) in orbit.

What are the timescales over which they occur? (I'm thinking of it
in terms of possible asteroid colonies, or where asteroid industrial
facilities would require a number of resident technicians etc.)


Zero G is not a problem for short durations, say a week or two.
Beyond that it becomes an increasing problem. As you can see from
reports about the condition of astronauts returning after extended
stays in zero G, they need a few weeks to recover to the point where
they function normally again. Regaining the original bone density
takes much longer (years).

--
Manfred Bartz

  #13  
Old August 21st 03, 04:52 AM
Christopher M. Jones
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Default artificial gravity a different idea...maybe?

"Roger Stokes" wrote:
"Karl Hallowell" wrote in message
om... Hi Folks
The real reason for artificial gravity is that there are serious
health consequences to living in a zero-gee environment for
any length of time.


What are these health consequences?


Loss of bone and muscle density (the bone density loss is the
real nasty one, think osteoporosis).


What is the g threshold or range over
which they occur?


We don't know. All we know is that they don't happen at 1 g
and they do happen in micro-g. What happens in the range in
between is just speculation.


What are the timescales over which they occur?


Duration of only a few weeks don't seem to cause major
problems, several months seems to be where things start
getting bad,. Currently we haven't studied durations
longer than about a year, but indications are that it
just keeps getting worse (bone loss continues).


(I'm
thinking of it in terms of possible asteroid colonies, or where asteroid
industrial facilities would require a number of resident technicians etc.)


The problem doesn't seem to be so much being able to live,
but in transitioning back to 1 g, where strong bones and
muscles are needed. If you live most of your life in zero-g,
indications seem to be that you'd be just fine.

  #15  
Old August 21st 03, 07:28 AM
Theodore W. Hall
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Default artificial gravity a different idea...maybe?

Zoltan Szakaly wrote:

The health consequences could be avoided by putting a load on the
body, for example using bunge cords to pull the shoulders to the feet.
This is similar to the treadmill they have that they run on.


Yes, and it has not been effective against bone loss. The load isn't
enough in either intensity or duration.

It has been suggested that shorter, more intense, strength-training
exercises might be more effective for maintaining bone structure --
more effective than the lengthy aerobic workouts on treadmills and
rowing machines that they do now. On the other hand, they need the
aerobic exercise to maintain their cardiovascular systems.

--

Ted Hall
  #16  
Old August 21st 03, 07:40 AM
Theodore W. Hall
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Default artificial gravity a different idea...maybe?

"Karl Hallowell" wrote in message
om...

The real reason for artificial gravity is that there are serious
health consequences to living in a zero-gee environment for
any length of time.



Roger Stokes wrote:

What are these health consequences? What is the g threshold or range over
which they occur? What are the timescales over which they occur?



Here's a summary:

http://www0.arch.cuhk.edu.hk/~hall/a...tation/2_1.htm

--

Ted Hall
  #17  
Old August 21st 03, 03:15 PM
Christopher
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Default artificial gravity a different idea...maybe?

On Wed, 20 Aug 2003 16:17:58 -0400, Lex Spoon
wrote:

(Zoltan Szakaly) writes:

You would just need permenant magnets embedded in the boots. The real
reason for artificial gravity is that there are serious health
consequences to living in a zero-gee environment for any length of
time. Plus, it helps keep your stuff sorted.


Karl Hallowell


The health consequences could be avoided by putting a load on the
body, for example using bunge cords to pull the shoulders to the feet.


Are you sure about this? Have there been any studies on these lines?
I could certainly see this helping with skeletal issues, but is the
skeleton the only thing that dislikes long-term zero-gee ?


The entire human body doesn't like long term zero g.


Christopher
+++++++++++++++++++++++++
"Kites rise highest against
the wind - not with it."
Winston Churchill
  #18  
Old August 21st 03, 11:11 PM
Andrew Gray
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Default artificial gravity a different idea...maybe?

In article , Gordon D. Pusch wrote:

Possibly the little detail that the "cylindrical surface" needs to be
about a =MILE= in diameter to get the rotation rate down below 1 rpm @ 1 gee,
since if it rotates faster than 1 rpm, the majority of human beings tested
upchuck. (Even at 1rpm, a significant fraction of the people tested upchuck;
you need to get the rotation rate down to about 0.25 rpm in order for the
general population to not upchuck.)


The best bit about this post is the knowledge that, in the future, there
will be dozens of bright young engineering students taking their
"Orbital Habitats Design" classes, and sitting dozing whilst someone
sketches various torii and explains the social importance of the "vomit
coefficient".

:-)

Of course, .25rpm would mean you'd have to bring the torus out to, what,
2 miles? Makes it an even less enticing prospect...

--
-Andrew Gray

  #19  
Old August 21st 03, 11:50 PM
Jochem Huhmann
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Default artificial gravity a different idea...maybe?

Manfred Bartz writes:

Zero G is not a problem for short durations, say a week or two.
Beyond that it becomes an increasing problem. As you can see from
reports about the condition of astronauts returning after extended
stays in zero G, they need a few weeks to recover to the point where
they function normally again. Regaining the original bone density
takes much longer (years).


What I've been wondering for some time now: A person constantly living
in zero G, would he suffer any illness from that loss of bone mass etc.?
Imagine a space habitat where people are born, live and die. I think
they would need some kind of training to make sure they can perform
other things than pressing a button now and then (which we on earth get
a minimum of by just walking around), but would there be a need for this
massive training done i.e. on the ISS?

Or, pushing this further: A child being born and growing up in 0g. Would
it just adopt to this conditions and feel fine, although probably unable
to withstand 1g at all?

OK, probably nobody knows about that... ;-)


Jochem

--
"A designer knows he has arrived at perfection not when there is no
longer anything to add, but when there is no longer anything to take
away." - Antoine de Saint-Exupery
  #20  
Old August 22nd 03, 12:10 AM
Jochem Huhmann
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Default artificial gravity a different idea...maybe?

"Christopher M. Jones" writes:

What are these health consequences?


Loss of bone and muscle density (the bone density loss is the
real nasty one, think osteoporosis).

What is the g threshold or range over
which they occur?


We don't know. All we know is that they don't happen at 1 g
and they do happen in micro-g. What happens in the range in
between is just speculation.


As far as I know this is not a direct consequence of zero-g (or micro-g)
but a consequence of missing that load on bones and muscles our body is
evolutionary optimized for. One could imagine that a person living in
micro-g but doing really hard work with frequent heavy loads on bones
and muscles would do quite well. And the other way round, people in 1g
just laying in bed for months *do* suffer loss of bone and muscle
density quite similar to those in zero-g.


Jochem

--
"A designer knows he has arrived at perfection not when there is no
longer anything to add, but when there is no longer anything to take
away." - Antoine de Saint-Exupery
 




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