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Another problem with longer flights



 
 
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  #1  
Old January 27th 09, 04:02 PM posted to sci.space.policy
jacob navia[_2_]
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Posts: 145
Default Another problem with longer flights

In any trip for humans beyond the moon (mars and beyond)
artificial gravity is a necessity.

Space.com reports:
[1]

quote
Astronauts that spend long months aboard the International Space Station
lose bone strength faster than previously thought and have a higher risk
of breaking their hips later in life, a new study reports.

A survey of 13 space station astronauts found that their bone strength
dipped by at least 14 percent on the average during their half-year
stays aboard the orbiting laboratory.

Three of the astronauts lost up to 30 percent of their bone strength
during their long-duration spaceflights, putting them on par with the
bone strength of older women with osteoporosis on Earth, the study
reported.
end quote

If in only 6 months trips they lose 14% of their bone strength,
in a trip of 2 years (the minimum time for a Mars trip) the strength
of their bones would disminish in such a measure that it would be a one
way trip only. They could not resist earth gravity when they come back.

This means that artificial gravity is a must for any trip that takes
more than 2-3 months. Note that the risk of breaking their bones much
later in life increases since apparently is very difficult to get
the lost strength back.

This is another big problem with humans in space and with human
spaceflight.

[1]
http://www.space.com/scienceastronom...ngth-loss.html
--
jacob navia
jacob at jacob point remcomp point fr
logiciels/informatique
http://www.cs.virginia.edu/~lcc-win32
  #2  
Old January 28th 09, 09:43 PM posted to sci.space.policy
Pat Flannery
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Posts: 18,465
Default Another problem with longer flights



Borked Pseudo Mailed wrote:
The evolution of species on Earth has depended on gravity for billions of years. Why are we so ignorant to think that we can solve the adverse effects of weightlessness within a couple of decades? Why aren't we more pragmatic?

Weight.
Building something that spins and generates 1 g like in 2001 means its
going to have to be huge, as studies have shown that unless it's around
400' in diameter the crew are going to get sick as they move around
inside of it from having "up" constantly changing between their head and
feet as they move from point to point on its periphery.
This is going to cause dizziness and nausea.
The centrifuge aboard the Discovery was only generating 1/6 g and even
then it was way too small to prevent the astronauts from getting sick:
http://www.visual-memory.co.uk/amk/doc/gaffe.html

"And although the Discovery's centrifuge scenes are superbly executed,
in the scene at Space Station Five it's quite obvious the actors in
these scenes are descending a ramp as they walk 'around' the wheel of
the station from the background to the foreground. The Discovery's 38ft.
centrifuge itself is the object of some debate: Clarke and science
advisor Ordway have admitted that, as impressive as it looks, the
centrifuge would need to have been many times larger or the Corriolus
effect in the inner ear would have caused uncontrollable nausea in the
crew members. There are also many questions as to the effect of the
torque of rotation on objects inside a rapidly rotating centrifuge.
According to Ordway's writings, the decision was made to have the
centrifuge generate 1/6 G lunar gravity. Of course, rapid exercise such
as Poole's running would be impossible in such low gravity."

Pat
  #3  
Old January 28th 09, 10:30 PM posted to sci.space.policy
jacob navia[_2_]
external usenet poster
 
Posts: 145
Default Another problem with longer flights

Pat Flannery wrote:


Borked Pseudo Mailed wrote:
The evolution of species on Earth has depended on gravity for
billions of years. Why are we so ignorant to think that we can solve
the adverse effects of weightlessness within a couple of decades? Why
aren't we more pragmatic?

Weight.
Building something that spins and generates 1 g like in 2001 means its
going to have to be huge, as studies have shown that unless it's around
400' in diameter the crew are going to get sick as they move around
inside of it from having "up" constantly changing between their head and
feet as they move from point to point on its periphery.
This is going to cause dizziness and nausea.
The centrifuge aboard the Discovery was only generating 1/6 g and even
then it was way too small to prevent the astronauts from getting sick:
http://www.visual-memory.co.uk/amk/doc/gaffe.html


Exactly. That is why human space travel will have to wait
until we can build huge spaceships.

To just go to Mars, with a 2-3 year stay in space, we would need
a huge, rotating, ship, shielded from space radiation by several
meters of water. This will not be feasible with current technology.

We will need a radically new way of accessing space before such ships
become possible.

With the *current* knowledge we have, automatic robotic exploring is the
only way to go.


--
jacob navia
jacob at jacob point remcomp point fr
logiciels/informatique
http://www.cs.virginia.edu/~lcc-win32
  #4  
Old January 28th 09, 10:35 PM posted to sci.space.policy
Martha Adams
external usenet poster
 
Posts: 371
Default Another problem with longer flights

"Borked Pseudo Mailed" wrote in message
d.net...
"jacob navia" wrote in message
...
In any trip for humans beyond the moon (mars and beyond)
artificial gravity is a necessity.

Space.com reports:
[1]

quote
Astronauts that spend long months aboard the International Space
Station
lose bone strength faster than previously thought and have a higher
risk
of breaking their hips later in life, a new study reports.

A survey of 13 space station astronauts found that their bone
strength
dipped by at least 14 percent on the average during their half-year
stays aboard the orbiting laboratory.

Three of the astronauts lost up to 30 percent of their bone strength
during their long-duration spaceflights, putting them on par with the
bone strength of older women with osteoporosis on Earth, the study
reported.
end quote

If in only 6 months trips they lose 14% of their bone strength,
in a trip of 2 years (the minimum time for a Mars trip) the strength
of their bones would disminish in such a measure that it would be a
one
way trip only. They could not resist earth gravity when they come
back.

This means that artificial gravity is a must for any trip that takes
more than 2-3 months. Note that the risk of breaking their bones much
later in life increases since apparently is very difficult to get
the lost strength back.

This is another big problem with humans in space and with human
spaceflight.


I've been advocating artificial gravity for many many years now, but
it seems NASA is suffering from some sort of tunnel vision, convinced
they can solve the ill effects of weightlessness by medicines and
exercise.

That is why '2001 A Space Odyssey' is still one of my favorite movies,
because both the space station and Discovery used artificial gravity
systems, and it seems people in the 60's were far better informed than
we are. Decades of research has come up naught, there *is no* way to
combat the absence of gravity but to produce it artificially. The
evolution of species on Earth has depended on gravity for billions of
years. Why are we so ignorant to think that we can solve the adverse
effects of weightlessness within a couple of decades? Why aren't we
more pragmatic?


================================================== =

Well, researchers are working on it. I can't speak for NASA, nor do I
think things are so simple our 'we' can include everyone. In the mean
time, Robert Zubrin answers this and very many other relevant questions
in his book, "The Case for Mars" (1996). There's lots of good resources
in cyberspace but I think Zubrin's book is the best place for someone to
start who wants to acquire the resources to do something constructive as
vs recycling old words.

Titeotwawki -- mha [sci.space.policy 2009 Jan 28]


  #5  
Old January 29th 09, 02:29 AM posted to sci.space.policy
Pat Flannery
external usenet poster
 
Posts: 18,465
Default Another problem with longer flights



Martha Adams wrote:

Well, researchers are working on it. I can't speak for NASA, nor do I
think things are so simple our 'we' can include everyone. In the mean
time, Robert Zubrin answers this and very many other relevant
questions in his book, "The Case for Mars" (1996). There's lots of
good resources in cyberspace but I think Zubrin's book is the best
place for someone to start who wants to acquire the resources to do
something constructive as vs recycling old words.


There's a way to do it...you don't need the whole wheel, just something
spinning 400 feet or more from its center of rotation.
Which means you can hang the thing you want to have gravity on the end
of a 400 foot cable to the center of rotation with a counterweight of
some sort on the opposite side of it...which can be another crewed area
or something like a reactor.
My nuclear-thermal/ion propulsion spaceship idea (model he
http://www.starshipmodeler.com/gallery/pf_disc.htm )
....uses this by having the whole ship rotate around its center, where
the de-spun ion engines and low gravity areas are located. the crew
lives at the front end, and over 800 feet away are the nuclear power
plant and nuclear-thermal engines serving as a counterweight. The
de-spun ion engines and observation and communication gear are at the
center of rotation, sliding back and forth on tracks to keep then
centered as the center point of rotation changes due to loss of mass of
expendables at either end, or the secondary ships docking and undocking
as they explore the moons of Saturn.
Although it's never shown in "2001", the movie's Discovery* is
perfectly designed to do this also as you can see in the rotating scenes
in "2010" where they board the Discovery from the center communications
area.
I wonder if the original idea was to have it rotating in the movie, as
it would hearken back to the ape throwing the rotating bone into the air
at the beginning of the movie.

* Mine is called Discovery because NASA decided to name it after the one
in the movie and the Shuttle, the way they named the Shuttle Enterprise
after the one in Star Trek.

Pat
  #6  
Old January 29th 09, 04:13 AM posted to sci.space.policy
Len Lekx
external usenet poster
 
Posts: 123
Default Another problem with longer flights

On Wed, 28 Jan 2009 22:30:42 +0100, jacob navia
wrote:

Building something that spins and generates 1 g like in 2001 means its
going to have to be huge, as studies have shown that unless it's around
400' in diameter the crew are going to get sick as they move around

Exactly. That is why human space travel will have to wait
until we can build huge spaceships.


Not really - put two ship-sections on the end of a tether, and swing
them around their center-of-mass like a bolo. You've got gravity AND
a small ship.
  #7  
Old January 29th 09, 04:40 AM posted to sci.space.policy
[email protected]
external usenet poster
 
Posts: 1,516
Default Another problem with longer flights

On Jan 28, 4:35�pm, "Martha Adams" wrote:
"Borked Pseudo Mailed" wrote in messagenews:e7b782c2dc2312c4b1e98631cfe752c0@pseud o.borked.net...





"jacob navia" wrote in message
...
In any trip for humans beyond the moon (mars and beyond)
artificial gravity is a necessity.


Space.com reports:
[1]


quote
Astronauts that spend long months aboard the International Space
Station
lose bone strength faster than previously thought and have a higher
risk
of breaking their hips later in life, a new study reports.


A survey of 13 space station astronauts found that their bone
strength
dipped by at least 14 percent on the average during their half-year
stays aboard the orbiting laboratory.


Three of the astronauts lost up to 30 percent of their bone strength
during their long-duration spaceflights, putting them on par with the
bone strength of older women with osteoporosis on Earth, the study
reported.
end quote


If in only 6 months trips they lose 14% of their bone strength,
in a trip of 2 years (the minimum time for a Mars trip) the strength
of their bones would disminish in such a measure that it would be a
one
way trip only. They could not resist earth gravity when they come
back.


This means that artificial gravity is a must for any trip that takes
more than 2-3 months. Note that the risk of breaking their bones much
later in life increases since apparently is very difficult to get
the lost strength back.


This is another big problem with humans in space and with human
spaceflight.


I've been advocating artificial gravity for many many years now, but
it seems NASA is suffering from some sort of tunnel vision, convinced
they can solve the ill effects of weightlessness by medicines and
exercise.


That is why '2001 A Space Odyssey' is still one of my favorite movies,
because both the space station and Discovery used artificial gravity
systems, and it seems people in the 60's were far better informed than
we are. Decades of research has come up naught, there *is no* way to
combat the absence of gravity but to produce it artificially. The
evolution of species on Earth has depended on gravity for billions of
years. Why are we so ignorant to think that we can solve the adverse
effects of weightlessness within a couple of decades? Why aren't we
more pragmatic?


================================================== =

Well, researchers are working on it. �I can't speak for NASA, nor do I
think things are so simple our 'we' can include everyone. �In the mean
time, Robert Zubrin answers this and very many other relevant questions
in his book, "The Case for Mars" (1996). �There's lots of good resources
in cyberspace but I think Zubrin's book is the best place for someone to
start who wants to acquire the resources to do something constructive as
vs recycling old words.

Titeotwawki -- mha �[sci.space.policy 2009 Jan 28]- Hide quoted text -

- Show quoted text -


or cut the travel time dramatically by using nuclear engine for mars
mission. a few months each way plus time on mars.

pair a hot nuke engine with a small cargo pod for fast emergency
supplies.

although i agree robotic exploration is best and could be used to
leapfrog AI and other robotics.

  #8  
Old January 29th 09, 05:14 AM posted to sci.space.policy
Greg D. Moore \(Strider\)
external usenet poster
 
Posts: 2,865
Default Another problem with longer flights

"Len Lekx" wrote in message
...
On Wed, 28 Jan 2009 22:30:42 +0100, jacob navia
wrote:

Building something that spins and generates 1 g like in 2001 means its
going to have to be huge, as studies have shown that unless it's around
400' in diameter the crew are going to get sick as they move around

Exactly. That is why human space travel will have to wait
until we can build huge spaceships.


Not really - put two ship-sections on the end of a tether, and swing
them around their center-of-mass like a bolo. You've got gravity AND
a small ship.


And other issues. Such as how do you perform in-flight maneuvers?

And what happens if you can't keep the line taught.

We definitely need to do more research in this area before we can claim it's
easy.


--
Greg Moore
Ask me about lily, an RPI based CMC.


  #9  
Old January 29th 09, 05:25 AM posted to sci.space.policy
Fred J. McCall[_3_]
external usenet poster
 
Posts: 10,018
Default Another problem with longer flights

jacob navia wrote:

:Pat Flannery wrote:
:
:
: Borked Pseudo Mailed wrote:
: The evolution of species on Earth has depended on gravity for
: billions of years. Why are we so ignorant to think that we can solve
: the adverse effects of weightlessness within a couple of decades? Why
: aren't we more pragmatic?
:
: Weight.
: Building something that spins and generates 1 g like in 2001 means its
: going to have to be huge, as studies have shown that unless it's around
: 400' in diameter the crew are going to get sick as they move around
: inside of it from having "up" constantly changing between their head and
: feet as they move from point to point on its periphery.
: This is going to cause dizziness and nausea.
: The centrifuge aboard the Discovery was only generating 1/6 g and even
: then it was way too small to prevent the astronauts from getting sick:
: http://www.visual-memory.co.uk/amk/doc/gaffe.html
:
:
:Exactly. That is why human space travel will have to wait
:until we can build huge spaceships.
:
:To just go to Mars, with a 2-3 year stay in space, we would need
:a huge, rotating, ship, shielded from space radiation by several
:meters of water. This will not be feasible with current technology.
:
:We will need a radically new way of accessing space before such ships
:become possible.
:
:With the *current* knowledge we have, automatic robotic exploring is the
nly way to go.
:

You mean the current knowledge YOU have. The rest of us are somewhat
brighter and better informed.

No "huge, rotating, ship, [sic]" is required. A much smaller ship, a
rope, and a counterweight will achieve the same end.


--
"Some people get lost in thought because it's such unfamiliar
territory."
--G. Behn
  #10  
Old January 29th 09, 05:27 AM posted to sci.space.policy
Fred J. McCall[_3_]
external usenet poster
 
Posts: 10,018
Default Another problem with longer flights

"Greg D. Moore \(Strider\)" wrote:

:"Len Lekx" wrote in message
.. .
: On Wed, 28 Jan 2009 22:30:42 +0100, jacob navia
: wrote:
:
: Building something that spins and generates 1 g like in 2001 means its
: going to have to be huge, as studies have shown that unless it's around
: 400' in diameter the crew are going to get sick as they move around
:Exactly. That is why human space travel will have to wait
:until we can build huge spaceships.
:
: Not really - put two ship-sections on the end of a tether, and swing
: them around their center-of-mass like a bolo. You've got gravity AND
: a small ship.
:
:And other issues. Such as how do you perform in-flight maneuvers?
:

Reel in the weight, maneuver, reel it back out, and respin.

:
:And what happens if you can't keep the line taught.
:

Then you have much bigger problems, since that would mean that the
basic laws of physics had broken down.


--
"Ignorance is preferable to error, and he is less remote from the
truth who believes nothing than he who believes what is wrong."
-- Thomas Jefferson
 




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