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Orbital Gravity Lab?



 
 
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  #1  
Old May 3rd 18, 04:23 PM posted to sci.space.policy
David Spain
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Posts: 2,901
Default Orbital Gravity Lab?

What would it take to get such a thing in orbit? Are there any
*knowledgeable* readers left in sci.space.policy that can comment on
this (Fred, Jeff and Greg excluded)?

In my un-humble opinion this is the most important laboratory for long
term crewed space missions that NASA could orbit. In fact, if we are
wasting money on SLS anyway, let's make this its VERY FIRST payload. It
would never "pay for itself" because it could be done far more cheaply
with existing boosters, but if the money is being stuffed down a hole
anyway, why not? And it doesn't need an upper-stage capable of TLI
unlike the so-called Deep Space Gateway. In fact that would be totally
counterproductive. You'd want easy access to this from (soon to be)
existing LEO transports for a variety of reasons.

Nor does it *have* to be a NASA project. But NASA would be the ideal
supervisory agency since they have the ability to bang heads together to
get the various aerospace contractors to co-operate rather than compete.

But this presupposes NASA stops competing against US industry for launch
infrastructure....

Dave
  #2  
Old May 3rd 18, 11:00 PM posted to sci.space.policy
David Spain
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Posts: 2,901
Default Orbital Gravity Lab?

On 5/3/2018 2:07 PM, JF Mezei wrote:
On 2018-05-03 11:23, David Spain wrote:
What would it take to get such a thing in orbit? Are there any
*knowledgeable* readers left in sci.space.policy that can comment on
this (Fred, Jeff and Greg excluded)?



By "Orbital Gravity Lab", are you refering to something like the
original Centrifuge module for ISS? (but perhaps larger scale for himan
habitation).


I think all proposed centrifuge modules[1-3] for the ISS were doomed
from the get go and I would not go that route. Without shuttle it will
be awhile before any new modules are added to the ISS (if ever).

I would prefer a free flyer over something attached to the ISS. But
placing it close to the ISS in a co-orbit could be useful, but not
necessary. If it's to serve as a base design for a Deep Space Gateway
(or something akin to the Nautilus-X) a lower inclination orbit or an
orbital inclination for a Hohmann Transfer Orbit with a suitable
propulsion module might be preferable.

Human habitation yes. Animal and plant habitation also. Assuming
potential Mars residents will want to take along both. Animal will be a
problem with the PETA folks tho. Might get away with "non-exotics" or
domestic animals with human experimenters also being their owners. Thus
not putting their "pets" at any more risk than they themselves are.
(important - "To the best of our knowledge").

Of course if NASA continues to dilly-dally around with SLS, Musk can
simply orbit a BFS and put it into a slow spin and accomplish the same
things. Elon seems serious about Mars. I actually expect this will
happen not long after a BFS achieves first orbit. Probably as part of a
series of "long duration experiments" on BFS in LEO.

Dave

[1] http://iss.jaxa.jp/iss/contribution/issjpdoc3_2_e.html
[2] https://en.wikipedia.org/wiki/Centri...dations_Module
[3] https://ipfs.io/ipfs/QmXoypizjW3WknF...autilus-X.html



  #3  
Old May 4th 18, 01:30 AM posted to sci.space.policy
Fred J. McCall[_3_]
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Posts: 10,018
Default Orbital Gravity Lab?

David Spain wrote on Thu, 3 May 2018 18:00:04
-0400:

On 5/3/2018 2:07 PM, JF Mezei wrote:
On 2018-05-03 11:23, David Spain wrote:
What would it take to get such a thing in orbit? Are there any
*knowledgeable* readers left in sci.space.policy that can comment on
this (Fred, Jeff and Greg excluded)?



By "Orbital Gravity Lab", are you refering to something like the
original Centrifuge module for ISS? (but perhaps larger scale for himan
habitation).


I think all proposed centrifuge modules[1-3] for the ISS were doomed
from the get go and I would not go that route. Without shuttle it will
be awhile before any new modules are added to the ISS (if ever).


Some five modules have been added to ISS since the last Shuttle
flight. Even large modules only mass 15-20 tonnes, which is within
the capability of Falcon 9.


I would prefer a free flyer over something attached to the ISS. But
placing it close to the ISS in a co-orbit could be useful, but not
necessary. If it's to serve as a base design for a Deep Space Gateway
(or something akin to the Nautilus-X) a lower inclination orbit or an
orbital inclination for a Hohmann Transfer Orbit with a suitable
propulsion module might be preferable.


That means you need a lot more infrastructure, since you can't rely on
things like power and climate control from ISS. And if you want the
Russians to play, you have to go to the higher inclination orbit so
they can reach it. I personally am not a fan of 'international'
efforts and the additional infrastructure for a free flyer certainly
isn't a show stopper.

Human habitation yes. Animal and plant habitation also. Assuming
potential Mars residents will want to take along both. Animal will be a
problem with the PETA folks tho. Might get away with "non-exotics" or
domestic animals with human experimenters also being their owners. Thus
not putting their "pets" at any more risk than they themselves are.
(important - "To the best of our knowledge").

Of course if NASA continues to dilly-dally around with SLS, Musk can
simply orbit a BFS and put it into a slow spin and accomplish the same
things. Elon seems serious about Mars. I actually expect this will
happen not long after a BFS achieves first orbit. Probably as part of a
series of "long duration experiments" on BFS in LEO.


'Spinning' a BFS makes a lot of things too hard and it's not really
big enough to let you have appreciable spin gravity without making
people sick.


--
"The reasonable man adapts himself to the world; the unreasonable
man persists in trying to adapt the world to himself. Therefore,
all progress depends on the unreasonable man."
--George Bernard Shaw
  #4  
Old May 4th 18, 01:56 AM posted to sci.space.policy
Alain Fournier[_3_]
external usenet poster
 
Posts: 548
Default Orbital Gravity Lab?

On May/3/2018 at 8:30 PM, Fred J. McCall wrote :
David Spain wrote on Thu, 3 May 2018 18:00:04
-0400:

On 5/3/2018 2:07 PM, JF Mezei wrote:
On 2018-05-03 11:23, David Spain wrote:
What would it take to get such a thing in orbit? Are there any
*knowledgeable* readers left in sci.space.policy that can comment on
this (Fred, Jeff and Greg excluded)?


By "Orbital Gravity Lab", are you refering to something like the
original Centrifuge module for ISS? (but perhaps larger scale for himan
habitation).


I think all proposed centrifuge modules[1-3] for the ISS were doomed
from the get go and I would not go that route. Without shuttle it will
be awhile before any new modules are added to the ISS (if ever).


Some five modules have been added to ISS since the last Shuttle
flight. Even large modules only mass 15-20 tonnes, which is within
the capability of Falcon 9.


I would prefer a free flyer over something attached to the ISS. But
placing it close to the ISS in a co-orbit could be useful, but not
necessary. If it's to serve as a base design for a Deep Space Gateway
(or something akin to the Nautilus-X) a lower inclination orbit or an
orbital inclination for a Hohmann Transfer Orbit with a suitable
propulsion module might be preferable.


That means you need a lot more infrastructure, since you can't rely on
things like power and climate control from ISS. And if you want the
Russians to play, you have to go to the higher inclination orbit so
they can reach it. I personally am not a fan of 'international'
efforts and the additional infrastructure for a free flyer certainly
isn't a show stopper.

Human habitation yes. Animal and plant habitation also. Assuming
potential Mars residents will want to take along both. Animal will be a
problem with the PETA folks tho. Might get away with "non-exotics" or
domestic animals with human experimenters also being their owners. Thus
not putting their "pets" at any more risk than they themselves are.
(important - "To the best of our knowledge").

Of course if NASA continues to dilly-dally around with SLS, Musk can
simply orbit a BFS and put it into a slow spin and accomplish the same
things. Elon seems serious about Mars. I actually expect this will
happen not long after a BFS achieves first orbit. Probably as part of a
series of "long duration experiments" on BFS in LEO.


'Spinning' a BFS makes a lot of things too hard and it's not really
big enough to let you have appreciable spin gravity without making
people sick.


I agree with you. But one of the things that would be interesting to
investigate is whether a small gravity would help. I don't think a
one percent of a g would help much. But it would be nice to know that,
not just think it.


Alain Fournier
  #5  
Old May 4th 18, 06:34 AM posted to sci.space.policy
Fred J. McCall[_3_]
external usenet poster
 
Posts: 10,018
Default Orbital Gravity Lab?

Alain Fournier wrote on Thu, 3 May 2018
20:56:01 -0400:

On May/3/2018 at 8:30 PM, Fred J. McCall wrote :

'Spinning' a BFS makes a lot of things too hard and it's not really
big enough to let you have appreciable spin gravity without making
people sick.


I agree with you. But one of the things that would be interesting to
investigate is whether a small gravity would help. I don't think a
one percent of a g would help much. But it would be nice to know that,
not just think it.


If you want a real 'gravity lab', I would suggest something other than
B330 modules attached to a tether so that they can change the distance
between them. Then you give them enough propulsion so that they can
keep a reasonable rotation rate to adjust for angular momentum effects
from moving them closer together or further apart. Then you can
select the gravity level you want to test at, do that for however long
you need to, then adjust the distance and test at a different level of
gravity.


--
"The reasonable man adapts himself to the world; the unreasonable
man persists in trying to adapt the world to himself. Therefore,
all progress depends on the unreasonable man."
--George Bernard Shaw
  #6  
Old May 4th 18, 11:14 AM posted to sci.space.policy
Fred J. McCall[_3_]
external usenet poster
 
Posts: 10,018
Default Orbital Gravity Lab?

JF Mezei wrote on Fri, 4 May 2018
01:29:36 -0400:


Reality check question:

If you build a rotating station that is big enough for humans, how much
of a challenge does it become to keep it "balanced" so rotation is
smooth and no precession?


'Balanced' largely wouldn't be an issue, since the people would be a
tiny, tiny percentage of the mass of the station. Precession is
something different from what you think and has nothing to do with
'balance'. Unless it's built as two contrarotating pieces of equal
mass, it WILL precess.


Is it a question of having CMGs that constantly compensate for uneven
distribution of mass around the station? (think crewmember jogging
around it, or a group of people getting out of tehir distributed
bedrooms and gathering for breakfast).


You'll need some reaction wheels to control pointing and some engines
to unload the reaction wheels when they become saturated. Think about
the mass of the station when compared to the mass of a human being...


--
"Some people get lost in thought because it's such unfamiliar
territory."
--G. Behn
  #7  
Old May 4th 18, 02:12 PM posted to sci.space.policy
David Spain
external usenet poster
 
Posts: 2,901
Default Orbital Gravity Lab?

On 5/3/2018 8:30 PM, Fred J. McCall wrote:
David Spain wrote on Thu, 3 May 2018 18:00:04
-0400:

On 5/3/2018 2:07 PM, JF Mezei wrote:
On 2018-05-03 11:23, David Spain wrote:
What would it take to get such a thing in orbit? Are there any
*knowledgeable* readers left in sci.space.policy that can comment on
this (Fred, Jeff and Greg excluded)?


By "Orbital Gravity Lab", are you refering to something like the
original Centrifuge module for ISS? (but perhaps larger scale for himan
habitation).


I think all proposed centrifuge modules[1-3] for the ISS were doomed
from the get go and I would not go that route. Without shuttle it will
be awhile before any new modules are added to the ISS (if ever).


Some five modules have been added to ISS since the last Shuttle
flight. Even large modules only mass 15-20 tonnes, which is within
the capability of Falcon 9.


OK I'll admit my mistake. Should have done some research first.
But I haven't seen any impetus to attach a centrifuge module to ISS
since the JAXA effort was shelved. A lot of proposals, yes, but nothing
concrete. If I recall, a major objection to these being attached to the
ISS is the vibrations they would induce that would interfere with other
experiments.


I would prefer a free flyer over something attached to the ISS. But
placing it close to the ISS in a co-orbit could be useful, but not
necessary. If it's to serve as a base design for a Deep Space Gateway
(or something akin to the Nautilus-X) a lower inclination orbit or an
orbital inclination for a Hohmann Transfer Orbit with a suitable
propulsion module might be preferable.


That means you need a lot more infrastructure, since you can't rely on
things like power and climate control from ISS.


Yes, without a doubt.

And if you want the
Russians to play, you have to go to the higher inclination orbit so
they can reach it. I personally am not a fan of 'international'
efforts and the additional infrastructure for a free flyer certainly
isn't a show stopper.


Not a priority for me either.

Human habitation yes. Animal and plant habitation also. Assuming
potential Mars residents will want to take along both. Animal will be a
problem with the PETA folks tho. Might get away with "non-exotics" or
domestic animals with human experimenters also being their owners. Thus
not putting their "pets" at any more risk than they themselves are.
(important - "To the best of our knowledge").

Of course if NASA continues to dilly-dally around with SLS, Musk can
simply orbit a BFS and put it into a slow spin and accomplish the same
things. Elon seems serious about Mars. I actually expect this will
happen not long after a BFS achieves first orbit. Probably as part of a
series of "long duration experiments" on BFS in LEO.


'Spinning' a BFS makes a lot of things too hard and it's not really
big enough to let you have appreciable spin gravity without making
people sick.



I need to do the math on this hand-wave of mine. It'd be interesting to
see, given the dimensions of BFS, how much spin could be induced before
ill crew effects and to what degree of 'g' that would yield. I'm not too
worried that BFS would not be able to handle a small amount of spin. I'd
assume that has to be factored into the design of any reliable spacecraft.

I suppose if you're building BFS's like assembly line Model T Fords, you
could probably devote two for a tethered setup, but you'd have to know
the ill effects of that on BFS hardware first assuming you'd want to
execute an crewed reentry via both vehicles. Another possibility is to
sacrifice a BFS to convert it into a 'space station' and add the
necessary hardware (wheel, etc.) to turn it into a gravity lab.

There are certainly MANY pre-cursor steps that need to be taken with BFS
before attempting a Mars expedition. Will be exciting times ahead.

Dave

  #8  
Old May 4th 18, 02:14 PM posted to sci.space.policy
David Spain
external usenet poster
 
Posts: 2,901
Default Orbital Gravity Lab?

On 5/4/2018 1:34 AM, Fred J. McCall wrote:
Alain Fournier wrote on Thu, 3 May 2018
20:56:01 -0400:

On May/3/2018 at 8:30 PM, Fred J. McCall wrote :

'Spinning' a BFS makes a lot of things too hard and it's not really
big enough to let you have appreciable spin gravity without making
people sick.


I agree with you. But one of the things that would be interesting to
investigate is whether a small gravity would help. I don't think a
one percent of a g would help much. But it would be nice to know that,
not just think it.


If you want a real 'gravity lab', I would suggest something other than
B330 modules attached to a tether so that they can change the distance
between them. Then you give them enough propulsion so that they can
keep a reasonable rotation rate to adjust for angular momentum effects
from moving them closer together or further apart. Then you can
select the gravity level you want to test at, do that for however long
you need to, then adjust the distance and test at a different level of
gravity.



Yep. I like that idea very much. Need to make sure we have the hardware
to be able to do that. In a perfect world maybe that could be two BFS's.
Maybe.


  #9  
Old May 4th 18, 02:22 PM posted to sci.space.policy
David Spain
external usenet poster
 
Posts: 2,901
Default Orbital Gravity Lab?

Another thing we just don't know, is whether it is good enough to have
limited exposure to 'g' to overcome the deficits of long duration in 0g
or low g. Thus it becomes routine to spend some time working out in a
centrifuge and the rest of the time in 0g or Mars gravity or whatever.
Call it extra-terrestrial PE....

I remember the classic video of one of the Skylab astronauts (was it
Conrad?) getting their exercise by 'running' around the inner
circumference of the Skylab habitation module.

  #10  
Old May 4th 18, 02:39 PM posted to sci.space.policy
David Spain
external usenet poster
 
Posts: 2,901
Default Orbital Gravity Lab?

On 5/4/2018 6:14 AM, Fred J. McCall wrote:

You'll need some reaction wheels to control pointing and some engines
to unload the reaction wheels when they become saturated. Think about
the mass of the station when compared to the mass of a human being...



As an aside apropos of nothing, I remember reading an elaboration I
think it was by A.C. Clarke himself about how the centrifuge would have
worked on the Discovery in 2001 A Space Odyssey. It may have been from
the book "The Making of 2001: A Space Odyssey". In it he mentions a
reaction wheel used to contain the angular momemtum of the centrifuge
when it was spun down and to assist in its spin up. I suppose if mass is
no object, it could also be used to counter-rotate against the
centrifuge if it was massive enough. On the Discovery the centrifuge was
completely contained within the spherical pressure hull.




 




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