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