Modular Orbital Transfer Vehicles and Spun Habitats.

Hi again, and thanks again for the brilliant answers to my other
problems.

I have a few more questions I though I might propose to you because
I've noticed that quite often what appears to be relatively simple
concepts here have hidden and serious ramifications to the less-than-
knowledgable.

I'm postulating a crowded solar system with the main destinations
being the major bodies, major asteroids and La Grange points, the last
where I institute my handwavium interstellar jump drive.

To facilitate this I'd like to postulate modular OTVs. The idea being
that each 'clip on' module has its own drive to maintain the power to
mass ratio. The connection points incorporate docking, transfer, power
and control interfaces. This mandates that all my OTVs have a standard
amount of delta V available to them, no matter what they're carrying.

Now, here comes the questions;

- Can I boost these unmanned sections from various places and hook
them up mid-flight?
So, saying I'm launching my basic OTV from 4 Vesta on a rescue mission
but I need a specialist medical module from 1 Ceres. Can I launch this
module on remote pilot and hook up mid-flight?

- Spun habitats.
For long duration missions I'd like to have a spun habitat module that
can connect to the primary OTV core chassis. I have been unable to
find a spun habitat radius that is large enough to avoid the
equilibrium. Can anyone tell me what would be a minimum spun habitat
radius? What if the crew had surgically modified inner ears, is that
possible?
Also, I'm concerned about the torque transmitted to the same chassis
as the central spun habitat hub is connected to the chassis a 90º.
Will this be a concern? If it is, can I have a layer of counter-
rotating shielding spinning faster to offset the torque?

- Multiple drives.
Is it in any way practical and useful to have two different drives on
the craft? I was thinking an ion or plasma drive for steady boost and
some sort of reaction engine for an initial push.

Thanks in advance,
Jim/ChalkLine
.