I need a little help with some minor points about orbital precession
around the sun.

Many of the habitat designs (O'Neill Cylinders, Stanford Torus,
Bernal Sphere) design the radiators so that they are edge-on to the
sun.

I can see how this makes sense if the habitat orbit is similar to a
planet's.

If the orbit is around a point at 90,000 miles from the L5 point, or
is a 2:1 resonant orbit that ranges from 100,000 to 200,000 miles
from earth and has a period of two weeks, then will orbital
precession still be as exact?

I guess the central question is can the habitat precess so exactly
as to design the radiators edge-on to the sun and is this precession
independent of the habitat orbit? I'm inclined to think precession
is independent of orbit but would like some confirmation. Also,
would varying gravity encountered along the orbit affect the
automated precession rate of the non-rotating habitat structures?

The orbital mechanics are giving me a headache! I'm trying to
imagine how the forces would be applied when a torus is rotating,
needs to precess with the sun, and is in a 2:1 resonant orbit with
the earth and lunar gravity varying during every two week period.

Or will this not be as automatic for a torus? Will there have to be
a "precession engineer" who'll have to calculate how much to precess
the non-rotating structures of the torus so as to have them be edge-
on to the sun, and execute the procedure with attached drives? If
this is indeed the case, then what effect will the precession motion
have on the de-spin coupler, and the parts of the structure that are
designed for zero-g forces?

I sure hope somebody can set me straight on this!

The orbital precession and parameters have no relation to the spin axis of
the habitat.

So the radiators can always be edge on to the Sun, regardless of the orbital
parameters.

Well, that's straight forward enough. Good.

What issues would there be for a rotating habitat and a non-rotating
radiator that needs to precess? Mechanical stresses? How can it be
accomplished? etc. Any thoughts?

>
> The orbital precession and parameters have no relation to the spin
axis of
> the habitat.
>
> So the radiators can always be edge on to the Sun, regardless of
the orbital
> parameters.
>
> > I need a little help with some minor points about orbital
precession
> > around the sun.
> >
> > Many of the habitat designs (O'Neill Cylinders, Stanford Torus,
> > Bernal Sphere) design the radiators so that they are edge-on to
the
> > sun.
> >
> > I can see how this makes sense if the habitat orbit is similar
to a
> > planet's.
> >
> > If the orbit is around a point at 90,000 miles from the L5
point, or
> > is a 2:1 resonant orbit that ranges from 100,000 to 200,000 miles
> > from earth and has a period of two weeks, then will orbital
> > precession still be as exact?
> >
> > I guess the central question is can the habitat precess so
exactly
> > as to design the radiators edge-on to the sun and is this
precession
> > independent of the habitat orbit? I'm inclined to think
precession
> > is independent of orbit but would like some confirmation. Also,
> > would varying gravity encountered along the orbit affect the
> > automated precession rate of the non-rotating habitat structures?
> >
> > The orbital mechanics are giving me a headache! I'm trying to
> > imagine how the forces would be applied when a torus is rotating,
> > needs to precess with the sun, and is in a 2:1 resonant orbit
with
> > the earth and lunar gravity varying during every two week period.
> >
> > Or will this not be as automatic for a torus? Will there have to
be
> > a "precession engineer" who'll have to calculate how much to
precess
> > the non-rotating structures of the torus so as to have them be
edge-
> > on to the sun, and execute the procedure with attached drives? If
> > this is indeed the case, then what effect will the precession
motion
> > have on the de-spin coupler, and the parts of the structure that
are

> Well, that's straight forward enough. Good.
>
> What issues would there be for a rotating habitat and a non-rotating
> radiator that needs to precess? Mechanical stresses? How can it be
> accomplished? etc. Any thoughts?
>

Why does it need to precess ?

>
> > Well, that's straight forward enough. Good.
> >
> > What issues would there be for a rotating habitat and a non-
rotating
> > radiator that needs to precess? Mechanical stresses? How can it
be
> > accomplished? etc. Any thoughts?
> >
> Why does it need to precess ?

I thought it needed to in order to always point the radiator edge
in the direction of the sun. If the radiator is non-rotating doesn't
that pose a problem?

Your asking this question makes me wonder if I've missed something
elementary in my visualization of the process. Have I?

In order for a radiator to be continuously edge on to the Sun it is
sufficient that the spin axis of the system be perpendicular to the plane of
the orbit around the Sun.

The radiator will need to be on a despun platform.

This is standard practice for spacecraft radiators, take a look at the ISS
design.

OK. You've answered my question but I'm still left with some
misunderstanding (probably because I'm working with a faulty
assumption which I can't identify yet.) If you have a few more
moments, let's continue with the lesson.

With the radiator on the despun platform and the spin axis being
perpendicular to the plane of the orbit around the sun, if the
radiator is immobile, won't the sun, over the course of a year,
shine on all sides of that radiator?

What keeps the radiator edge-on to the sun if not some motion
imparted at the habitat?

Do we just line it up and leave it? Is there no further action
required on our part?

>
> In order for a radiator to be continuously edge on to the Sun it is
> sufficient that the spin axis of the system be perpendicular to
the plane of
> the orbit around the Sun.
>
> The radiator will need to be on a despun platform.
>
> This is standard practice for spacecraft radiators, take a look at
the ISS
> design.
>
> > > > Well, that's straight forward enough. Good.
> > > >
> > > > What issues would there be for a rotating habitat and a non-
> > rotating
> > > > radiator that needs to precess? Mechanical stresses? How can
it
> > be
> > > > accomplished? etc. Any thoughts?
> > > >
> > >
> > > Why does it need to precess ?
> >
> > I thought it needed to in order to always point the radiator edge
> > in the direction of the sun. If the radiator is non-rotating
doesn't
> > that pose a problem?
> >
> > Your asking this question makes me wonder if I've missed
something

>
> With the radiator on the despun platform and the spin axis being
> perpendicular to the plane of the orbit around the sun, if the
> radiator is immobile, won't the sun, over the course of a year,
> shine on all sides of that radiator?
>

Precisely.

> What keeps the radiator edge-on to the sun if not some motion
> imparted at the habitat?
>

For this very reason the despun platform is not exaclty despun, it is slightly overspun.

> Do we just line it up and leave it? Is there no further action
> required on our part?
>

Also, the friction of the bearings changes, the spacecraft has to contantly vary the despin motor power to keep it tracking to the Sun.

There are dozens of communications satellites which are doing this even as we type.

Like I said, standard spacecraft design which has been in use for decades.