what orbit maxes sunlight w/ ship that faces same way, i.e., due to rotating axis pointing at sun

Thread view:

Enable EMail Alerts

Start New Thread

Thread rating:

alexwilliamrussell@yahoo.com - 12 Nov 2005 18:57 GMT

question: what orbit maxes sunlight w/ ship that faces same way, i.e.,
due to rotating axis pointing at sun - - - am trying to have large
glassed area always facing sun while in LEO, to avoid any even small
changes in sunlight due to not being sun-facing except for when in
earth's shadow.

1 how do current craft keep panels to sun, yet keep antennas pointing
to earth? do they bother to every minute adjust panels or just pick a
good layout and then shut off motors?

2 could circular panels spun up and gyro-locked to sun-direction
(which I suppose shifts 1/365 of 380 degrees each day?) max sunlight,
maybe carrying power to station via a special de-coupled wire (rather
than beaming power losses?)

3 any good using clouds of white dust (or "mirror" shiny dust) about
100 meters away in higher orbit (to avoid dust near craft) to bounce
back light when panels are not facing right way during part of orbit,

4 obviously, if orbiting around equator every orbit craft facing sun
so does "flips" as seen from earth, or not?

5 polar orbits, is there one (certain altitude) that always is head-on
to sun. sorry, my mind can't visualize this for some reason

sorry for the basic questions, hope some might lead to good thoughts

Reply to this Message

Ian Stirling - 17 Nov 2005 13:50 GMT

> question: what orbit maxes sunlight w/ ship that faces same way, i.e.,
> due to rotating axis pointing at sun - - - am trying to have large
> glassed area always facing sun while in LEO, to avoid any even small
> changes in sunlight due to not being sun-facing except for when in
> earth's shadow.

> 1 how do current craft keep panels to sun, yet keep antennas pointing
> to earth? do they bother to every minute adjust panels or just pick a
> good layout and then shut off motors?

Computers and other automation have been able to do this for some time -
it's constantly adjusted.

> 2 could circular panels spun up and gyro-locked to sun-direction
> (which I suppose shifts 1/365 of 380 degrees each day?) max sunlight,
> maybe carrying power to station via a special de-coupled wire (rather
> than beaming power losses?)

Pointing is really not a problem.
'gyro locked' is only very fractionally easier than pointing at mars,
or the real-time position of Madonna, downloaded from news services.

As an example.
One design might be a cylinder, rotating with its axis pointing at right
angles to the sun.
At the end-cap is a 5m window, through which a collector pointed at the
sun and rotating to keep it in sight shines the light.
This is a bit tricky - it requires care to keep the glass clean, but is
quite doable.
Then you take the light that comes in this window (in a 20 degree beam)
and reflect it so that it gives you desired day/night times.

Reply to this Message

Mike Combs - 17 Nov 2005 18:50 GMT

One thing to bear in mind when discussing a rotating object orbiting the sun
with its spin axis pointing at the sun is that something will have to turn
the spin axis to track the sun (by about 1 degree a day, at our distance).

So you'd better talk in terms of two connected counter-rotating objects, so
that the angular momentums cancel each other out. This is the solution that
Gerard O'Neill adopted for his Island 3 habitats, which had the same
requirement.

Signature

Regards,
Mike Combs
----------------------------------------------------------------------
Member of the National Non-sequitur Society. We may not make
much sense, but we do like pizza.

Reply to this Message

Space Forum / Space Flight / November 2005

what orbit maxes sunlight w/ ship that faces same way, i.e., due to rotating axis pointing at sun