Re: Bright Passes Obs for Rosat and Topex
Bart De Pontieu (bdp@cds.plasma.mpe-garching.mpg.de)
Fri, 17 Oct 1997 18:36:56 +0100 (MET)
On Fri, 17 Oct 1997, Walter Nissen wrote:
> Don Gardner, fn470@cleveland.freenet.edu, writes:
> > Some reflected light in the visible range probably wouldn't
> > affect efficency too much.
>
> Solar panels are highly reflective in the visual, much like a mirror. But
> hopefully most of the reflected sunlight is pointed directly back at the
> Sun.
According to a friend of mine who is scientific operator of Rosat, Rosat's
panels are kept directed towards the sun within a
cone of +- 20 degrees. Doesn't this mean that an observer could (assuming
perfect specular reflection) observe the reflection of the sun (on Rosat's
solar panels), up to a phase angle of 40 degrees?
> > I don't believe that Rosat or Topex have mirror ar the Iridiums and DMSP
> > sats have. Any thoughts as the the cause?
>
> ROSAT = 20638 = 90- 49A and TOPEX = 22076 = 92- 52A are getting along in
> age. Perhaps they have lost attitude control and are tumbling out of
> control?
Rosat is, as of today, alive and kicking, so that cannot be the cause for
the bright glint.
Rosat is slewed twice during each orbit to avoid the Earth from blocking
the detector (at least this is what I've been told). It is during this
slewing manoeuver that the solar panels are kept directed towards the sun
with only an accuracy of +-20 degrees.
Perhaps Don saw this slewing manoeuver? What was the phase angle at the
time of the glint?
Cheers,
Bart, bart@satellite.eu.org
PS: and no thanks, I don't any monetary contributions to help pay the
electricity bill (see my [ADMIN] from yesterday) :-)