[Laser] Laser retroreflectors on Sats

[James Whitfield]

Tom

According to the Wikipedia article on satellite flares, the Iridium flare 
comes from "one of the three door sized highly polished antennas" on each 
satellite, not from its solar collectors.  I beleive it also says something 
to the effect that one of the antennas is oriented to face the direction of 
travel, so it, and presumably the other two, rotates in inertial space as it 
goes through its orbit.  I am going from memory as I don't want to pull up 
the article again this late at night, but I think the inclination of the 
orbits are such that each changes the orientation of its plane as well.

I hope that might answer your question.  Not that it would make the task of 
trying to hit one with a light beam at a time when you could predict a 
useable reflection angle.

James
 n5gui


----- Original Message ----- 
From: "Tom Becker" <GTBecker at RighTime.com>
To: "Free Space LASER Communications" <laser at mailman.qth.net>
Sent: Monday, August 31, 2009 9:11 PM
Subject: Re: [Laser] Laser retroreflectors on Sats


> > ... Instead of the nice long 10 or 15 second brightening due to the
> sun having a half degree source size, lasers -being point sources-
> would have a much shorter length of maybe only a few milliseconds (a
> guess) not to mention a much smaller area over which they could be seen.
>
> But isn't the geometry simply wrong?  Iridium birds are stabilized to
> keep solar panels perpendicular to the Sun, aren't they?  If that is so,
> I don't believe there is any Iridium orbit position where the
> mirror-like panels - in which we see the Sun's reflection during an
> Iridium flare - will reflect an Earth-borne source back to the Earth.
> Is that wrong?
>
> Tom
>
>
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