Re: [APML] OT: Satellite orbital taxonomy

[steve banbury <banburys@sonic.net>]

Also unclear why glass would hide metal components (e.g. electronics boxes
and interconnecting harness from RF illumination by the pulsed radar.
Structural elements and prop tanks could be GFRP or Fiberglass with reduced
RF signature.

Has anybody actually made an attempt to answer Jim Janusz' original
question as to which satellite he had imaged?

Steve


At 09:58 AM 5/24/02 -0500, you wrote:
>depending on orbit height, that glass is gong to be trashed pretty quickly
from on orbit debris or in higher orbits from various particles from solar
wind to just small debris in the universe.
>
>>>> rybskip@idcnet.com 5/24/02 2:39:11 AM >>>
>Dear All,
>
>    Matt was spot-on concerning the stealth technology.  And he was almost
>entirely right about the IR luminosity.  Why?
>
>    The satellite hid behind a large sheet of very clean, seamless, flat
>glass.  It would not have been antireflection-coated, otherwise it would
>not have served its primary purpose of hiding the satellite from pulsed
>radar from below.  Under specific Sun-plate-Earth geometry, the Sun would
>be reflected toward the observer from the entire sheet of glass:  it was
>visible to the unaided eye when glinting.
>
>     The satellite system was hot in the IR because it had a finite
>temperature and radiated in all directions, including through the glass.
>
>     Any dust or other material attached to the front surface (facing
>Earth) would be illuminated by the Sun and would be clearly visible at some
>level to Earth-bound observers (as it was to me, though it took a 2.7 meter
>telescope and a pulse-counting, panoramic detector to do it).
>
>Paul
>
>>At 11:57 PM 5/23/2002 -0400, Matt BenDaniel wrote:
>>>At 11:19 PM 5/23/2002 -0400, Matt BenDaniel wrote:
>>>>At 08:38 PM 5/23/2002 -0500, Paul M. Rybski wrote:
>>>>>     If you wanted to look down on an enemy's installations 24/7 but
>>>>>didn't want him to successfully detect you by diffuse reflection off of
>>>>>satellite surfaces or by Kelvin retroreflection off of your solid state
>>>>>detectors when he painted you with a pulsed laser and looked for
>>>>>reflections synchronously at the time of the expected return pulse,
>>>>>what would you hide the satellite behind?  (Hint:  What would make you
>>>>>invisible most of the time but glint brightly at only one orientation
>>>>>with respect to you and to the Sun?)  (Another hint: This object was
>>>>>the brightest infrared source in the sky -- after the Sun, of course --
>>>>>at 10 microns.  How could it be so bright in the IR but nearly
>>>>>invisible in the visible?)
>>>>
>>>>Use highly reflective flat surfaces. A cube shape would do it. You must
>>>>keep the faces from pointing straight down to Earth. The satellite is
>>>>bright at 10 microns because there is a 10 micron background glow in
>>>>every direction.
>>>
>>>No, no, the last part of my answer is wrong. If it reflected background
>>>radiation it would look just like the background. It must be blackbody
>>>radiation.
>>
>>Doh. No, that can't be it either. Blackbody radiation at 10u would not be
>>intense. How does the satellite downlink? 10u RF (highly encrypted of
>>course)?
>>
>>--
>>Matt BenDaniel
>>matt@starmatt.com 
>>http://starmatt.com 
>>
>>
>>--  APML Archives at <http://astro.umsystem.edu/apml/>  ---
>>             Unsubscribe at <majordomo@seds.org>
>
>
>
>________________________________________
>Paul M. Rybski, Ph.D.
>Associate Professor and former Chair, Dept. of Physics, and
>Director, Whitewater Observatory

>University of WI-Whitewater
>Whitewater, WI  53190-1790
>
>Office FAX:     (414) 472-5633
>Email address:  rybskip@uww.edu 
>
>
>
>--  APML Archives at <http://astro.umsystem.edu/apml/>  ---
>             Unsubscribe at <majordomo@seds.org>
>
>
>--  APML Archives at <http://astro.umsystem.edu/apml/>  ---
>             Unsubscribe at <majordomo@seds.org>
> 


--  APML Archives at <http://astro.umsystem.edu/apml/>  ---
             Unsubscribe at <majordomo@seds.org>