Satellite/Laser : a compilation

Bart De Pontieu (BDP@MPE.MPE-GARCHING.MPG.DE)
Mon, 23 Jan 1995 18:00:27 +0100 (CET)

A compilation of the reactions I've received so far on this weird
observation. Thanks to all who contributed.

Mike McCants wrote about his own experiences :

>One time when I was at McDonald Observatory I saw their laser ranging
>to one of the Lageos satellites.  They are quite high (3000 miles)
>and would move fairly slowly.  But, 1) the laser beam was obviously
>pulsing, and 2) it was obviously colored green.  The laser did
>not cause the satellite to shine at a visible magnitude at a range
>of 3000 miles - that would require a lot of power!
 
[BDP : No Lageos satellites visible in the half hour period that match
the orbit even remotely.]

Greg Retzlaff :

>When it is cold, there can be ice crystals in the air, that may have been 
>what he saw, the light from the (bright) satellite reflecting from the ice 
>crystals in the air.  I would have to think about it to convince myself that 
>the "beam" would go to a constant place on the horizon.
>More importantly, did the beam disappear at the same time the satellite did??
>If it was a real beam originating from the satellite, it would be independent
>of whether the satellite was in sun or shade.  If it was an artifact
>of the light after reflection from the object it would disappear at
>the same time as the satellite. 

[BDP : The map I received shows the beam is really long, spanning several
tens of degrees. It also changes direction all the time. The beam really
'originates' from one point at the horizon. It seems the point at the
horizon does *not* coincide with the Observatoire de l'Haute Provence, where
lasers are used to measure the ozone layer (but not for satellites, as far
as I know). So far nothing is known about whether the beam switched off
simultaneously with the satellite's disappearance or not. The satellite was
lost out of sight because of a building obstructing the view]

Mike McCants reports a possible orbit :

>1 99999U          94363.18908607 0.00000060  00000-0  12308-7 0    09
>2 99999  60.0000 143.6090 0000010 125.8900 234.1077 16.30000000    06

>This crazy elset comes kind of close to fitting the obs.
>(I did change the -3 dec to a +3.)
>This is a really low orbit.

Rob Preston aks :

>is there a reason to rule out laser FROM the satellite TO the ground?
>(maybe there's military classified lasers up there, US or russian, being
>tested against terrestrial retroreflectors in some embassy's backyard?

[BDP : There's no reason for ruling that out. The observer actually leavs
open both possibilities -contrary to my orginal second-hand report.

Allen Thomson suggests :

>The French are setting up their own space surveillance system to keep
>track of the spy satellites of Certain Foreign Countries; see the
>article on the GRAVES radar in the September 29, 1994 issue of Air et
>Cosmos. Possibly what you saw was related to, for example, active
>optics imaging of such a satellite. Just a speculation.

[BDP : Maybe it wasn't a satellite at all, but in the vein of what Allen
suggests, an experiment where a laser for active optics imaging (of
whatever not necessarily of satellites) is 'sweeped' rapidly over the
sky. The bright 'dot' at the end (of mag 1, i.e. brighter than the beam
itself) would then be where most of the beam's light is reflected? I
seem to remember images in Sky and Telescope where one could see the
region of reflection of such a laser as a local brightening?]

Rainer finally reports on his calculations :

>>The object disappeared in Ursa Major, maybe due to the entry into the 
>>shadow or due to a high building obscuring it. 
>The positions give a direction of motion towards Hercules/Lyra (not UMa). 
>If the object was last seen in UMa, then it was not a satellite (possibly 
>an airplane). 
 
The map I received shows the last point as the last point seen. I think the
'Uma direction' reference should not be taken literally, but more as a
general direction. The last point is not too far from eta Ursae Majoris.

>UNK941229LA    
>1 99000U          94363.09739082  .00000000  00000-0  00000+0 0    03 
>2 99000  63.3000 149.3725 7600031  27.7400 289.2765  2.00600000    07 
>                          calc.            obs. 
> 1 363  4 45 15.0    .0 13 49.2 -2.81  13 50.0 -3.00   .20  -.19   .28  49 
> 1 363  4 45 30.0    .0 14 58.9 13.32  15   .0 13.00   .28  -.32   .42  51 
> 1 363  4 45 45.0   -.1 16  2.2 25.31  16   .0 26.00  -.51   .69   .86  52 

I'm pretty sure the positions have an accuracy that is of the order
'several degrees'. 

So it would seem Rainer's second orbit is just as probable :
  
>UNK941229LA    
>1 99000U          94363.09739082  .00000000  00000-0  00000+0 0    03 
>2 99000  63.3000 149.2369 7512911  46.8005 287.5648  2.00600000    03 
> 1 363  4 45   .0    .8 12 28.9-13.30  12 20.0-10.00 -2.21  3.30  3.97  48 
> 1 363  4 45 15.0   -.5 13 40.6   .17  13 50.0 -3.00  2.36 -3.17  3.95  49 
> 1 363  4 45 30.0   -.3 14 56.6 14.13  15   .0 13.00   .82 -1.13  1.40  51 
> 1 363  4 45 45.0    .9 16  4.8 24.14  16   .0 26.00 -1.09  1.86  2.16  52 
 
But are there any objects in this type of orbit? Active payloads?
 
Cheers,
   Bart