RE: Pre-solstice spysat launches: why?

Ted Molczan (
Mon, 30 Dec 1996 03:12:33 -0500

Allen Thomson asked:

>   Why,  for the past decade, has the US launched its 
>sunsynchronous spysats in the month before the winter solstice? 

Well, not all were launched one month before
the solstice: 87090A was launched on 26 Oct 
and 88099A was launched on 6 Nov. I recommend 
that we also include the failed Kh-9 launch of 
Apr'96. (It was believed to have been a 
replacement for the failed Kh-11 launch of 
28 Aug 1985.)

   In discussions concerning this, some general explanations have 
been offered, to wit,

>1) There is some technical reason, probably related to solar 
>   illumination of the targets on the ground or the solar panels on 
>   the spacecraft that makes pre-solstice launch desirable.

 Always a good hunch, but difficult to prove.

>2) Pre-solstice launch prevents northern-hemisphere optical 
> observation(**) of the payload during deployment and for two or
> three months thereafter.  There is a paucity of known optical 
> observers in the southern hemisphere, and anyway the 
> distribution of land and population down there mitigates 
>  against spotting satellites launched in November and 
>  December.  

I have never believed that military space 
operations planning includes considerations
of amateur observers abilities. There are
too many other more important variables
constraining missions without adding us 
into the mix.

>   But what's the point?  One would presume the USSR (now Russia) and 
>   possibly other countries have been following the payloads with radar, 
>   and maybe with daylight visual/IR methods from launch onward.  In any 
>   event,  the launch timing, azimuth and booster configuration, along 
>   with  observation of the payloads of previous similar launches let 
>   the orbits be inferred quite nicely, as evinced by amateur observers' 
>   success in finding and identifying the satellites when they become 
>   visible in March and April.

I agree, there is no point based on denial of

>   One slightly paranoid suggestion that's been made to resolve 
>   this puzzle is that there are actually two payloads on the 
>   boosters (Titan-IVs with oversize payload shrouds), 

As far as I know since the Kh-9 program which 
began in 1971, the payload has been about 15 m long,
requiring a 17 m shroud. I have never heard of an
over-size shroud used for a Kh-9 or Kh-11, but
I do not have proof of that.

>of course, there's always
>3) There's nothing to explain. The pattern didn't exist before about ten 
>   years ago, not that many satellites have flown subsequently,  
>   and the pre-solstice "pattern" is most likely a fluke of small-
>   sample statistics.

I like that explanation the best.

Ted Molczan