Tumbling Lacrosse - was Re: Unidentified Bright Tumbling Satellite

Philip Chien (kc4yer@amsat.org)
Sun, 1 Sep 1996 19:02:57 -0400

Clement Drolet <76266.2530@compuserve.com> commented:

>I saw Lacrosse 1 flashing with a period
> of about 7.4 sec. C2322r came a little bit later at 21h06 with it's usual
> 2.0 sec period.
> Is this Lacrosse 1 flashing related to a tumbling, I've observed this
> satellite many times in the past and this is the first time I notice some
> flashing (the pass was almost at zenith).

Lacrosse 1 is (was?) a three-axis stabilized satellite, so there's no
reason it should be observed to be tumbling, spinning, or otherwise making
significant changes in appearance.  Certainly a three-axis bird can appear
to glint (vis Hubble), but should have a normally stable appearance.

The steady appearance of Lacrosse was one of the key factors which proved
that Sean Sullivan and myself were correct about the identity of the DoD-1
STS-53 shuttle payload, and also lead to the proper identification of USA
40.  It also showed that the media sound-byte artists without enough
technical background to understand what a launch window and change in
precession means were wrong when they claimed that DoD-1 was a Lacrosse or
that USA 40 was a KH-12 (sic) bird, but that's besides the point ....

Since Lacrosse 1 was launched in 1988 it's a fairly old satellite now,
certainly one of the oldest DoD LEO satellites in orbit.

My speculation - and this is purely speculation - is that Lacrosse 1 has
reached the end of its operational lifetime.  Either enough attitude
control components have failed so its out of control, or the controllers
shut the satellite off, letting it drift off axis to eventually die.

Normally you'd expect such a dark payload to be purposely deorbited at the
end of its useful lifetime (e.g. KH series) but there are a couple of
reasons why that might not have been done in this case:
  A technical problem with the attitude control system which would prevent
a controlled reentry
  An on-purpose save a bit of fuel and let the satellite go 'dead', with
the potential to recover the satellite in the future if necessary (not
likely, but certainly a possibility)
  The high altitude and stable orbit of the satellite would result in a
natural decay so far in the future that anybody who could recover anything
after reentry would just get a bunch of burned antique supercomputers and
other out-dated components.
  Less paranoia at the NRO (heck, they even have a Web site now!) and less
of a desire to use up a portion of a spacecraft's useful lifetime just to
ensure a controlled reentry.

Philip Chien, Earth News - space writer and consultant  PCHIEN@IDS.NET
   __                                 __^__          __________
  |   \                          +---/     \---+    (=========
  |____\___________              +---\_____/---+     //
  >____)|        | \__                    \  \______//___
 >/     |________|    \                   [         _____\
 >|____________________\                   \_______/
 Roger, go at throttle up         CHR$(32) the final frontier