RE: Milstar/Centaur?
Ted Molczan (molczan@home.com)
Tue, 4 May 1999 11:34:18 -0400
I have yet to contact the Namibian observer(s), but the one huge problem
with the cloud they sighted, is that it was stationary for 20 minutes, which
is way too slow to have been the errant Milstar, in its final 741 km x 5000
km orbit.
Otherwise, the time of the sighting (19 h UTC) has some consistency with the
Milstar launch, because that is the published approximate time of the
separation of the Milstar from the Centaur. That would seem to have been a
logical time for the Centaur to have vented unburned propellant.
It is my understanding that three faulty Centaur burns occurred within a 90
minute period, which I believe would have ended about 50 minutes before the
Namibian sighting at 19 h UTC, so a venting seems more likely than a burn.
The low orbit of the Milstar, suggests that little of the Centaur's
propellant had been burned (unless the burn was significantly out of plane,
which is quite possible), so there may have been more propellant than usual
to vent. (It could also have made a dandy explosion.)
It is possible to construct an orbit consistent with the initial time and
position of the Namibian sighting, and the published Milstar launch time,
launch azimuth, and final orbital dimensions (741 km x 5000 km):
USA 143 guess 15.0 4.5 4.5 3.8 d
1 25724U 99023 A 99120.79166667 .00000000 00000-0 00000-0 0 05
2 25724 28.6940 291.3500 2304280 0.0000 220.0000 9.77213000 03
To produce the above, I assumed the observer was near Windhoek, Namibia, and
observed the cloud at about RA 7:20h and Dec 0.0 deg, at 19 h UTC.
Clearly, this orbit is very rough - and not just because I don't know the
exact location of the observer. For example, the argument of perigee is
zero - the default value in my software - which just happened to fit. But
there is likely a range of arguments of perigee that would fit. Moreover,
since the Centaur was out of control, there is no reason to believe that its
burns were coplanar, so the inclination likely is much different than the
one suggested by the launch azimuth.
The story is interesting and has some possibilities, but as long as the
cloud did not move, then I do not recommend that anyone waste time trying to
search on the above elements. Lets see what additional information emerges.
Ted Molczan