AMPTE/IRM-1 decayed

Tue, 20 Feb 1996 15:14:17 +0100 (CET)

Thanks to all who have replied on SeeSat and in private mail to my
questions about AMPTE and archived orbital elements.

Allen Thompson and Tristan Cools are right when they say:

>   Objects in such highly elliptical orbits typically 
>experience strong lunar/solar perturbations which cause the 
>perigee to fluctuate significantly.  I'd guess IRM is long dead, 
>despite the "95165" epoch in the third element set.

Mike McCants brought message 436 of SeeSat-L to my attention 
in which the late Joel Runes announces his discovery that Spacecom
had apparently 'updated' orbital elements of several (high) satellites
by just changing the epoch date from 1985 to 1995.

Mike found that the September 1993 issue of the SSR gives 113808 
as apogee (instead of 13808). They just dropped the 100000 digit...

Mike also ran his lunar/solar perturbation program which gives a negative 
perigee in late 1987. This agrees very well with the RAE-estimate (Nov 1987
as reported by Tristan) and the 'Winter 1987' which was mentioned by the 
source of my friend at MPE.

Finally, Bill Wilkinson of Applied Physics Lab (APL) sent me a private

>AMPTE was a three part satellite that separated on orbit and flew in
>formation. MPE built one piece, the UK built another and APL in the US built
>the third. It was launched on 16 Aug. 1984. Check the homepage at 
>  The S/C is shutdown and the two european
>parts were last in the same lower orbit, while the US module is somewhat
>higher. The MPE module  had a larger drag coefficient which means it probably
>was the first come down. However the UK module shouldn't be far behind. The
>US module will probably stay up longer.   Could it be that one or more of the
>modules are still in orbit and there fore still being listed?

Maybe the US module is still in orbit?

    Bart De Pontieu <>