Decay of Cosmos 398

Rainer Kracht (R.Kracht@t-online.de)
Mon, 18 Dec 95 22:49 +0100

Decay of Cosmos 398

I have received several comments regarding the decay time of Cosmos 398.

Pierre Neirinck wrote:

> 1. NORAD ndot/2 before decay are always lower than actual ndot/2.
> 2. Most decays I saw were southbound and shortly after perigee.
> 3. The perigee being omega = 36, decay times would be 17:20 (ruled out)
>                                                       18:45 (possible)
>                                                     <=20:10 (probable)
> 4. h being < 123 km at 17 h, TrakSat h is irrealistic.

With a decay 2100 km SE of Hawaii 18:45 is ruled out too.

The final elset has an orbit of 124 x 157 km with epoch 16:41 UTC and
produced a groundtrack which was 2100 km ESE of Hawaii at 20:15 UTC.
With an actual ndot/2 greater than given with the this elset Cosmos 398
has reached the impact point somewhat earlier but with nearly the same
groundtrack.