Oscar 13 re-entry

Russell Eberst (R.Eberst@roe.ac.uk)
Wed, 13 Dec 1995 18:11:03 +0000 (GMT)

Those of you interested in the re-entry of satellites from highly elliptical
orbits may like to review the re-entry of Explorer34 also known as IMP5 or
67-51A (All these off the top of my head). The lunar perturbations on this
object were such that, at the end, the penultimate orbit had a perigee height
of a few hundred kilometres, but the next revolution the perigee height was
close to the Earth's surface. The orbital period was something like 6000
minutes - about 4 days. With this kind of variation, air drag took very
little part in the decay stage, and it was possible to predict the final
plunge accurately in time and place, well in advance of it occurring.
I remember seeing (possibly in "Sky & Telescope") a diagram showing a short
path over the Indian Ocean, describing when and where to look.
It is possible that Oscar 13 will be similarly affected, and all that is
needed is to accurately model luni-solar perturbations.
best wishes  Russell