Updating the inventory of spacecraft reentries: challenges and limitations

A crucial input to the scientific study of anthropgenic effects on the upper
atmosphere is a reliable inventory of reentering objects. Some studies
have relied on the US Space Force catalog as a finding list for reentries,
but it is severely incomplete as it does not include objects which stay in
space for less than a few orbits. The General Catalog of Space Objects
(planet4589.org) includes an `auxiliary catalog' which adds these missing
objects, mostly launch vehicle upper stages. For the past three years
the catalog has been enhanced to include approximate reentry locations,
mostly based on NOTAM and similar warning area notifications, permitting
a spatially dependent assesment of the input reentry flux; the study
by Barker, Marais and McDowell (2024) has made use of this data.
I will discuss some features of the catalog as well as its limitations.