Astronomy, Doughnuts, and Carrying Capacity

I examine the applicability of ecological concepts in discussing issues related to space environmentalism. Terms such as "ecosystem"", "carrying capacity"", and "tipping point" are either ambiguous or well defined but not applicable to orbital space and its contents; using such terms uncritically may cause more confusion than enlightenment. On the other hand, it may well be fruitful to adopt the approach of the Planetary Boundaries Framework, defining trackable metrics that capture the damage to the space environment. I argue that the key metric is simply the number of Anthropogenic Space Objects (ASOs), rather than for example their reflectivity, which is currently doubling every 1.7 years; we are heading towards degree scale separation. Overcrowding of the sky is a problem astronomers and satellite operators have in common.
Comment: Seven pages, two figures. To be published in "Astronomy and Satellite Constellations: Pathways Forward", proceedings of IAU Symposium 385, eds. C.Walker, D.Turnshek, P.Grimley, D.Galadi-Enriquez, and M.Aube. For consistency with IAU policy, the version posted here is the submitted text under review