Postprint version. Published in Science & Global Security, Volume 1, Issue 1 & 2, January 1, 1989, pages 109-128.
The definitive version is available at https://doi.org/10.1080/08929888908426326.
This paper assesses the level of confidence for monitoring a ban on nuclear power in earth orbit using unclassified information from astronomical observatories based on Maui, Hawaii, and from the Kuiper Airborne Observatory. It is concluded that existing military and astronomical observatories can detect and identify operating nuclear reactor sources, such as the Soviet RORSAT and US SP-100, on satellites with a very high level of confidence out to distances beyond geosynchronous orbit. The smaller radioisotope thermal sources, RTG and DIPS, could be detected with a medium level of confidence under certain conditions.