@ofnumbers in a sense, only SpaceX has survived. the others exist, but they’ve not seemed to have succeeded. 1/

@ofnumbers they all — including NASA — face soft budget constraints, due to some mix of plutocratic support and state subsidy. SpaceX has those too, but whether it’s “profitable” or not, it’s clear SpaceX has been a justified use of the resources it’s required, while the others arguably have not (for NASA, arguably have not recently, though JWST is perhaps humanity’s most extraordinary accomplishment even if it went way over budget). 2/

@ofnumbers institutional survivorship is not much of a measure of success in the sector, i think. nor is a public/private distinction very informative. /fin