  Astrophysics is a social enterprise exemplified here by the Dark Energy
Survey (DES) which completed its fieldwork in 2019 after 16 years of
preparation and observation, while data analysis continues. Society funds
astrophysics on a grand scale. For human capital and for governance the
discipline draws on a self-governing "republic of science", while the funds
were provided by philanthropists in the past, and by governments today. The
benefits accrue initially to scientists themselves, in the form of a rewarding
vocation. For the social benefit it is tempting to apply formal cost benefit
analysis, but that approach ignores the option value of science and imposes
questionable assumptions from welfare economics. Astrophysics generates some
useful spinoffs, offers attractive careers, appeals to the popular imagination,
speaks to metaphysical cravings and constitutes a good in itself. The rise of
AI also suggests a role in exploring future habitats for intelligence and
cognition.
