  Astronomy, as a field, has long encouraged the development of free, open
digital infrastructure (e.g., National Research Council 2010, 2011). Examples
range from simple scripts that enable individual scientific research, through
software instruments for entire communities, to data reduction pipelines for
telescope operations at national facilities. As with the digital infrastructure
of our larger society today (e.g., Eghbal 2016), nearly all astronomical
research relies on free, open source software (FOSS) written and maintained by
a small number of developers. And like the physical infrastructure of roads or
bridges, digital infrastructure needs regular upkeep and maintenance (e.g.,
Eghbal 2016). In astronomy, financial support for maintaining existing digital
infrastructure is generally much harder to secure than funding for developing
new digital infrastructures that promise new science. Sustaining astronomy's
digital infrastructure is a new topic for many, the sustainability challenges
are not always widely known...
