  From the moment astronomical observations are made the resulting data
products begin to grow stale. Even if perfect binary copies are preserved
through repeated timely migration to more robust storage media, data standards
evolve and new tools are created that require different kinds of data or
metadata. The expectations of the astronomical community change even if the
data do not. We discuss data engineering to mitigate the ensuing risks with
examples from a recent project to refactor seven million archival images to new
standards of nomenclature, metadata, format, and compression.
