  As the space industry approaches a period of rapid change, securing both
emerging and legacy satellite missions will become vital. However, space
technology has been largely overlooked by the systems security community. This
systematization of knowledge paper seeks to understand why this is the case and
to offer a starting point for technical security researchers seeking impactful
contributions beyond the Earth's mesosphere.
  The paper begins with a cross-disciplinary synthesis of relevant threat
models from a diverse array of fields, ranging from legal and policy studies to
aerospace engineering. This is presented as a "threat matrix toolbox" which
security researchers may leverage to motivate technical research into given
attack vectors and defenses. We subsequently apply this model to an original
chronology of more than 100 significant satellite hacking incidents spanning
the previous 60 years. Together, these are used to assess the state-of-the-art
in satellite security across four sub-domains: satellite radio-link security,
space hardware security, ground station security, and operational/mission
security. In each area, we note significant findings and unresolved questions
lingering in other disciplines which the systems security community is aptly
poised to tackle. By consolidating this research, we present the case that
satellite systems security researchers can build on strong, but disparate,
academic foundations and rise to meet an urgent need for future space missions.
