Developed an on satellite system for detecting, analyzing and mitigating cyber based threats. The goal is to deter cyber attacks on US space assets. In some cases, these attacks were orchestrated from ground station command and control operations. From the satellite’s perspective, command and control instructions from a hacked ground station are the largest threat to satellite systems.Our system consisst of the following components:.Threat detection and Reasoning componentoUtilizes stored normative behavior data to provide a framework for the detection of anomalous actions.oUses a probabilistic or possibilistic data fusion algorithm that accumulates evidence of atypical system behavior.oDetermines if current actions on-satellite fall outside the bounds of normal behavior.Uses the evidence available to determine a probability estimate for each satellite subsystem, which permits scaled differentiation of failure types..Counter-measures component. A decision-theoretic countermeasure scheme is activated to determine the most effective response to the satellite attack. Decision theory weights probabilities with costs associated with action or inaction to establish utility for each decision. The option providing maximum utility is selected.