This paper describes the validation process for the Autonomous Sciencecraft Experiment, a software agent currently flying onboard NASA’s EO-1 spacecraft. The agent autonomously collects, analyzes, and reacts to onboard science data. The agent has been designed using a layered architectural approach with specific redundant safeguards to reduce the risk of agent malfunction to the EO-1 spacecraft. This “safe” design has been thoroughly validated by informal validation methods supplemented by sub-system and system-level testing. This paper describes the analysis used to define agent safety, elements of the design that increase the safety of the agent, and the process used to validate agent safety.