There was a time when Electric Propulsion (EP) was so new that there were no test facilities for it. The Electric Propulsion Space Experiment (ESEX) promised to bring ArcJet technology into the real world by flying it on the Adv. Research and Global Observation Satellite (ARGOS) spacecraft. Capt. Salvador Castillo was assigned to build a facility from scratch to test high power ArcJets in a vacuum. The facility did the initial testing of a brand new 30kW ammonia ArcJet with 2 Newtons (~0.5 lbf) of thrust. ESEX was the first High Power Electric Propulsion flight, the largest power subsystem flown at the time and the first use of steady-state EP. The ESEX was put through its paces including checkout testing, flight qualification testing and experiment integration. It was then handed over to the lab’s Spacecraft and Launch Integration Team in 1996.