Prelaunch Thermal Anomaly and Thermal Testing of the Psyche Cold Gas Thrusters

The Psyche Mission launched successfully on October 13, 2023, but its launch was threatened by a significant Cold Gas Thruster (CGT) overheating concern. This late discovery required a very diligent and focused investigation that resulted in a comprehensive test campaign and analysis effort. Thermal vacuum testing for the Psyche Cold Gas Thrusters (CGTs) was successfully completed with 87 test runs over a 23-day period from September 15 through October 7, 2023. Testing was completed six days before launch. The test grew significantly in scope when it was discovered that the flight valves were in danger of overheating during operation. The maximum operational duty cycle for the flight valves had to be dropped from 80% to 30% to prevent overheating in flight. Final test results provided sufficient proof that the hottest flight unit coil would reach a steady state temperature of 140°C (the maximum recommended coil temperature) at a 30% duty cycle under worst-case hot flight conditions. This paper documents the test results from two Flight valves and one Engineering Model valve. Lessons learned from this testing are also presented.