Check Valve Anomaly Investigation for the Mars 2020 Spacecraft

Following launch of the Mars 2020 spacecraft July 30, 2020, a fault response safely re-configured the operational pumps for the cruise heat rejection system as a result of a larger-than-expected system temperature gradient. Further analysis and investigation determined the cause to be a stuck-open check valve downstream of one of three pumps, allowing re-circulation through the pump itself and a reduced system flow rate. An in-flight characterization test confirmed the cause and cleared the check valve issue, returning the system to its as-designed flow rate. This investigation described here documents system thermal signatures with re-circulation, possible causes for the check valve issue, characterization results, and improvements for future missions.