In 2002 Qnergy engineers (at the time known as Stirling Technology Company) teamed up with NASA on a power source for deep space exploration. In July 2018 NASA reported that it had been working for more than twelve years maintenance-free calling it the most reliable heat engine in “the history of civilization.” NASA issued an update recently and the engine is still running seamlessly, 14 years later! It keeps running and running!
Stirling Convertor Sets 14-Year Continuous Operation Milestone