A passive delployable/stowable radiator named reversible thermal panel (RTP) has been developed for thermal control of interplanetary spacecrafts. The RTP can autonomously adapt to a wide variety of thermal environments with no electrical power. An RTF prototype model (PM) was fabricated and extensive test programs including fin deployment/stowing tests, thermal performance tests, and vibration tests have been executed to validate that the RTP-PM can meet all the qualification requirements. Deployment/stowing tests have demonstrated repeatable RTF fins deploy/stow from 0° to 140° over the temperature range from -30°C to +30°C. Thermal performance tests including thermal balance tests and power cycling tests have shown RTF's autonomous thermal control for changes in thermal conditions. The RTF has also been subjected to qualification-level vibration loads and passed with no significant issues.