The Thermal Canister is a proof of concept experiment flown on the third flight of the Space Shuttle (March 1982). The canister utilizes heat pipe technology to provide a closely controlled, stable temperature environment for scientific instruments negating the effects of the harsh, variable shuttle environment. Primary objectives were to demonstrate control at 15° ± 2°C in each of the four external environments experienced by the shuttle. Secondary objectives were to control different side panels of the canister simultaneously to different temperatures in the 5° to 25°C range. The canister met all flight objectives.