A method for on-orbit calibration of the temperature sensors of a simulated blackbody is disclosed. The method may include selecting a simulated blackbody traveling in a micro-gravity environment and comprising a sensor, a container positioned proximate the senor and containing a material, and a heat transfer device positioned proximate the at least one container. The heat transfer device may transition the material through a phase change. The temperature sensor may monitor the temperature of the material during the phase change. A correction may be calculated to correct any disparity between the temperature reported by the temperature sensor during the phase change and the known plateau temperature corresponding to that phase change. The correction may be applied to subsequent temperature readings obtained using the temperature sensor.