Thermophysical properties of high thermal conductivity graphite sheet for spacecraft thermal design

In order to apply a new material - graphite sheet, which is characteristics of high thermal conductivity, lightweight and flexibility, to the material for spacecraft thermal control applications, following thermophysical properties of this material have been measured: (1) The thermal diffusivities in the in-plane direction and the out-of-plane direction were measured over the temperature range from 100 to 350 K by using a laser heating ac calorimetric method. (2) The specific heat and the total hemispherical emittance were measured over the temperature range from 173 to 375 K by using a transient calorimetric method. (3) The solar absorptance was measured by using a spectroscopic method for angles of incidence ranging from 5° to 60°. Additionally, the thermal conductivities and the specific thermal conductivities were calculated using the measured result, and high potentials of this graphite sheet as a material for the spacecraft thermal control were confirmed.