A Thermal Concept Minimizing the Heating Power Budget of a Planet Exploration Spacecraft 2003-01-2582
Electrical power savings are recurrent design drivers for Solar system exploration spacecraft. This is particularly applicable to the French mission “Mars Orbiter 2007” which consists in sending four Martian probes, after a one year cruise and before orbiting three years around the red planet.
Thus, a huge effort shall be made to minimize this spacecraft heating power demand. This challenge is less to limit the heating power inside the vehicle, for which proven systems exist, than to lower the heating power demand of the outer elements. Indeed, these external units, mainly chemical propulsion thrusters, potentially require a heating power reaching nearly 10% of the spacecraft electrical budget.
Consequently, the concept chosen to match the power optimization target consists in maintaining the spacecraft body temperature around 25°C thanks to a classical VCHP network itself regulated by a closed-loop control of the non condensable gas tank temperatures. Then, the upcoming idea is to use the warm cover constituted by the mechanical structure to warm up these external units.
So as to reach this aim, the outer elements like thrusters are thermally connected to the spacecraft frame thanks to thin and flexible stainless steel heat-pipes in order to transfer the sufficient heat and maintain them in the adequate temperature range.
Finally, in spite of mechanical and on-ground thermal test induced constraints, this solution leads to important savings in terms of heater line number and heating power budget without increasing vehicle mass.