The thermal control system fitted to satellites is responsible for managing the operating temperatures of all components during the satellite's life span. The extreme conditions in space pose a particular challenge in this respect. On the one hand, the ambient temperature in which a satellite operates may drop to absolute zero, while, on the other, temperatures may climb to extremes if it is exposed directly to the sun.
OHB develops various processes and technologies to address these problems:
- Computer-aided simulation of internal and external heat flows in the satellite during its intended orbit in space Use of the specialized software packages ESARAD and ESATAN.
- Definition on this basis of the necessary thermal control activities such as suitable thermal surface coating, design and positioning of insulation, heating system, active fluid-based cooling
- Development of dual-phase cooling circuits conducting heat through the vaporization and condensation of a fluid. For this purpose, heat pipe/loop heat pipes as well as mechanical pump systems are used
- Development of new materials with high thermal conducting properties and low thermal expansion
- Methods for integrating metallic thermal components in fiber-reinforced plastics (to allow for differences in thermal expansion)
Particular thermal requirements must especially be considered for exploration missions to the moon and Mars. Aspects which must be taken into account include the wide temperature differences between the sunny and dark side of some planets, the existence of a residual atmosphere (Mars 10 mbar CO2) and the reduced ability of solar cells to generate electricity. OHB is working on the following developments, among others:
- Thermal switch to deactivate the transfer of heat from the space vehicle in low-temperature ambient conditions
- Light powder-based insulation optimized for use in the residual atmosphere of planets
- Dual-phase mechanical pump systems for cooling circuits with long-life electric pumps
- Thermal generators to produce electricity from temperature differences in sun-remote applications