Practical Considerations of Integrating a Passive Thermal Control System onto Small-Satellites - The Ten-Koh Case Study
Fajardo Tapia, Isai
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The research detailed in this paper aims to address the problem of thermal management of small-satellite (particularly micro and nano-satellite) platforms by proposing a passive Thermal Management System (TMS) that can be integrated onto existing satellite designs. This characteristic will be highlighted through discussion of the work undertaken to integrate elements of the TMS onto the recently launched Ten-Koh micro-satellite. This integration was conducted to allow an on-orbit demonstration of the passive switch component where a highly dissipating payload is used as the heat source. The TMS is comprised of three key components. These include a heat strap manufactured from Pyrolitic Graphite Sheet (PGS), a thermal switch activated by Shape Memory Alloy (SMA) and a multi-layered PGS radiator, folded to provide maximum radiative surface area once deployed from an external face of the small-satellite. Breadboard testing of the PGS strap and SMA switch has been conducted, the results of which were presented at ICES 2017 . This testing characterised heat transfer through the PGS as a function of strap thickness and interface pressure. It also showed that, while the prototype SMA switch generated sufficient interface pressure to allow good heat transfer through the strap, further development was required to improve reliability. Since ICES 2017, significant development of the switch has been undertaken to allow successful integration onto the Engineering and Flight Models of the Ten-Koh recently launched by JAXA. Specifically, an intensive development period was undertaken to ensure that the switch was sufficiently robust to pass all of the JAXA safety and qualification tests prior to launch. This included shock, vibration and system-safety testing. Additional integration work was also carried out to ensure that the pressure and temperature sensors which will provide telemetry data on-orbit, successfully integrated with the satellite's on board computer.