It was proposed to install an RTP device on the Venus explorer PLANET-C. In fact, we manufactured a model with modified structure to install on the explorer, and tested and evaluated it. First, we carried out evaluation tests of fin deployment and retraction by changing temperature in the atmospheric pressure (Fig. 4a). Next we performed a thermal-vacuum test to simulate the space environment. The test results indicated that autonomous heat-radiation change occurred in response to temperature change (Fig. 4b). Thus, an unprecedented device was created, one that is lighter than ever before and excellent in heat-release performance while having heat-retention and sunlight heat-absorption functions. Further, we performed a launch-environment resistance test and verified that the device can endure the rocket launch. Next, a trade study was conducted as adaptation research for PLANET-C (Fig. 4c). Assuming a certain mission equipment, we compared two thermal control methods, i.e., one by using the conventional heat-radiation planes/heaters and another by using the RTP. As a result, it became clear that the RTP can reduce electric power requirements for mission equipment heaters at cold temperatures by more than 90%. Unfortunately, due to the tight schedule, the RTP will not be installed on the explorer. Nevertheless, we are sure that demand for the RTP will increase for such missions as PLANET-C, which will be exposed to large thermal-change environments. We expect such future space science missions to introduce the device.
Thermal control is a mundane, humble task but plays an extremely important role in the success of high-level missions. In particular, we must pursue optimal design for future missions because high-density packaging, high-added value and light weight, and energy savings are required simultaneously. In the course of seeking the perfect design, the last problem we face is the thermal issue.EMoreover, in both Japan and overseas, most spacecraft troubles are, either directly or indirectly, closely related to the heat problem.EIt must be key for the success of future missions that how we advance thermal design and how we incorporate advanced thermal-element technology underlying the next-generation designs.
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