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Research for Secure Development and Success of Missions Advancement of basic technologies on mechanisms and materials for expanding space activities Health maintenance and life extension under extreme temperatures

It is essential to establish technology for driving equipment that can operate in a wide range of temperatures if space activities are to be expanded. Solid lubricants must be used below -70°C, where space-proven oils and greases cannot be used. However, it is difficult to extend service life with solid lubrication, especially for reduction gears, which are important in rovers and robots. There are few examples of its use. Although research is being conducted outside Japan, no one has yet to fully satisfy the service life requirements, and extending service life in extremely low-temperature environments remains challenging.

This research focuses on a new solid-lubricated reduction gear for space applications that can satisfy long-life requirements under extreme temperatures (-200°C or lower).

Advancement of basic technologies on mechanisms and materials for expanding space activities

An example of research results

Lubrication under extreme temperatures can significantly affect the performance and life of the reducer due to changes in the temperature distribution in the reducer complicated by internal heat generated by sliding and heat flow in and out of the reducer. We have developed the prototype speed reducer shown in Figure 1 by optimizing the lubrication design to match these thermal changes and individual sliding configurations.

Figure 1: The reduction gear

The test equipment also had developmental elements and was designed and fabricated with consideration of thermal effects so that the performance of the reducer could be evaluated. Figure 2 shows the test apparatus, and Figure 3 shows the inside of the vacuum chamber. Currently, a vacuum chamber is used to simulate the space environment. The performance and operating life of the reducer are being evaluated in a vacuum and at extreme temperatures (-200°C or lower).

Figure 2: Test equipment
Figure 3: Inside the vacuum chamber
Advancement of basic technologies on mechanisms and materials for expanding space activities