A prototype lithium-ion battery with a bis(fluorosulfonyl)imide (FSI)-based ionic liquid electrolyte was developed. The prototype was mounted on a demonstration module of the "Hodoyoshi-3" microsatellite, which was successfully launched on June 20, 2014. Qualification tests for space application, including radiation tolerance and vacuum tests, revealed negligible degradation of the ionic liquid-based lithium-ion battery (IL-LIB) cell. According to the flight data, the IL-LIB cell can exist stably in an ultra-high vacuum environment despite its thin and flexible pouch casing without any rigid anti-vacuum reinforcements. Furthermore, the power unit showed the same charge-discharge performance as that predicted by the charge-discharge behavior of an identical cell on the ground, suggesting that the IL-LIB cell maintains performance in high vacuum a microgravity environment. These results prove that LIB cells with FSI-based ionic liquids can be used as a power source for space applications.

developed a twin micro-satellite: Hodoyoshi-3 and-4 to demonstrate and establish an innovative system design and a cost-effective development process for the mass production of micro-satellites in the future based on a new concept called "Hodoyoshi", which means "reasonably reliable". On June 19, 2014, the two satellites were successfully launched into Sun Synchronous Orbit, at an altitude of approximately 630 km. To date, we met several objectives with regard to system performance on-orbit, a considerable amount of mission data including Earth observation images. This project demonstrates system architecture design methods, integration and test processes, and on-orbit operation methods such as recovery functions from anomalies. The project is currently undergoing evaluation, under which the results of the operation are being reviewed with regard to the Hodoyoshi concept. This paper explains the Hodoyoshi concept, providing examples of hardware and software design, and arriving at a reasonable interface design and coordination. The paper also introduces the major characteristics of the satellites, and explains the key features and approaches of microsatellite development to realize cost-effectiveness.

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This paper summarizes two new satellite impact tests conducted in order to investigate on the outcome of low-and hyper-velocity impacts on two identical target satellites. The first experiment was performed at a low velocity of 1.5 km/s using a 40-gram aluminum alloy sphere, whereas the second experiment was performed at a hyper-velocity of 4.4 km/s using a 4-gram aluminum alloy sphere by two-stage light gas gun in Kyushu Institute of Technology. To date, approximately 1,500 fragments from each impact test have been collected for detailed analysis. Each piece was analyzed based on the method used in the NASA Standard Breakup Model 2000 revision. The detailed analysis will conclude: 1) the similarity in mass distribution of fragments between lowand hyper-velocity impacts encourages the development of a general-purpose distribution model applicable for a wide impact velocity range, and 2) the difference in area-to-mass ratio distribution between the impact experiments and the NASA standard breakup model suggests to describe the area-to-mass ratio by a bi-normal distribution.

This paper provides an overview of a low-cost small university satellite. In June 2006, JAXA announced a program for the selection of H-IIA piggyback passengers to small-satellite projects performed by universities and regional communities in Japan. In this context, we started the satellite project named QSAT (Kyushu Satellite) in 2006. The primary objectives of the QSAT mission are 1) to investigate plasma physics in the Earth's aurora zone in order to better understand spacecraft charging, and 2) to conduct a comparison of the field-aligned current observed in orbit with ground-based observations. QSAT has two payload instruments, two plasma probes and a novel magnetometer. The laboratory of Spacecraft Environment Interaction Engineering of Kyushu Institute of Technology has the responsibility of the development of plasma probes, whereas, the Space Environment Research Center of Kyushu University has the responsibility of the development of the new magnetometer. The spacecraft bus is being developed at the

This paper describes the development of store and forward (S&F) systems for Hodoyoshi-3&4 satellites and their in-orbit operation results. In this study, ultra-high frequency receivers are installed on Hodoyoshi-3&4 and are used for S&F. The S&F systems collect data from ground sensors, store the received data into the satellite on-board storage, and then transmit the stored data to the main ground station using an X-band transmitter. S&F are effective and useful systems for collecting data from the ground where ground-based communication systems are not available. This paper reports in-orbit S&F technical experiments performed in the Hodoyoshi-3&4 missions, demonstrating that the use of ground signal processing improved the signal demodulation rate by a factor of 3.6. These experiments show that S&F system can be utilized in small-size satellites that have strong limitations of mass, space, and power consumption. Based on the test results, this study concludes that the proposed systems can be applied to a variety of objectives applications involving nanosatellites and microsatellites.

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