Ten-Koh is a 23.5 kg, low-cost satellite developed to conduct space environment effects research in low-Earth orbit (LEO). Ten-Koh was developed primarily by students of the Kyushu Institute of Technology (Kyutech) and launched on 29 October 2018 on-board HII-A rocket F40, as a piggyback payload of JAXA’s Greenhouse gas Observing Satellite (GOSAT-2). The satellite carries a double Langmuir probe, CMOS-based particle detectors and a Liulin spectrometer as main payloads. This paper reviews the design of the mission, specifies the exact hardware used, and outlines the implementation and operation phases of the project. This work is intended as a reference that other aspiring satellite developers may use to increase their chances of success. Such a reference is expected to be particularly useful to other university teams, which will likely face the same challenges as the Ten-Koh team at Kyutech. Various on-orbit failures of the satellite are also discussed here in order to help avoid them in future small spacecraft. Applicability of small satellites to conduct space-weather research is also illustrated on the Ten-Koh example, which carried out simultaneous measurements with JAXA’s ARASE satellite.
As small satellites are becoming more widespread for new businesses and applications, the development time, failure rate and cost of the spacecraft must be reduced. One of the systems with the highest cost and the most frequent failure in the satellite is the Electrical Power System (EPS). One approach to achieve rapid development times while reducing the cost and failure rate is using scalable modules. We propose a solar module integrated converter (SMIC) and its verification process as a key component for power generation in EPS. SMIC integrates the solar array, its regulators and the telemetry acquisition unit. This paper details the design and verification process of the SMIC and presents the in-orbit results of 12 SMICs used in Ten-Koh satellite, which was developed in less than 1.5 years. The in-orbit data received since the launch reveal that solar module withstands not only the launching environment of H-IIA rocket but also more than 1500 orbits in LEO. The modular approach allowed the design, implementation and qualification of only one module, followed by manufacturing and integration of 12 subsequent flight units. The approach with the solar module can be followed in other components of the EPS such as battery and power regulators.
Satellites must endure the hostile environement during their launching to space via rocket; therefore, they should be exposed to the real launch conditions for ground testing, including all subsystems and components which should be carefully tested. Several solid-stateceramic batteries have been selected to be evaluated under the launch environment after been evaluated under the space environment, which has shown so far good results. This paper focuses on the physical degradation and the electrical performances of the batteries based on the discharge capacity, the open-circuit voltage, and charge/discharge modes. Batteries have been exposed to shock, then tested under vibration within different frequencies' levels with sinewave, sine burst, and random. Before and after the test, the physical properties of all batteries have been checked, several cycles of discharge and charge have been performed to check their performances and survivability after the evaluation test. With 95% of capacity, batteries could demonstrate their ability to withstand the launch conditions successfully, they could be able to operate during several cycles after the test, so far, showing no degradation on their performances within the limits. Also, the paper is providing the main requirements and criteria for batteries' launch ground testing for the small satellite project.
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