## 2 Materials and Methods: Ten-Koh Mission Description
### Satellite Concept of Operations  
For all experiments and mission objectives, the concept of operations is shown in Figure 7. There is one main ground station (MGS) located at Kyutech, from where all missions are planned and executed, and housekeeping and payload data are downlinked. The mission was defined to start operations in a period of 2-3 weeks after the launch by following the next sequence of events:  
1. Launch on 29 October 2018 at 13:10 Japan Standard Time (04:10 UTC) from the Tangeashima Space Center in Japan, onboard the H-2A rocket number F40 as a piggyback payload of the GOSAT-2 satellite. 2. Separation from the rocket 2000 s after liftoff at an altitude of 623 km and with an orbital velocity of 7.5 km/s. The preliminary orbit was estimated to plan tracking of the satellite during the first hours after separation, until a more precise ephemeris was obtained later: semi-major axis of 6969.772 km; eccentricity of 0.002586; inclination of 97.835 deg; argument of perigee of 27.546 deg; longitude of the ascending node of 313.285 deg; and true anomaly of 212.990 deg. All data were provided by the Japan Aerospace Exploration Agency (JAXA) prior to the launch [22]. Nominal operations were carried out using Two Line Element sets (TLEs), as customary for small satellites. 3. After the separation and orbit insertion, and once all systems onboard were verified, the mission operations started on 19 November 2018. 4. During each communication session with the main ground station located in Kyutech, housekeeping telemetry and mission data are downlinked and missions are executed according to a previous plan (see the following process of mission planning and execution in Steps A-D). \begin{table}
\begin{tabular}{l l l} \hline \hline
**Item** & **Instrument/Sensor** & **Measurement Range** \\ \hline \multirow{3}{*}{\begin{tabular}{l} Charged particle detector \\ based on CMOS sensors \\ \end{tabular} } & 6 detectors for protons, electrons and ions. & The final range will be defined based on ground calibration and orbital data. \\  & 2 x-ray detectors & Dose rate [Gy/h]: 1.12 \(\times\) 10\({}^{-8}\) to 0.188 \\  & & Flux [particles/cm\({}^{2}\)/s]: 0.01–10,000 \\  & & Deposited Energy [MeV]: 0.081–20.833 \\ \multirow{3}{*}{\begin{tabular}{l} Material mission \\ Temperature measurements \\ \end{tabular} } & Strain measurements & Strain: 10,000 \(\times\) 10\({}^{-6}\) to 1 \(\times\) 10\({}^{-6}\) \\  & & Temperature [C]: – 55–150 \\ \multirow{3}{*}{\
\begin{tabular}{l} DLP \\ \end{tabular} } & Electron & Current [A]: +/\(-\) 10 \(\times\) 10\({}^{-6}\) \\  & & Minimum current [A]: 80 \(\times\) 10\({}^{-12}\) \\ \multirow{3}{*}{
\begin{tabular}{l} Magnetic field measurements \\ sensor \\ \end{tabular} } & Magnetometer based on 3-axis magnetoresistive & Voltage [V]: +/\(-\) 11 \\  & & \\ \cline{1-1}  & & \(+/-\) 2 \(\times\) 10\({}^{-4}\) [T] \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Main payload instruments. Based on the above key events, the mission operation phases given in Table 2 have been defined. Each phase refers to a section of the life cycle of Ten-Koh satellite, which itself starts with the launch and lasts until the decommissioning of the mission. The process of performing all missions on-board Ten-Koh (Processes 3 and 4 in the concept of operations above) is as follows:  
Figure 6: The payload arrangement onboard the spacecraft: external arrangement (**a**); internal arrangement (**b**,**c**); and internal structure dimensions in millimeters (**d**). An experiment is planned to be executed in a selected position and epoch along the orbit with a specified time duration. * A set of uplink commands is configured and scheduled for commanding the satellite in a selected pass over the MGS in Japan. * During the designated pass for operations, the satellite health status is confirmed first by housekeeping telemetry. Then, the uplink command is received by the satellite and the OBC configures the payload instruments and the required subsystems to provide the resources for the mission to be executed.