## 2 Materials and Methods: Ten-Koh Mission Description
### Challenges Faced during the Project
#### 2.7.2 Available Space Location, Mass and Structure Interface for Some Payload Instruments  
The payload instruments were located in the upper half of the satellite in order to provide an unobstructed view for the CPD particle detectors, expose the material samples to the space environment, and allow CPD and DLP to be controlled by the same ECU, thus allowing synchronized measurements. Initially, controlling the GNSS receiver and the magnetometer from the same microcontroller was foreseen but was eventually found unfeasible due to PIC16F877 hardware limitations. However, these payloads were kept in their original locations to avoid large configuration changes late-on in the project. Only the microcontroller responsible for these two instruments was changed. \begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline \multicolumn{2}{p{113.8 pt}}{**Challenge and Its Origin**} & \multicolumn{1}{p{113.8 pt}}{**Solution**} \\ \hline a & _Challenge:_ Available generated power & Maximized solar array area + payload operations with reduced time duration. \\ \hline b & _Challenge:_ Available space location, mass and structure interface for some payload instruments & Platform subsystems were compactly accommodated at the bottom of the central internal structure and the inside walls of the external structure to maximize payload space. \\ _Origin:_ SmallSat constraint & _Origin:_ SmallSat constraint & Structure effects on the measured data need to be corrected for during result interpretation. \\ \hline c & _Challenge:_ Amount of data generated by the mission instruments & On-board storage capacity of up to 2 GB for the main payload instruments, EPS and ADS subsystems each. \\ \hline d & _Challenge:_ Structure design heritage & Shinen-2’s legacy structure with location for _Origin:_ Schedule for delivery on time control, fields of view of antennas and sensors. \\ \hline e & _Challenge:_ Attitude determination and control vs attitude determination & An attitude determination only approach was adopted to meet schedule and cost constraints. \\ \hline e & _Origin:_ Schedule for delivery on time and keeping the CPD and magnetometer readings with reduced influence & Use of avionics components from Shinen-2 and other small satellite missions wherever possible. \\ \hline f & _Challenge:_ COTS design heritage from previous missions & Magnetometer instrument location was designated in the top panel of the satellite to reduce complexity from boom deployable system while keeping the schedule and measurements quality. \\ \hline h & _Challenge:_ Launch date fixed by JAXA & Adopted a modular design approach, with re-use of the same microcontroller and other circuitry in all the subsystems. This also maximized software reuse. \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Design challenges and adopted solutions. In the case of the satellite's top panel, all the space available is dedicated to accommodate the material mission assembly, the magnetometer instrument and a GNSS receiver antenna. The magnetometer was placed on the top panel, as far as possible from other subsystems and particularly the switching voltage regulators in order to reduce the noise in the magnetic field measurements (explained further in section h). The DLP electrodes were located on opposite sides of one of the hexagonal panels close to the ECU, with their exact location and length tailored so as to comply with the allowed physical envelope  
Figure 8: Operation of the main payloads as described in Processes 3 and 4 in Section 2.5. (**a**) Communication sessions between the satellite and Kyutech ground station in Japan occur in two periods, during the day at around 13:00 and during night time at around 01:00. (**b**) Mission execution for CPD, DLP and ADS in a specified region that is pre-selected and configured via a command during the communication sessions with the satellite. of 50 cm \(\times\) 50 cm \(\times\) 50 cm dictated by the HII-A rocket.