## 2 Materials and Methods--Implementation, Integration, and Testing of the IDEASSat Flight Model
### IDEASSat Satellite Subsystems  
As a spacecraft, IDEASSat was an integrated system composed of multiple subsystems, including the electrical power subsystem (EPS), telecommunication system (COMM), attitude determination and control subsystem (ADCS), command and data handling subsystem (CDH), spacecraft flight software (FSW), structure and mechanisms (STR), and thermal control subsystem (TCS). The entire spacecraft system was designed and integrated in-house, using a combination of commercial off the shelf (COTS) and self-developed subsystems.  
The solutions used to implement the spacecraft subsystems are shown in Table 1, as well as their technological readiness level (TRL) at the time of spacecraft decommissioning. Subsystems developed in-house are further denoted with an asterisk. During the preliminary design phase of the mission, it was decided to use self-developed subsystems for those where there was a reasonable level of confidence that the flight model requirements and specifications could be met within a two-year development period. These included the EPS, CDH, FSW, STR, and TCS, as well as the UHF tape measure antenna and the CIP payload. Commercial-off-the-shelf (COTS) solutions were utilized for subsystems where in-house development was not deemed feasible given the time available and requirements defined. In this case, there was a strong preference for COTS solutions with prior successful flight heritage (TRL 9), in order to minimize risk and maximize reliability. Additional details of the individual subsystems will be presented in the following subsections.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Subsystem** & **Solution** & **TRL** \\ \hline \multirow{3}{*}{ADCS} & Blue Canyon Technologies XACT-15 & \multirow{3}{*}{9} \\  & with NovAtel OEM-719 GPS Receiver & \\  & SpaceQuest TRX-U Transceiver & 9 \\  & UHF Tape Measure Antenna * & 9 \\  & CPUT STX-C Transmitter & 9 \\  & CPUT Cubesat S-Band TX Patch Antenna & 9 \\  & NCU EPS Controller Board * & 8 \\  & Li-Ion Battery Module * & 9 \\  & AzurSpace TJ Solar Cell Assembly 3G30A & 9 \\  & Solar Panel PCB * & 9 \\  & Microsemi Smartfusion2 & 9 \\  & System-On-Module & 9 \\  & NCU CDH Interface Board * & 9 \\  & IDEASSat Flight Software * & 9 \\  & STR & NCU 3U Bus * & 9 \\  & Thin Film Battery Heater * & 9 \\  & Passive Thermal Conduction Pathways * & 9 \\  & Payload & Compact Ionospheric Probe * & 8 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Subsystem solutions used to implement IDEASSat FM and TRL at time of decommissioning. Subsystems developed and fabricated in-house are designated by an asterisk (*).  
Figure 1 shows the location distribution of the spacecraft components implemented in the flight model. The figure does not include the wiring and harnessing. The lower right corner defines the body frame coordinates for the spacecraft.  
From the \(-\)Z to \(+\)Z direction, we use different colors to mark the different components inside the spacecraft, which are respectively the Compact Ionospheric Probe (CIP) payload, S-band transmitter module, CDH, EPS power control board, battery module, ADCS, UHF transceiver, UHF antenna deployment module. On the \(+\)Y side, there is an S-band patch antenna, a body-mounted solar panel on the \(-\)Y side, and a GPS receiving antenna and coarse sun sensor are also arranged near the \(+\)Z end of the \(+\)Y face.  
IDEASSat's main task was to perform in situ measurements of the ionosphere. Its orbit was set to a 500 km sun-synchronous orbit, which could pass over the same ground station 4 times a day. Of these four passes, two were at relatively low elevation angles where only limited communication was possible. The local time of descending node (LTDN) was constrained to being between 10:00 and 12:00. This was motivated by a desire to combine the IDEASSat observations with those of the FORMOSAT-5 Advanced Ionospheric Probe (AIP) at 720 km and 10:30 LTDN to resolve measurements at two altitudes with similar local time.