## 8 System Design
### Volume Budget  
A volume budget for OpenOrbiter has been created based upon the space utilization assignment depicted in Figure 1. The OPEN framework spacecraft design includes four locations for placing boards, four locations for battery placement and a central payload area. These board slots have been utilized for a payload processing board, a flight computer board, a power and attitude determination and control board, and a telemetry, tracking and control board.  
\begin{table}
\begin{tabular}{|p{142.3 pt}|p{142.3 pt}|} \hline
**Requirement** & **Fulfilling Architecture Element** \\ \hline
1. A functional spacecraft shall be designed, developed, deployed and demonstrated. & Attained by: Spacecraft Bus \\ \hline
2. The spacecraft shall be compliant with revision 12 of the CubeSat form factor and launch provider integration standards (with the later taking precedence over the former in case of any conflict). & Attained by: Spacecraft Bus \\ \hline
3. The spacecraft shall be capable of producing imagery with a minimum spatial resolution of 150 meters & Attained by: Payload, Orbit and Subject \\ \hline
4. Software shall be developed which can produce a 3x increase in spatial resolution over the optical resolution. & Attained by: Spacecraft Bus \\ \hline
5. The spacecraft shall be capable of executing critical elements of constellation operations including position determination and attitude correction & Attained by: Spacecraft Bus \\ \hline
6. The mission shall incorporate students in the design, development and operation of the spacecraft. & Attained by mission implementation approach, see Section 3.2.1 \\ \hline
7. The spacecraft shall have sufficient pointing knowledge to determine whether a desired target has been imaged. & Attained by: Spacecraft Bus and Orbit, Subject \\ \hline
8. Relevant documentation to allow future fabrication of all in-house designed hardware elements shall be produced. & Attained by mission implementation approach, see Section 3.2.2 \\ \hline \end{tabular}
\end{table}
Table 4: Implementation of Requirements by Mission Architecture.  
The volume budget, presented in Table 5, is based on the presumption that the full space of each allocated area will be utilized for the applicable system. While this is, of course, an oversimplification, it is appropriate, as the space is not available for use by any other system. Additionally, the design makes full use of the overhang area (thus a usable cross-section space of 11.2 cm \(\times\) 11.2 cm). The percentages presented in Table 6 are based on the subsystem's percentage of the typically utilized CubeSat form factor of 10 cm \(\times\) 10 cm \(\times\) 10 cm, to facilitate comparison to other missions.  
Figure 1: OpenOrbiter Configuration.  
\begin{table}
\begin{tabular}{|c|r r|} \hline
**Subsystem** & \multicolumn{2}{|c|}{**Volume Allocated**} \\ \hline Payload & & \\ \hline Payload Area & 250 & cm\({}^{3}\) \\ \hline Payload Board & 154.5 & cm\({}^{3}\) \\ \hline Onboard & & \\ Processing & 154.5 & cm\({}^{3}\) \\ \hline ADCS & 77.3 & cm\({}^{3}\) \\ \hline Power & & \\ \hline Board & 77.3 & cm\({}^{3}\) \\ \hline Batteries & 57.2 & cm\({}^{3}\) \\ \hline TT\&C & 154.5 & cm\({}^{3}\) \\ \hline \end{tabular}
\end{table}
Table 5: Volume Budget.  
Table 6, in addition to presenting the volume as a percentage of the spacecraft's volume, also compares this to values presented in _Space Mission Engineering: The New SMAD_ (commonly referred to as SMAD 4). As no values for volume are presented in SMAD 4, the mass values were used, based on incorporating the simplifying assumption of a consistent density between subsystems. This is, of course, not completely accurate; however, due to the need to generally keep the center of mass and center of volume in close alignment (to facilitate maneuver calculations) it is useful for comparison purposes.