## 2 Literature Review
### Systems Engineering
#### 2.2.2 Parametric Method  
In the parametric method, mathematical equations or algorithms are used based on spacecraft characteristics such as mission type, payload mass, and payload power to estimate the satellite mass [30]. After estimating the initial mass budget through the average mass budget table, as discussed in the previous section, the parametric method is used to obtain a detailed, mass budget for each and every subsystems based on detailed mission requirements. But for this research, the aim is to quantify midpoint indicators for a generic LEO constellation with limited available Federal Communications Commission (FCC) data, which means the parametric method cannot be used for all subsystems. Hence, the average mass budget table is used for most of the subsystems, and the parametric model is used for the propellant. The key reason is that data regarding orbit change, satellite total mass, and satellite lifetime are available. Therefore, a parametric model is employed to obtain a detailed estimate of propellant mass. Consequently, this paper utilizes a combination of the average mass budget method and the parametric method. Propellant mass data are predicted using a parametric method, supported by FCC filings submitted to the government. The FCC serves as a regulatory body overseeing communications in the United States, including telecommunications, broadcasting, and satellite services [28]. It regulates satellite operators within the country. Companies and individuals must submit \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Subsystem** & **No Prop** & **LEO with Prop** & **High Earth** & **Planetary** \\ \hline Payload & 41\% & 31\% & 32\% & 15\% \\ Structure and mechanisms & 20\% & 27\% & 24\% & 25\% \\ Thermal control & 2\% & 2\% & 4\% & 6\% \\ Power (including harness) & 19\% & 21\% & 17\% & 21\% \\ Tracking, telemetry, and control & 2\% & 2\% & 4\% & 7\% \\ On-board processing & 5\% & 5\% & 3\% & 4\% \\ Attitude determination and control & 8\% & 6\% & 6\% & 6\% \\ Propulsion & 0\% & 3\% & 7\% & 13\% \\ Other (balance+launch) & 3\% & 3\% & 3\% & 3\% \\ Total & 100\% & 100\% & 100\% & 100\% \\ Propellant & 0\% & 27\% & 72\% & 110\% \\ \hline \hline \end{tabular}
\end{table} 
Table 1: The average mass, represented as a percentage of the dry mass, categorized according to the type of spacecraft for various subsystems [25]. orbital data to the FCC for various activities, and these filings are essential for maintaining regulatory compliance and transparency. Hence, every satellite operator must submit several documents, including orbital data and an orbital debris mitigation (ODM) plan as part of the application process, ensuring compliance with the regulations set forth by the FCC. The Debris Assessment Software (DAS) v. 3.2.6, developed by the NASA Orbital Debris Program Office, is utilized to evaluate adherence to NASA's guidelines for minimizing orbital debris during the planning and design phases of space missions. While the DAS helps ensure compliance with NASA's requirements, the FCC's regulations mandate additional disclosure requirements that go beyond the DAS outputs. The ODM plan must incorporate these supplementary disclosures. Including the DAS compliance matrix along with the relevant inputs and outputs from the NASA DAS code can streamline the application review process [31]. The DAS input and output usually contains satellite mass and orbital data [32]. These data can be considered as primary data submitted by satellite operators via filings to the FCC. Mass and orbital data are essential for performing space-specific LCA for the method discussed in this paper. On the international level, satellite operators are governed by the International Telecommunication Union (ITU). The ITU oversees a collaborative framework for coordinating radio frequencies used by satellites on a global scale. This system aims to prevent interference both among satellite systems and between satellites and other radio communication networks [33].