## 3 Mission Analysis
### Orbital Parameters LEO Design and Selection
The orbital elements of the LEO circular orbit chosen for this study are listed in Table 4.  
According to [41], for covering a specific area of low-latitude ground, a higher number of nanosatellites in a circular LEO orbit provides better coverage with good performances. Figure 7 shows the plot of the revisit time as a function of the number of satellites in the constellation. Using the findings from Figure 7, it is common practice to use between 8 and 12 satellites to produce a revisit time for a nanosatellite constellation of between 15 and \begin{table}
\begin{tabular}{c c} \hline \hline
**Orbit Type** & **CO** \\ \hline
**Semi-major axis** & A = 6771 km \\ \hline
**Inclination** & I = 49\({}^{\circ}\) \\ \hline
**Eccentricity** & E = 0.0017 \\ \hline
**RAAN** & 0\({}^{\circ}\) \\ \hline
**Argument of periapsis** & 0\({}^{\circ}\) \\ \hline
**True anomaly** & 0\({}^{\circ}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Chosen initial orbital elements. Figure 7: Revisit time versus the number of satellites. 20 min. There are several possible designs for nanosatellite constellations that are intended to cover the earth and maritime zones; however, they differ in terms of revisit time and response time for 100% of coverage. Figure 8 illustrates the performance outcomes (revisit time, response time, and access time) for various constellation configurations for South China Sea regions. The constellation distribution characteristics are depicted in this figure as C (number of nanosatellites in each orbit and number of orbit plans). Figure 8 illustrates that, for all constellation's configurations with various numbers of nanosatellites, the average access time for constellations in the South China Sea is around 8 min. According to the threshold performance requirements provided in Table 3, these data are acceptable and are probably the best technique to estimate transmission duty cycles; however, no final judgment has been taken on that matter to date. Defining access periods further and selecting a duty cycle and transmission time that maximizes the opportunity to obtain data are possible future tasks. The data shown in this figure indicate that the constellation of 12 nanosatellites distributed over 12 orbital plans performs exceptionally well in terms of revisit time and response time (according to Table 3). For this constellation, the maximum revisit duration and response time is 44.1 min. Nevertheless, the performances attained with a constellation based on eight orbital plans are still appropriate with only eight nanosatellites. For any clear-cut viewpoint, a compromise between several nanosatellites' costs and performances--specifically, their tolerable revisit and response times--is the best option. A constellation of 12 nanosatellites placed in the 12 orbital planes can be the most appropriate solution to be used to achieve 100% coverage, as shown in Figure 9, while considering the threshold performance requirements listed in Table 3. For this constellation, the maximum revisit duration and response time is 55.7 min. It might be possible to also revisit time according to the threshold performance requirements shown in Table 3 by forming a constellation of eight nanosatellites in eight orbital planes. To arrive at the appropriate mission analysis decision, as a compromise method, depending on the required and shorter revisit time (on the order of at least less than one hour), combinations of a reduced number of nanosatellites with constellation configuration were considered. Figure 9 displays the findings of each constellation's performances for the forest on the Chinese mainland, similar to Figure 8, where C (number of nanosatellites in each orbit and number of orbit plans) represents the constellation distribution parameters. Figure 8: Performance results of each constellation for areas in the South China Sea.