## 4 Results
\begin{tabular}{c} **Revisit Time** \\ **(Minutes)** \\ **100 km** \\ \end{tabular}  } & \multirow{2}{*}{\ \begin{tabular}{c} **Revisit Time** \\ **(Minutes)** \\ **500 km** \\ **Altitude** \\ \end{tabular}  } & \multirow{2}{*}{ \begin{tabular}{c} **Revisit Time** \\ **(Minutes)** \\ **900 km** \\ **Altitude** \\ \end{tabular}  } \\ \hline
1 & 1 & 1 & 0 & 678.5 & 361.0 & 313.8 & 301.1 \\ \hline
1 & 1 & 1 & 30 & 566.4 & 301.8 & 259.2 & 244.1 \\ \hline
1  
The bar plots in Figure 7 delineate the revisit time for IoT nodes stationed at varied latitudes on Mars, representing the interval required for satellites in the constellation to re-establish communication with given IoT nodes on the Martian surface. The analysis shows that the revisit time varies across satellite configurations, with higher altitudes typically manifesting reduced gaps due to the extensive coverage footprint. This is particularly noticeable for the 100 km altitude satellites, which exhibit the most extended gaps across all latitudes. Moreover, the plots reveal that the revisit time is not only a function of altitude but is also significantly influenced by orbital inclination. Notably, the minimum revisit time is often associated with lower inclination angles. Figure 6: Contact duration for all analyzed Mars orbits and IoT devices at 0, 30, 60, and 90 degrees of latitude on Mars’s surface. According to these findings, it is recommended to use inclination angles close to 90 degrees to ensure complete coverage due to their scientific significance. As for the satellites' altitude, a higher altitude reduces the time it takes to revisit a location but also increases the communication distance between the IoT node and the satellite. On the other hand, a lower altitude reduces the contact duration and is more affected by the Doppler effect. An intermediate altitude of 500 km may be the most appropriate for both cases. To increase the frequency of revisiting a specific location on Mars, the number of satellites in orbit can be increased. Table 3 provides details of the revisit times for various satellite constellation configurations around Mars, with an inclination of 90 degrees. These configurations differ based on the number of satellites, their orbital altitude, and the latitude  
Figure 7: Revisit time for all analyzer Mars orbits and IoT devices at 0, 30, 60, and 90 degrees of latitude on Mars’s surface. of the IoT node, as per the Walker Star model proposal. As the number of satellites in a constellation increases, the frequency at which the satellites revisit a specific location decreases significantly. Among the evaluated configurations, a constellation with six or more satellites orbiting at an altitude of 500 km or greater would provide visit times of less than an hour and 20.5 min at the equator and even less for polar areas. This configuration would be optimal for receiving data from IoT nodes on the surface. Constellations with six or more satellites and 500 km high orbits reduce revisit times considerably compared to configurations with fewer satellites. The transmission distance simulation is performed using the Friis Model Transmission Equation in MATLAB. The simulation tests distances up to 2000 km between the IoT node and orbiting satellites, measuring the power received at the satellite. If the received power exceeds the receiver's sensitivity, the satellite can receive the transmission from the IoT node. Table 4 shows the parameters used in the simulation. The reception sensitivity of satellites is usually between \(-120\) and \(-140\) dBm. In our study, we opted for a sensitivity of \(-137\) dBm, which was also used in reference [51]. For the IoT node on Mars, the transmission power is set to 14 dBm, with a transmitting antenna gain of 2.15 dBi and a receiving antenna gain of 22.6 dBi. We evaluated the LoRa bands at 433 MHz and 868 MHz using a single channel, part of the LoRa standard for terrestrial and satellite communications [52].