## 3 Feasibility Analysis of IoT Architecture Utilizing LoRa Communications on Mars
### Analysis of the Interplanetary Communications for the Proposed Architecture  
Establishing good communication between Mars and Earth is vital for the proposed architecture's success. Therefore, proposing an analysis of interplanetary communications to address in detail the characteristics of Earth-Mars communications, such as distance, signal propagation time, and contact frequency (number of contacts in a time interval), is essential to guaranteeing the system's efficiency and reliability.  
This assessment examines the characteristics of the communication links between Earth, represented by NASA's Deep Space Network (DSN) [31], and a series of hypothetical Mars's orbiters. The DSN consists of three ground stations in Goldstone, California, USA; Madrid, Spain; and Canberra, Australia. These stations are strategically positioned around the globe to allow for continuous communication with spacecraft as Earth rotates (see Table 1 and Figure 5).  
To conduct this study, sixteen distinct orbits for the Mars segment have been defined, each characterized by a specific semi-major axis and inclination. The altitudes of these orbits above the Martian surface are set at 100, 500, 900, and 1300 km with inclinations at 0, 30, 60, and 90 degrees. These orbits have been selected to provide a comprehensive overview of potential operational environments for spacecraft around Mars, especially for the ISL with the satellite constellation (see Table 2).  
The lower-altitude orbits (100 km) represent low Mars orbit (LMO) missions, enabling high-resolution observation or efficient Martian surface and atmosphere data collection. These are particularly useful for scientific research, such as studying Martian geology or searching for water sources. The medium-altitude orbits (500 and 900 km) can be representative of communication and weather satellites, providing broader coverage and serving as relays for missions on the Martian surface. The high-altitude orbit (1300 km) would represent areostationary or areosynchronous orbits (terms analogous to \"geostationary\" and \"geosynchronous\" orbits used for Earth satellites but applied to Mars), which could be advantageous for constant communication coverage over specific areas of the Martian surface and the ISL with the satellite constellation.  
The range of inclinations from equatorial (0 degrees) to polar (90 degrees) ensures that the study encompasses different mission profiles. The given scenario's duration is set from 1 January 2025, for twice the synodic period (780 days \(\times\) 2), totaling approximately 1560 days or about 4.2 years. The synodic period of Earth and Mars is the time required for Earth and Mars to return to the same positions relative to each other and the Sun, allowing for the reoccurrence of similar geometric relationships between the two planets. This period is approximately 780 days or about 2.1 years. This duration is particularly representative for assessing the Earth-Mars communication link because it covers two complete synodic cycles.  
\begin{table}
\begin{tabular}{l l l l} \hline
**Location** & **Latitude** & **Longitude** & **Altitude (km)** \\ \hline Goldstone, CA, USA & 35.4266\({}^{\circ}\) N & 116.8899\({}^{\circ}\) W & 1.0 \\ \hline Madrid, Spain & 40.4316\({}^{\circ}\) N & 4.2491\({}^{\circ}\) W & 0.8 \\ \hline Canberra, Australia & 35.4020\({}^{\circ}\) S & 148.9819\({}^{\circ}\) E & 0.7 \\ \hline \end{tabular}
\end{table}
Table 1: NASA’s DSN ground stations.  
Figure 5: DSN and Mars orbit scenarios. (**a**) NASA’s Deep Space Network (DSN). (**b**) Mars orbital scenario and parameters.  
Each DSN station's unique geographical location and altitude offers a different look angle and communication window with each orbiter, making this analysis robust and significant for future Mars IoT mission planning and support. By evaluating these links, we can understand the challenges and capabilities of Earth-to-Mars communication, which is critical for efficient data backhauling between the IoT access network and the core or network server on Earth.