# Internet of Spacecraft for Multi-Planetary Defense and Prosperity
## 5 Multi-Planetary Detection, Communications, and Defense: Live Long and Prosper
### Evolving the Networks of Survey Stations  
Based on the features and characteristics of asteroids/comets and related detection technologies, building and deploying more space-based survey stations with multiple techniques can accelerate the discovery of all potentially hazardous objects (PHOs). Furthermore, with minimal interference from Earth, space-based telescopes and spacecraft can more effectively survey the universe, with access to the full sky when deployed properly. In addition, the space-based survey stations are connected with on-ground stations and resources to form a more comprehensive and reliable network for PHOs detection. Next, we propose a framework for solar communication and defense networks (SCADN) which consists of the following critical components:  
1. A large number of survey stations (on spacecraft) will be deployed into various orbits across the entire solar system to form an enormous Internet of spacecraft (IoS) networks. As humans are supposed to become a multi-planetary species after extra-terrestrialization, the colonization of other celestial bodies could also fall victim to asteroid/comets impact. For example, due to the lack of a thick atmosphere as on Earth, Mars could be more vulnerable to the impact of near-Mars objects (NMO). Moreover, Jupiter and Saturn, the gas giants which are 318 times and 95 times as massive as Earth, can affect and steer some asteroids away from Earth, thus providing some protection to humanity. However, Jupiter and Saturn attract asteroids/comets to their regions and increase the impact probability on their moons including Europa [151], Titan [152], and Enceladus [15] which are particularly interesting and may be possible sites for human colonization. Similarly, some moons of ice giants Uranus and Neptune also can serve as humanity's colonization and outpost for even further expeditions in the universe. Consequently, deploying survey stations and spacecraft into regions/orbits of Mars, Jupiter, Saturn, Uranus, and Neptune is also crucial. 2. As illustrated in Figure 17, for each planet in the solar system, multiple survey stations/spacecraft are deployed in the planet's orbit. In the SCADN, the specific locations for accommodating these spacecraft can be on Lagrange points where the gravitational forces of the two large bodies and the centrifugal force balance each other so that spacecraft only require minimal orbital corrections. Take Earth for example; multiple survey stations/spacecraft can be deployed on Earth-Sun Lagrange points, L2, S-E, L3, S-E, L4, S-E, and L5, S-E, respectively. There are several features enabled by adopting such a strategy. First, L2, S-E, which has a distance of around 0.01 AU from Earth, can enable a high-performance survey (with minimal interference from the Sun) to the space in the direction away from the Sun but a reliable communication with Earth. Second, L3, S-E, L4, S-E, and L5, S-E can help survey space more thoroughly and completely than on/near-Earth stations. For instance, the object within a specific elongation from the Sun, which is a region of the sky giving no access to ground-based telescopes, will be discovered by stations deployed in these locations. Therefore, the probability of failed detection and the absence of alarms of incoming objects from outer space (such as the Chelyabinsk meteorite) will be minimized. 3. Furthermore, as shown in the exemplary illustration, the Lagrange points of other planets such as Venus, Mars, Jupiter, and Saturn, will also be deployed with survey stations/spacecraft. For example, Venus has an average distance of 0.72 AU from the Sun and orbits the Sun faster than other outer planets. Therefore, deploying survey stations/spacecraft into the four Lagrange points of Venus can also help survey the potentially hazardous objects approaching other outer planets (of Venus) more effectively.