Network World is a weekly IT publication that provides news and information to network executives.This Network World article (http://www.networkworld.com/community/node/25502) describes plans for modular satellite technology, which is intended to replace present day all-in-one, monolithic spacecrafts. The project sponsored by Defense Advanced Research Projects Agency (DARPA) hopes to solve issues of scalability and reliability by splitting the standard satellite systems and allowing the different “fractionated modules” to change function if necessary by replicating functions of each other. Modules can be physically connected once in orbit or can be linked together via a wireless network to create a virtual satellite.

The advantages of the proposed multi-module system can be described using the concepts we have studied in class. Essentially, we are taking a single node network, or on a micro scale, a system in which a failure of a single component implies a failure of the entire network, and we are changing it into a network, consisting of individual modules (nodes). Since all nodes are interconnected, failure of one node does not cause the entire network to fail. Segmentation of a network makes it more robust. 

Multiple networks might have identical or similar components, which can be shared in case of emergency. For example, in an undirected graph shown above, two networks, Network 1 and Network 2, node A and node B are either identical or serving the same purposes in their respective networks. If node A fails, B can temporarily replace node A by embedding itself into Network 1. Multiple components (subnetworks) may choose to use the same module, for instance to save money, however in this case this module spans a structural hole, and its failure will damage both networks at once, so this kind of sharing should be used only in emergency situations.

Modular network of satellites displays a lot of flexibility, since any new launched element can quickly fit into an already existing structure by forming new edges with already existing fully-connected component (as seen in the example above). Multiple new nodes that have strong links to an existing component will be more likely to establish new edges between each other, which can be linked to the Strong Triadic Closure Principle. Naturally, we expect modules linked to the same modules to have links between each other. This is just like homophily and proximity in social networks.

Other advantages of modular satellites include upgradeability and incremental deployment of capability to orbit, which is related to how easy it is to add another node to an already existing network, and reduced integration and testing due to subsystem decoupling, which is related to ability of each node to exist independently of the network.

According to Network World, the first companies and their partners awarded contracts for this project this week included Orbital Sciences ($13,648,758); Northrop Grumman Space and Mission Systems ($6,159,866); Boeing ($12,891,049); and Lockheed Martin Space Systems ($5,762,781). It will be exciting to see these new virtual satellites being developed and launched in the near future. (…or even better: to work on designing and developing them).