Networking in-between planets is subjected to various disruptions and delays. As a planet rotates, ground stations will lose communications with spacecrafts or satellites on other planets (such as Mars). Even the Sun itself can block planets as they rotate on different sides on the Sun. Delay/Disruption Tolerant Networking (DTN) is a network that has frequent Disruptions or long Delays in the connection between the network devices. Using a Store and Forward technique, application data is bundled together and stored locally at each node and then forwarded to the next node when access is available...
This is useful for Interplanetary Networking. Therefore communications satellites are useful to relay the data...
Networking in-between planets is the future of the Internet.