“Communicating from Earth to any spacecraft is a complex challenge, largely due to the extreme distances involved. When data are transmitted and received across thousands and even millions of miles, the delay and potential for disruption or data loss is significant. Delay/Disruption Tolerant Networking (DTN) is NASA’s solution to reliable internetworking for space missions.
The moon is about 250 thousand miles away and Mars is 140 million miles away on average. To communicate across these vast distances, NASA manages three communication networks consisting of distributed ground stations and space relay satellites for data transmission and reception that support both NASA and non-NASA missions. These are the Deep Space Network (DSN), the Near Earth Network (NEN), and the Space Network (SN).
For previous missions from low-Earth orbit to deep space, NASA has used point-to-point (direct) or single relay links to communicate with spacecraft; this operates much like the phone system by directly connecting two communication nodes. While this approach has been successful for previous missions, future exploration concepts will introduce much more complex communication needs, with data transfer between many nodes. These transmissions will need to operate like the Internet here on Earth – involving multiple hops via relay ...