One of the big challenges for NASA missions in orbit or on other planets and in the space between is communications. Sending data to and from spacecraft or rovers on the surface of Mars can take a long time even at the speed of light.

NASA has announced that it is now testing a new type of deep space communications, and while we are still far from the sub-space communications we see on sci-fi shows, the new system is a significant improvement over existing communications methods.

NASA is comparing the new communications system to a type of deep space internet. NASA manager of space-networking architecture, technology, and standards Adrian Hooke said, "This is the first step in creating a totally new space communications capability, an interplanetary Internet."

Internet communications on earth is made possible by the TCP/IP protocol. The new network being tested by NASA is based on Disruption-Tolerant Networking (DTN). One NASA test has used DTN to transmit dozens of images to and from NASA spacecraft around 20 million miles from Earth.

The new software protocol is able to withstand delays, disruptions, and disconnections that can happen in space as a spacecraft moves behind a planet, during solar storms, and long communications delays. NASA uses communications from Mars as an example and says that sending or receiving data from Mars can take anywhere from three and a half minutes to 20 minutes even at the speed of light.

Whereas the TCP/IP protocol internet users are familiar with assumes a constant connection, DTN does not. When data is sent using DTN and the destination path can’t be found the data packets are kept by each network node until it can communicate safely with another node at a later point. The data is eventually sent to the end-user despite delays encountered.

The DTN protocol was designed in partnership between NASA and Vint Cerf, a vice president at search giant Google. Leigh Torgerson from the JPL told the AP, "In space today, an operations team must manually schedule each link and generate all the commands to specify which data to send, when to send it, and where to send it. With standardized DTN, this can all be done automatically." The automatic scheduling and command component of the DTN protocol should mean that the communications workload for ground controllers and astronauts in space would be reduced.

NASA ran a month long test in October using the NASA Epoxi spacecraft that is en route to encounter the Hartley 2 Comet two years from now. Epoxi was used as a Mars data-relay orbiter. The simulated interplanetary network had ten nodes including Epoxi. The other nine nodes were simulated on the ground at the JPL to represent Mars landers, orbiters, and ground control stations. NASA plans to begin testing of the network from the ISS next summer.

NASA says that a new communications network using the highly-fault tolerant DTN protocol could enable a variety of new missions form complex space flights with multiple spacecraft and ensure reliable communications for astronauts on the moon.