NASA successfully tested an internet-like protocol for space, which could some day automate communication with craft and bases beyond Earth’s orbit (Illustration: NASA/JPL)

NASA has finished its first deep-space test of what could become an ‘interplanetary internet’. The new networking commands could one day be used to automatically relay information between Earth, spacecraft, and astronauts, without the need for humans to schedule transmissions at each point.

Spacecraft beyond Earth’s orbit usually communicate directly with Earth – the first to do so through an intermediary were the Mars Explorations Rovers, which launched in 2003. The Spirit and Opportunity rovers transmit data to orbiters, which then send the data back to Earth.

But human intervention is still required to schedule communications sessions for orbiters and landers. “The traditional method of operations is largely manual,” says Jay Wyatt of NASA’s Jet Propulsion Laboratory in Pasadena, California. “People get in a room and decide when they can send data.”

A new method would automate and streamline this process by sending data through an interplanetary ‘internet’. Just as data is sent from one point to another on the internet via a linked network of hubs, or nodes, spacecraft scattered throughout the solar system could be used as nodes to transmit data through space.


Last week, NASA completed a month-long test of a simulated network of Mars landers, orbiters and mission operations centres on Earth.

For the test, dozens of images of Mars and its moon Phobos were transmitted back and forth between computers on Earth and NASA’s Deep Impact spacecraft. The craft, which sent an impactor into Comet Tempel 1 in 2005, has been renamed “Epoxi” now that it its mission has been extended to search for extrasolar planets.

Internet pioneer

Also transmitted were a four-node diagram of the internet’s ancestor, ARPANET, and a photograph of networking visionary J C R Licklider.

The test was the culmination of a collaboration between internet pioneer Vinton Cerf and NASA that began in 1999.

The new protocol is somewhat different from the one that forms the backbone of the internet, called TCP/IP. On Earth, if some data is lost between a sender and a recipient, the two communicate back and forth until all the information is sent.

That ‘handshake’ works well on Earth, where the network is almost always continuously connected, says Adrian Hooke, team leader at NASA Headquarters in Washington, DC.

But in space, probes pass behind planets and out of range, power outages are common, and distances between planets vary as the planets move in their orbits. In addition, at distances not far beyond the Moon, the time required to beam data between a sender and a recipient makes back-and-forth communication between the two inefficient, says Hooke.

Space hackers

To avoid such issues, the new protocol, called Disruption- or Delay-Tolerant Networking (DTN), commands each node in the network to store information until it can find another node that can receive the information.

Data is relayed in a chain and should only need to be transmitted once. “The nodes themselves can take care of making sure the data moves progressively from the source to its destination,” Hooke told New Scientist.

To guard against hackers, the data transmitted over DTN is encrypted. In order to transmit or accept data, a node must identify itself to its companion, a concept called ‘mutual suspicion.’

International network

On Earth, DTN has been tested in a variety of projects – from boosting cellular connections in remote locations and improving battlefield communications to using snowmobiles to extend internet access to reindeer herders.

Hooke hopes to incorporate the protocol on upcoming space missions, beginning with robotic missions to the Moon. “The goal is by the end of 2011 to have these protocols ready to go out of the box, so we can give them to project managers to load onto spacecraft,” Hooke says.

The team is also working to get the protocol accepted by the international community, so that other spacecraft could join the network.

Spacecraft communicating through DTN could also alleviate traffic on NASA’s Deep Space Network, a collection of ground-based radio antennas used to communicate with space probes. Some say the network will soon have trouble meeting demands on its time.

The DTN protocol has been erased from Epoxi, one of the conditions for use of the spacecraft, Hooke says. But the team plans to set up a permanent DTN node at the International Space Station. The protocol will be uploaded to a payload aboard the station in mid-2009.