NASA has successfully tested the deep space Internet. "This is the first step in creating a totally new space communications capability, an interplanetary Internet," said NASA’s Adrian Hooke. During the test, NASA transmitted dozens of images about 20 million miles to the spacecraft Epoxi, on a two-year mission to the Comet Hartley. The communications system is currently comprised of ten nodes, nine of which are in at NASA's Jet Propulsion Laboratory in Pasadena, California, which simulated Mars landers, orbiters, and operations centers during the test.
“In the next few years, the Interplanetary Internet could enable many new types of space missions. Complex missions involving multiple landed, mobile and orbiting spacecraft will be far easier to support through the use of the Interplanetary Internet. It also could ensure reliable communications for astronauts on the surface of the moon,” says NASA.
While we earthers use the TCP/IP protocol here on the home planet, it is not suitable for interplanetary communications. Instead, NASA uses Disruption-Tolerant Networking (DTN), which works over long distances and is resistant to disruptions such as planets and solar storms. The delay in transmitting to Mars can take from 3.5 to up to 20 minutes at the speed of light.
“DTN is designed to accommodate a store-and-forward system, with built-in smarts. If one link in a communication chain is broken, a robot on Mars could decide for itself the next-best way to get its data back to Earth,” explains Alan Boyle, who writes for msnbc’s Cosmic Log.
The protocol was designed by NASA and Google’s Vint Cerf, one of the fathers of the Internet; it has been in development since 1999. DTN is also being used by the military for battlefield communication and for submarines, in Sweden to track reindeer movements, and to build communication grids in developing countries.
The international space station will begin testing the DTN connection next year.