November 9, 2012
Experimental Interplanetary Internet Test From International Space Station
Lee Rannals for redOrbit.com - Your Universe Online
Space station Expedition 33 commander Sunita Williams used a NASA-developed laptop in October to remotely drive a small LEGO robot at the European Space Observatory Center in Darmstadt, Germany.
The experiment used NASA's Disruption Tolerant Network (DTN) to simulate a scenario in which an astronaut in a vehicle orbiting a planetary body controls a robotic rover on the planet's surface.
"The demonstration showed the feasibility of using a new communications infrastructure to send commands to a surface robot from an orbiting spacecraft and receive images and data back from the robot," said Badri Younes, deputy associate administrator for space communications and navigation at NASA Headquarters in Washington. "The experimental DTN we've tested from the space station may one day be used by humans on a spacecraft in orbit around Mars to operate robots on the surface, or from Earth using orbiting satellites as relay stations."
NASA's DTN architecture is a new communications technology that enables standardized communications similar to the Internet to function over long distances and through time delays associated with on-orbit or deep space spacecraft.
The DTN suite features a Bundle Protocol (BP), which is almost equivalent to the Internet Protocol (IP) that serves as the core of the Internet on Earth.
While IP assumes a continuous end-to-end data path exists between the user and a remote space system, DTN accounts for disconnections and errors.
In DTN, while waiting for the next link to become connected, bundles are temporarily stored and then forwarded to the next node when the link becomes available. This ability enables the network to be more tolerant of delays and disruptions likely to occur between planets, satellites, space stations and distant spacecraft.
"It's all about communicating over large distances, because the 'normal' internet doesn't expect that it may take minutes before something is sent for it to arrive," Kim Nergaard from ESA told BBC News.
NASA's work on its futuristic Internet is part of the agency's Space Communication and Navigation (SCaN) Program. This program coordinates multiple space communications networks and network support functions to regulate, maintain and grow NASA's space communications and navigation capabilities.
The space station serves as a platform for research focused on human health and exploration, technology testing for enabling future exploration, research in basic life and physical sciences, and Earth and space science.
The technology was first tested back in November 2008, when NASA successfully transmitted images to and from a spacecraft 20 million miles away with a communications system based on the Internet.
The system uses a network of nodes to cope with delay. If there is a disruption, the data gets stored at one of the nodes until the communication is available again.
"With the internet on Earth, if something is disconnected, the source has to retransmit everything, or you lose your data," Nergaard told BBC. "But the DTN has this disruption tolerance, and that's the difference - it has to be much more robust over the kind of distances and the kind of networks we're talking about."