November 09, 2012, 8:26 PM — Late last month in Germany, a robot made its first moves on Earth under commands from an orbiting spacecraft.
Though that may sound ominous, it doesn't represent an impending threat to humankind. The robot was made of Legos, and it only traversed a European Space Agency test facility. The commands were sent by Sunita Williams, commander of the 33rd expedition of the International Space Station. The ESA-led experiment may have helped lay the groundwork for future expeditions to the Moon, Mars and beyond.
ESA and NASA carried out the exercise to test Disruption Tolerant Networking, a set of protocols designed for communication across the void of space. Researchers created DTN to overcome problems that prevent space missions from using Internet Protocol, the system that runs the Internet and most other networks on Earth. In the process, they may create a technology that helps soldiers keep in touch across war zones and consumers use smartphones as they move in and out of cell coverage.
The Internet doesn't work in space because it takes too long to send data packets across the enormous distances. Even at the speed of light, a one-way transmission from Earth to the Moon has a built-in delay of 1.7 seconds, and one from Earth to Mars would face an eight-minute delay. Space networks also suffer from higher error rates than the terrestrial Internet does because of interference from solar radiation, and their transmissions can be blocked temporarily as celestial bodies move through space.
"As NASA extends its reach to the Moon and beyond, a networked architecture such as DTN will be required to successfully complete these missions," the agency wrote on its Web page about the project. NASA envisions DTN being used between assets on the surface of planets and sister spacecraft orbiting above, or between craft in deep space and command centers on Earth.
While IP expects a continuous, end-to-end data path between two devices using it, DTN sends data on its journey one "hop" at a time. At its heart is the Bundle Protocol, which stores bundles of data at each hop until the next link becomes available and then forwards them.
Spacecraft and all forms of surface vehicles have been communicating by radio ever since the dawn of the Space Age, but the technologies they use are specialized and custom-built. NASA and ESA hope to make DTN into the equivalent of IP for space, a standards-based, publicly available protocol. That would reduce labor costs for setting up communications for each mission, NASA said.
Having a standardized communication protocol will become more important if space exploration escalates to setting up bases on the Moon or other planets, said Adrian Hooke, NASA's space DTN project development manager.