Scientists are discovering new things about our universe all the time--including the existence of Earth-like sister planets. But sending vehicles--even unmanned ones--to explore the distant reaches of the galaxy presents myriad challenges, including the lack of a reliable system of communicating with vehicles over (literally) astronomical distances. Solar storms, interference from planets, and other issues throw snags in the type of communication networks we use to send and receive information here on Earth. What’s a robot with deep-space wanderlust to do?
This month, NASA and the European Space Agency completed the first test of an Internet designed for outer space: Disruption Tolerant Networking, or DTN. Led by Vint Cerf, a vice president at Google, the team has spent the past decade developing an interplanetary Internet, impervious to the many challenges involved in transmitting information over many millions of miles. Internet historians will know Cerf as one of the original authors of this planet’s Internet. “The methods we use in the terrestrial Internet don’t quite work when we’re going at interplanetary distances,” Cerf explains in a NASA-produced video. “After quite a bit of work, we realized we needed to design a new set of communication protocols.”
Last month, NASA astronaut Sunita Williams tested those new protocols for the first time. From her perch on the ISS where she is commander, Williams controlled a small Lego robot in Darmstadt, Germany. "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,” explains NASA’s Badri Younes, “or from Earth using orbiting satellites as relay stations."
How does DTN differ from the Internet that enabled your computer to load this page? In simple terms, Cerf’s so-called Bundle Protocol tells machines to save incomplete data they’ve received, even if the transmission is disrupted by interference. DTN instructs recipient machines to save the bundles until they’re completely transmitted, no matter how long that takes. Then, the data packets are forwarded to the next recipient, in a system NASA calls "store-and-forward." “[It’s] similar to a basketball player passing the ball down the court to other players nearer to the basket, who hold it as the team assembles to await the final pass to a player who has a clear shot at the goal,” explains Adrian Hooke, manager of NASA’s Space DTN project at NASA headquarters.
Though it may be a while before you’re sending YouTube videos to your evil twin on a far-off alternate Earth, these early tests have huge implications for NASA and the ESA. For now, the team will continue the testing and research phase, challenging the system by using it to control several Earth-bound robots from the ISS.