NASA has successfully tested the first deep space communications network modeled on the Internet, the U.S. space agency reported Tuesday.

NASA engineers used Disruption-Tolerant Networking software, or DTN, to transmit dozens of images to and from a NASA science spacecraft located about 20 million miles (32 million km) from Earth.

"This is the first step in creating a totally new space communications capability, an interplanetary Internet," said Adrian Hooke, team leader and manager of space-networking architecture, technology and standards at NASA headquarters in Washington.

NASA and Vint Cerf, a vice president at Google Inc., partnered 10 years ago to develop the software protocol. The DTN sends information using a method that differs from the Internet's Transmission-Control Protocol/Internet Protocol, or TCP/IP, communications suite, which Cerf co-designed.

The Interplanetary Internet must be robust to withstand delays, disruptions and disconnections in space. Glitches can occur when a spacecraft moves behind a planet, or when solar storms and long communications delays happen.

Unlike TCP/IP on Earth, DTN does not assume a continuous end-to-end connection. In its design, if a destination path cannot be found, the data packets are not discarded. Instead, each network node keeps the information as long as necessary until it can communicate safely with another node. This store-and-forward method means information does not get lost when no immediate path to the destination exists. Eventually, the information is delivered to the end user.

"In space today, an operations team must manually schedule each link and generate all the commands to specify which data to send, when to send it, and where to send it," said Leigh Torgerson, manager of NASA's DTN Experiment Operations Center. "With standardized DTN, this can all be done automatically."

NASA began a month-long series of DTN demonstrations in October. Data was transmitted using NASA's Deep Space Network in demonstrations occurring twice a week. Engineers used NASA's Epoxi spacecraft as a Mars data-relay orbiter. Epoxi is on a mission to encounter Comet Hartley 2 in two years. There are 10 nodes on this early interplanetary network. One is the Epoxi spacecraft itself and the other nine, which are on the ground, simulate Mars landers, orbiters and ground mission-operations centers.

This is the first in a series of planned demonstrations to qualify the technology for use on a variety of upcoming space missions. A NASA-wide demonstration using new DTN software loaded aboard the International Space Station is scheduled to begin next summer in the next round of testing. NASA expects that in the next few years, the Interplanetary Internet could enable many new types of space missions.

(Xinhua News Agency November 19, 2008)