Scientists Plan Interplanetary Internet Protocol

The Internet's TCP/IP protocol could be headed for outer space.

For the last several years, Vint Cerf, co-creator of TCP/IP and now a VP at Google (Nasdaq: GOOG), has worked with colleagues from NASA and elsewhere to extend Internet connectivity to deep space.

If their work succeeds, astronauts on manned missions to Mars and other distant locations could keep in touch with researchers worldwide (while maintaining their Twitter links). (Notably, Cerf's work began prior to his start at Google and continues independently of that company.)

Deep space presents daunting challenges to Internet communications. These include distance; line-of-sight obstructions (like meteors); weight issues (high-powered antennas are often too heavy to send on a space mission); and the need for specialized "hardened" equipment that can automatically heal itself or be fixed via remote (very remote) network management.

Cerf and others are engaged in several efforts to address these challenges. One approach is to modify the satellite payload design now used to link IP routers with Ka-band satellites in government and business networks. Some researchers think an adjusted satellite-based IP would work fine, as long as links were made to planets or highly concentrated communities in space, mimicking the successful one-to-many transmission patterns of today's high-powered Ka-band gear.

"One could envision using IP to connect a fleet of rovers operating in close proximity on Mars, or among members of a spacecraft constellation in deep space, or orbiting Earth or another planet," says Keith Scott, principal engineer at The Mitre Corp.

In the future, Scott envisions routers afloat in deep space: "Some spacecraft might operate as a router as we think of Internet routers, autonomously responsible for forwarding data received from some external source."

NASA is investigating the potential for a group of six circling satellites to establish communications for Mars one day. According to Scott, the NASA Constellation program will advance the use of IP in continuously connected near-Earth environments.

Researchers from NASA and Mitre also have been working with Vint Cerf on delay-tolerant networking (DTN) to solve the shortcomings of pure IP in space.

"There are sometimes long periods of disconnection in such networks, so DTN uses a store-and-forward model where DTN messages may be stored at intermediate nodes while waiting for a communication link to become available," says Scott. "Reliability in DTN is provided by a mechanism called custody transfer, where nodes in the network can assume responsibility for retransmitting lost messages. This allows for retransmissions from inside the network rather than having to retransmit data from the source, as is the case with TCP."

NASA has initiated a new program designed to bring DTN to a state of flight readiness by 2010. "This will involve a number of flight demonstrations on deep-space spacecraft and the international space station to test the protocol's performance and capabilities," Scott notes. "The 2010 goal is designed to bring DTN to a sufficient level of maturity to incorporate it into designs for robotic and human lunar exploration. This effort also supports the international standardization of DTN as the space internetworking layer supported by the major space agencies."

As deep space Internet initiatives intensify, both commercial and social opportunities will open up -- virtual interplanetary space tours, for instance. "There will be more demonstrations of IP in space over the next five years," says Rick Skinner, VP of Strategic Planning in Global Communications Systems for Lockheed Martin Space Systems Co. "This will further work to define the business case for commercial Internet in space systems."

Mitre's Scott agrees, but he adds that there is also a cultural issue with space networking that could keep it out of the range of public use, for awhile at least. "The culture of space missions is understandably conservative, leading to the desire to manage all aspects of spacecraft operation... Some operations will be out of the direct control of ground operators. Conversely, it takes a large degree of trust to design a spacecraft, such as the Phoenix lander, that is dependent on relay satellites to operate."

— Mary E. Shacklett, President of Transworld Data