[/caption]In an initiative energized by Google Vice-President and Chief Internet Evangelist Vint Cerf, the International Space Station could be testing a brand new way of communicating with Earth. In 2009, it is hoped that the ISS will play host to an Interplanetary Internet prototype that could standardize communications between Earth and space, possibly replacing point-to-point single use radio systems customized for each individual space mission since the beginning of the Space Age.

This partnership opens up some exciting new possibilities for the future of communicating across vast distances of the Solar System. Manned and robotic space craft will be interconnected via a robust interplanetary network without the problems associated with incompatible communication systems…



“The project started 10 years ago as an attempt to figure out what kind of technical networking standards would be useful to support interplanetary communication,” Cerf said in a recent interview. “Bear in mind, we have been flying robotic equipment to the inner and outer planets, asteroids, comets, and such since the 1960’s. We have been able to communicate with those robotic devices and with manned missions using point-to-point radio communications. In fact, for many of these missions, we used a dedicated communications system called the Deep Space Network (DSN), built by JPL in 1964.”

Indeed, the DSN has been the backbone of interplanetary communications for decades, but an upgrade is now required as we have a growing armada of robotic missions exploring everything from the surface of Mars to the outermost regions of the Solar System. Wouldn’t it be nice if a communication network could be standardized before manned missions begin moving beyond terrestrial orbit?

“When we launch a spacecraft with a unique set of sensors onboard, we often end up writing special communication and application software that is adapted to that spacecraft’s sensor systems and manipulators,” Cerf said in response to the challenges space missions face each time they are designed.

The Internet uses standard TCP/IP protocols so billions of online entities are always compatible. Although there are limitations to the Internet, it has proven to be a highly flexible and scalable system, so with the help of Google, NASA hopes to push the Internet beyond Earth. “The Interplanetary Internet project is primarily about developing a set of communication standards and technical specifications to support rich networking in space environments,” Cerf added.

This all sounds very interesting, but the challenges with building such a system require some novel techniques. How do you deal with the limitation of the speed of light? After all, it can take light 40 minutes to travel to-and-from Mars, and up to 12 hours to Pluto and back. How do you cater for planetary rotation? The transmitters/receivers won’t always be on the correct side of the planet. What happens if a satellite signal is blocked by a planet, the Sun or a moon?

Vint Cerf says the disruption of data transmission has to be confronted with a delay- and disruption-tolerant networking system, otherwise known as DTN. “It will allow us to maintain communications more effectively, getting much more data because we don’t have to be in direct line of sight with the ultimate recipient in order to transfer data,” he said.

DTN will be based on store-and-forward methods used by TCP/IP systems; if there is a disruption in signal, the transmitting station will hold data packets until the signal is re-established. However, DTN will be more robust, catering for long transmission lag-times (such as the many-hour light transmission times between Earth and the outer Solar System). “We have to cope with the fact that there is a really high potential for delay and disruption in the system,” he added.

Standard TCP/IP protocol should also work seamlessly with the DTN, allowing planetary missions to have their own distributed Internet whilst using DTN as a link through interplanetary space.

This has obvious applications for future manned missions to Mars, after all, can you imagine the first colonists without their own blog?

Source: Technology Review