Imagine a future in which human intelligence is scattered all over the solar system. That intelligence may take the form of incredibly capable robots that allow us to be "telepresent" in remote parts of the solar system without ever leaving Earth, or perhaps remote space outposts on the Moon or Mars where human beings are learning to live on other worlds. In some of these places there may be thousands or millions of intelligent systems that need to exchange information not only with other intelligence on Earth but also among themselves. How would such communication occur, and how would it differ from the information transfer across the terrestrial Internet that we know so well?
We are all familiar with the explosive growth of the Internet, and the way in which it has entered our daily lives. We log on and expect to instantly access information from all over the world. This is enabled by a vast global network of computers that exchanges information over high-speed communications links. They do this by formatting messages to each other according to highly structured rules or protocols, much the same way that humans talk to each other using highly structured language. Supporting every web page download, every electronic-mail (e-mail) message, and every piece of streaming audio are dozens of computers that are chatting back and forth with each other in the background in order to transfer messages from the source to the destination. They accomplish this by breaking the messages themselves up into little "packets" of data that are routed over the Internet. This "chatty" computer dialog is very similar to a telephone call, where two people are simultaneously online and conducting a conversation.
But what happens when we try to extend the scope of the Internet into space? On Earth, electronic signals zip around the Internet at the speed of light with negligible delay and almost no errors because the distances are short and it is easy to provide strong signals. But as one ventures farther into space the distances become large and delays and errors are introduced. It would be very difficult to conduct a phone call between Earth and the Moon, where it may take five seconds for a signal to make the round-trip. At Mars, where the delay may easily be half an hour, it would be impossible. Furthermore, a continuous connection between Earth and a remote space location is very hard to provide—the radio links are noisy and prone to errors, spacecraft disappear behind the Sun for days on end, planets rotate, and spacecraft on and around them can only occasionally see Earth. The whole nature of communications changes—no longer chatty, with lots of instant feedback, but far more like the letter writing days of the Victorian era in the nineteenth century.
So will we ever be able to talk to other planets using the Internet? The answer is yes, and a small team of engineers at the California Institute of Technology's Jet Propulsion Laboratory in Pasadena, California—the National Aeronautics and Space Administration's lead center for deep-space exploration—is making it happen. New communications protocols are under development that form messages into autonomous "bundles" of information—much like letters or e-mail—that will allow human or robotic users all over the solar system to exchange information across the vast and hostile distances of space even though they may never be simultaneously connected. Deployment of these new capabilities will begin during the period of intensive Mars exploration in the early twenty-first century. The Interplanetary Internet is just around the corner.
see also Communications, Future Needs in (volume 4); Living on Other Worlds (volume 4); O'Neill Colonies (volume 4); Settlements (volume 4); Space Stations of the Future (volume 4); Telepresence (volume 4).
Adrian J. Hooke