In a new series of Q&A we’ll be reaching out to Icarus Interstellar consultants to gain their perspective on tough problems associated with interstellar flight. In this first Q&A we ask Dr Vint Cerf questions relating to interstellar communications.
Vinton G. Cerf is VP and Chief Internet Evangelist for Google. Cerf served at MCI, the Corporation for National Research Initiatives, at DARPA and as a member of the Stanford University Faculty. Cerf co-invented the architecture and basic protocols of the Internet. He has received the U.S. National Medal of Technology, ACM Turing award, the US Presidential Medal of Freedom and the Japan Prize. Vint Cerf served as chairman of the board of ICANN and as founding president of the Internet Society. He is a Fellow of the IEEE, ACM, and American Association for the Advancement of Science, the American Academy of Arts and Sciences, the International Engineering Consortium, the Computer History Museum, the National Academy of Engineering and a member of the American Philosophical Society. Cerf holds a BS degree from Stanford University and MS and Ph.D. degrees from UCLA. He has received eighteen honorary degrees. He is a Project Icarus Consultant.
Q. How does the interplanetary internet differ from the internet here on Earth?
A. Basically, the Delay and Disruption Tolerant Bundle Protocol (BP) is the interplanetary counterpart to the terrestrial Internet Protocol (IP).
The primary difference is that the BP is NOT expecting acknowledgements quickly AND assumes that bundles may be stored at intermediate nodes if the “next link” isn’t available immediately for transmission. The system is designed to cope with delays that could be hours or days or longer. BP works fine terrestrially and is very much like IP if the delays are low and bandwidths are high.
Q. Can the interplanetary internet be extended over interstellar distances?
A. We do not think so – at some point you have to be thinking about one-way transfers that are not really bidirectional. We would use a lot of forward error correction, block codes, etc for such communication. The other side would see us as a one-way destination too, at least from the protocol point of view.
Q. How could we cope with the challenges of getting as much data back through a (possibly) low bandwidth connection, while maintaining resilience against data loss due to interruptions?
A. The best tactic is to heavily code the data – see Digital Fountain methods as an example. http://en.wikipedia.org/wiki/Fountain_code
Q. Do you think there is scope for exploiting more exotic communication methods (e.g. gravitational lensing, quantum entanglement) for interstellar distances over the next ~100 years, or will we be sticking with direct RF and laser comms?
A. I think femto-second lasers may help (also looking at atto-second). Quantum entanglement is probably not going to help much over interstellar distances. Gravitational lensing may help to focus distant signals. I think lasercomm is the most likely path forward for the foreseeable future.
Q. Are you preparing for the fight over interstellar net neutrality?
A. Yes – although we have some concerns about Martian porn and what to do about it, especially since we are unable to recognize it when we see it.
For more fascinating conversations on interstellar research please attend Starship Congress, our conference on interstellar flight to be held in Dallas this August.