Guest post by Vint Cerf, vice president and chief Internet evangelist at Google.
In a recent blog, Dr. Brennan correctly identified a future issue: access to medical information from a Mars colony, should one be established. In her summary, she said there was no internet in space.
Actually, there is.
It uses a protocol suite other than the terrestrial TCP/IP originally designed by Bob Kahn and me beginning in 1973 and which has evolved over time thanks to the work of the Internet Engineering Task Force and many researchers and internet practitioners around the world.
The Interplanetary Internet (sometimes called the Solar System Internet by the UN’s Consultative Committee on Space Data Systems) adopted a suite of protocols known generally as the Bundle Protocols. The prototypes of these protocols are on board the Mars rovers, Spirit and Opportunity, the Mars Science Laboratory, and the International Space Station.
The rovers and Science Laboratory use the Bundle Protocols to deliver their data to Earth by way of re-programmed orbiters initially sent to Mars to map the surface of the planet. In essence, the rovers and Science Laboratory capture sensor data, which they beam to the orbiter(s) as the orbiter(s) become visible. The orbiters then hold that data until they can be transmitted to Earth by way of the Deep Space Network (DSN), which was put into operation in the early 1960s to support manned and robotic space exploration. This transmit-and-hold approach of the Bundle Protocols is representative of Delay and Disruption Tolerant Networking (DTN).
The Deep Space Network has three 70-meter dishes located at Canberra, Australia; Madrid, Spain; and Goldstone, California. There are also several 34-meter dishes at these same locations. The DSN is operated by the Jet Propulsion Laboratory in Pasadena, California, under the oversight of the California Institute of Technology. These large dishes allow the Jet Propulsion Laboratory to receive very weak signals from spacecraft very distant from Earth. The Voyager spacecraft, Voyager 1 and Voyager 2, are now respectively 20.7 billion kilometers and 17 billion kilometers away from Earth and into interstellar space. The DSN can still read the very, very weak signals from both spacecraft.
If a plan does indeed emerge to assure that relevant information from the National Library of Medicine is available to Mars astronauts and perhaps colonists, the natural preparatory step would be to outfit the NLM online systems with Bundle Protocol capability. But don’t expect any kind of real-time, interactive World Wide Web-like service for Mars residents. The light speed round-trip times between Earth and Mars vary from 7 minutes to 40 minutes, and the data rates between Earth and Mars currently run less than 1 Mb/s using conventional radio communications. Experiments have been conducted using laser communications between Earth and the Moon at 600 Mb/s, so one might hope for significant data rate improvements in the future.
If humanity is to become a space-faring species, it will need continuing access to the scientific and medical advances cataloged in the NLM’s systems. We can certainly imagine putting up local data servers on Mars for rapid local interaction while updating these local archives from Earth NLM periodically.
InterPlanetary Networking Special Interest Group