On the freezing surface of Mars, a sensor takes readings of the thin
atmosphere and transmits the data to an automated rover, which relays the
information to an orbiting satellite. From there, the data packets are sent to
an approaching research ship, where astronauts study the readings and send their
findings back to Earth, via e-mail.
Via e-mail?!
This may sound like science fiction, but it is becoming science fact. The Interplanetary Internet (IPN) has a growing number of proponents, including Vint Cerf, a co-designer of the TCP/IP protocol and who is often referred to as the "father of the Internet." The IPN would form a backbone connecting a series of hubs on or around planets, ships, and at other points in space. These hubs would provide high-capacity, high-availability Internet traffic over distances that could stretch up to hundreds of millions of miles.
IPN researchers have already assigned Internet addresses to all the planets, satellites, and spacecraft in our solar system. Scientists are hoping to launch a series of IPN-equipped satellites, possibly as soon as 2005. With one or more IPN-equipped satellites in orbit around Mars, we would have a two-planet IPN network.
NASA currently communicates with interplanetary and Earth-orbiting missions using its Deep Space Network. The network consists of dishes in California, Spain, and Australia, which are manually set to receive transmissions from a given spacecraft. The main drawback of the Deep Space Network is that it relies on line-of-sight transmissions. That means rovers or astronauts on the far side of Mars must wait until they are back in the line of sight with Earth before sending a message home. To receive the message, the Deep Space Network dishes must be pointed in the right direction at the right time, or the signal will be lost forever.
The IPN would work more like e-mail, where information would be stored and forwarded to any hub on the system. This "delay-tolerant" network would provide an always-on connection between planets, spacecrafts, and the terrestrial Internet. In the case of Mars, these hubs could be installed on a series of satellites circling the planet. Astronauts could send messages from the far side of Mars, and those messages would be relayed to the nearest hub for routing back to Earth. The "store-and-forward" methodology of the IPN helps minimize problems that crop up due to the vast distances involved, such as high error rates and latency rates that are minutes or even hours long (versus fractions of a second on Earth).
IPN researchers, including scientists from NASA’s Jet Propulsion Laboratory, the MITRE Corporation, UCLA, and the California Institute of Technology, have their eyes on the upcoming Mars Exploration Rovers (MERs), which are scheduled to launch in May and June of this year. The Rovers will be equipped with CCSDS (Consultative Committee for Space Data Systems) protocols that will eventually make up the IPN infrastructure. While the original plan called for the Rovers to have complete IPN software aboard, the code was "not mature early enough to be included in MERs’ advance mission planning," said Stephen Farrell, chairman of the IPN Special Interest Group.
Earth-bound Internet and cell-phone users won’t be surfing the IPN any time soon, but the research that goes into the interplanetary network could spark innovations in new or existing terrestrial networks. "That type of work usually does result in some relatively speedy commercial spin-offs," Farrell said.
Those looking to participate in this new frontier can do so in the Interplanetary Network Special Interest Discussion Group (
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