GO TO: 2065 INTERPLANETARY INTERNET

Leave it to Vint Cerf to think a few light-years ahead of the rest of us mortals. One of the most celebrated tech architects of the last century - and now chief Internet strategist for MCI WorldCom - Cerf is deep in a project to move the Net into outer space.

No joke. The launchpads will be busy over the next decade with public and private missions aimed at Mars and other planets, the moon, asteroids, and deep space. Cerf, 56, recently joined a small team of engineers at NASA's Jet Propulsion Laboratory to begin sketching out a wireless communications network that would let all those space-based machines and - eventually - astronauts talk to one another. For example, rovers confined to a planet's surface could use a common standard to exchange data with spacecraft from other missions whizzing by. The project, dubbed Interplanetary Internet (IPN), calls for space probes and satellites to serve as Net gateways, conveying data packets to and from Earth and among themselves.

In 1973, Cerf cowrote a pioneering white paper on TCP, the transmission protocol that spawned modern Internet communication. These days, the devoted engineer, emailer, and Trekker is thinking a lot about a space infrastructure. "I realized it had taken 20 years for the Internet to take off: from 1973 to 1993," Cerf says. "So I wondered what I should be doing to prepare for our needs in the future. An interplanetary backbone was the answer." Early in 1998, Cerf shared a space-Net vision with Adrian Hooke, a JPL scientist who has been working since the early 1990s on adapting cheaper, more efficient Internet-like protocols for space missions. The two began working together, and not long after, more help came along: $500,000 in development funds from Darpa, the gov-tech think tank where Cerf did much of the early work on the Internet in the '70s.

After several decades, once there's enough hardware spinning around the solar system, IPN promises near-continuous communications from space, driving costs down and increasing bandwidth (an even more precious commodity outside Earth's orbit). Later on, Cerf envisions this interplanetary backbone plugging into our own terrestrial Net. Students might log on to watch a webcam-equipped rover tour the Martian landscape. Astronauts could send and receive email and download music or movies. "I'm not sure about games," adds Cerf, who currently donates about two days a month to IPN. "Keep in mind, a mission to Mars is three years. I would expect people to use IPN largely to email and send attachments, things like that. You'd want a lot of contact."

The future of this next-generation Net revolves quite literally around Mars: A series of probes, launched by the US and other countries, will gradually envelop the planet between now and 2040. The first missions, slated for 2001, 2003, and 2005, will launch satellites into Mars' orbit and soft-land surface rovers with more processing power and electricity-generating power than Mars Pathfinder's lander. As Cerf and fellow IPN project leader Hooke foresee it, each new piece of mission hardware will come equipped with an IPN address, a spiffy .mars domain name, and a special protocol permitting each to operate as a node along a packet-switched network.

Although IPN bears similarities to our own Net, it presents many engineering challenges. Explains Hooke: "Earth's Internet has a problem the one in space won't: gazillions of people trying to use it at once. Our problem isn't supporting so many users but communicating in a very weird, noisy, long-delay communications environment." Round-trip transmission time between Mars and Earth is 20 to 50 minutes, depending on the planets' distance from each other - and that can seem like eons when trying to download a Pearl Jam MP3. To increase transmission speed, Hooke is working on protocols that ensure more efficient deliveries, and he's improved two components of the wireless space backbone. First, the packet-delivery scheme won't clog the system by resending missing packets (a luxury our own IPv4 standard affords). Rather, IPN will keep track of arriving packets and request missing ones. Second, IPN's packet headers will probably consume one-tenth as much bandwidth as standard TCP/IP headers. Back on Earth, special gateways will translate between packets sent by IPN and conventional TCP/IP.

IPN will also suffer bandwidth shortages because of its weak signal. In general, radio waves become fainter at a rate proportional to the square of the distance traveled. With current technology and transmitting power, for example, a probe orbiting Mars sends data to Earth at up to 250 Kbps. For a ground-based rover such as Pathfinder (working in a dusty atmosphere and receiving less than half the power-generating solar radiation Earth does), the rates fall to less than 10 Kbps - mighty slow when compared with your garden-variety dialup. But Hooke hopes that using late-model Mars rovers - interlinked and capable of more transmission power - will, within a decade, boost IPN capacity to a few hundred Kbps from the Martian surface and as much as 1 Mbps from an "aerostationary" satellite in synchronous orbit.

Cerf is even more optimistic. (After all, he is a special technical adviser to Gene Roddenberry's Earth: Final Conflict.) By 2020, he says, "I expect to see optical communication rather than radio communication, in which case we might see hundreds of megabits-per-second capacity." He envisions, by 2040, "a collaborative, stable backbone of satellites" serving as IPN's nucleus.

Where does all this lead? For Cerf, who helped nudge the Net toward becoming a platform for commerce in its early days, IPN will trigger a new era in private space exploration. "We all know the Internet didn't explode until it became a commercial enterprise," he says. "Space communication will probably have the same characteristic." To succeed, the most ambitious commercial space ventures (such as Jim Benson's company, SpaceDev, which hopes to land on an asteroid and claim ownership of it within the next few years) will require sophisticated communications.

"Commercialization of assets off the planet would mutually reinforce the growth of interplanetary communication," Cerf says. "I talked to Benson last week; it's not totally nuts."

Cerf cheerily anticipates the challenge, whatever the outcome. "Some people argue we should solve all the problems on Earth before going off the planet, but that's like telling Lewis and Clark to stay put until the rest of the East was settled. No way."

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