The era of networked space communications is slowly dawning across NASA. Up until now, sending commands to a lonely ship was simply a matter of shooting off a radio signal when its antenna came within range. A simple matter, that is, after telecommunications software written precisely for that one specific mission had been painstakingly fashioned. Afterward, that software was usually discarded. For the next mission, unique software was crafted all over again.

Here's an idea: why doesn't NASA put a network in the sky, with each orbiter, rover, space-borne telescope, and any other skyward-launched device working as a node? Why not internetwork space? In fact, why not use the existing Internet?

Over the next several decades, as we embark on the next stage of the Internet's spread into our solar system, scientists will need to manipulate sophisticated experimental instruments on space stations and exchange vast streams of data with colleagues living on the moon and, eventually, Mars. The network that NASA will soon build could very well be the one over which scientists work out startling details of Martian geology, oceanic conditions under the ice of Jupiter's frigid moon Europa, or the turbulent cloud cover of Venus. It may well be the way a homesick space explorer sends e-mail back home.

If there were network links to remote probes, scientists could dial in to them as easily as they check the latest CNN.com headlines. All the information generated aboard these vehicles and habitats, from humdrum experiments growing crystals in zero gravity to data showing the existence of fossils of ancient microbes, could come in via a single network extending through the vacuum of space--not just from NASA, but from the European Space Agency, China's National Space Administration, and other organizations as well. So as we move from space discovery to exploration, and perhaps even extraterrestrial settlements, space engineers have begun to radically rethink how mission controllers could best communicate with Earth's far-flung emissaries.

Everyone at NASA agrees that extending the Internet to other planets would be ideal. Whether it's possible, however, and how, has become a source of fractious contention within the agency. Two different cliques have very different ideas about how this should be done.

One team of very smart researchers, most of them working at the Goddard Space Flight Center, in Greenbelt, Md. [see photo, ], is testing ways to use the basic networking protocols that run the Internet. That would let space scientists use all the tools they use on Earth today: Web browsers, file-transfer software, and so on. Using off-the-shelf hardware, as well as reusing existing earthbound software, would save money and development time.

As enthusiastic as these researchers are, another group within NASA has concluded that using Internet protocols in space--at least in deep space--will never work. Like the Goddard group, this camp has some very smart people on its side, including, surprisingly enough, Vinton G. Cerf, an IEEE Fellow who helped write the Internet protocols still used by the billions of computers and other devices on the Internet. According to Cerf and these other NASA researchers, Internet-style chatting with a shuttle 600 kilometers away may be easy enough, but wirelessly conversing with, say, Mars-orbiting craft 200 million km away is an essentially impossible challenge.

What started as a theoretical dispute within NASA is now a practical one, with a hard timetable. In January 2004, the Bush administration announced an ambitious new mission for NASA. It includes a successor to the space shuttles, called the Crew Exploration Vehicle, which is to run its first manned mission in 2014. Also in line are a series of robotic missions to the moon, beginning in 2008.

Once made, a protocol decision may have a lifetime longer than Pluto's year. The current Internet protocols are based on principles Cerf sketched out on the back of an envelope more than 30 years ago in a San Francisco hotel lobby. NASA has about a year to make network architecture choices that could bind the solar system for decades to come.