NASA's latest mission will add a piece to its planned space Internet.
NASA launched the Mars Reconnaissance Orbiter last Friday, in part to lay the foundation for an Internet in outer space. Besides conducting basic science research, NASA officials say, the orbiter will become part of a high-speed telecommunications link between Earth and the Red Planet.
After the orbiter approaches Mars in 2006, it will join the Mars Global Surveyor and Mars Odyssey to create a three-node network, which could become a component of the InterPlanetary Internet.
But the orbiter is only the start of interplanetary information sharing, NASA officials say. The orbiter "is sort of a pathfinder in these next-generation reconnaissance missions as we continue to put people back on the moon and ultimately get them to Mars," said James Garvin, NASA's chief scientist.
The orbiter will locate routes for humans to travel and let other spacecraft piggyback on its enormous data-transmission capacity, Garvin said. Scientists expect the orbiter to beam back 34 terabits of data, the equivalent of 6,500 CDs' worth of information more than all previous Mars missions combined.
After scientists review the Mars orbiter's images and measurements for more than two years, the craft will continue orbiting for at least another two years. During this phase, it will become part of the InterPlanetary Internet for future Mars-bound spacecraft.
When humans land on Mars, they will need people on Earth to talk them through their activities and monitor their vital signs. But because it takes up to 20 minutes for an astronaut on Mars to get directions from Earth, NASA's mission control would face a 40-minute communications delay.
The InterPlanetary Internet is NASA's solution to that problem. It will be designed to overcome the speed-of-light delay in data transmission that has hung up space communications, NASA scientists say.
In addition, planetary bodies often block communications with orbiting satellites. With orbiters placed strategically across space, the InterPlanetary Internet will use standard "store and forward" techniques to transmit data across interplanetary distances.
Vinton Cerf, often referred to as the father of the Internet, began work on the InterPlanetary Internet in 1998. "We started out with the rather simple-minded idea that we could take the Internet and just make it run over longer distances," said Cerf, a distinguished visiting scientist at NASA's Jet Propulsion Laboratory (JPL) and senior vice president for technology strategy at MCI.
He has since discarded that notion as unfeasible and is focused on store and forward techniques and more powerful antennas on Earth. "There's been some serious consideration to creating a new system of antennae," Cerf said. Currently, NASA has three 70-meter antennas in California, Spain and Australia.
JPL is proposing a new system of antennas in which 12-meter dishes would be spaced, for example, about 20 meters apart from each other, Cerf said. This grouping of antennas would collect as much data as a 20-meter dish but would be more flexible. NASA could have antennas pointing in different directions, supporting multiple space missions, he said.
Some former NASA scientists say the government must spend more money on building antennas if the United States expects to send more vehicles into space.
"A lot of spacecraft are contending for time on the antennae," said Donna Shirley, former manager of the Mars Exploration Program and original leader of the team that built the Sojourner Rover. The Mars orbiter "is going to be collecting data like mad and just squirting it down to Earth every time it can see the Earth."