Spacecraft usually communicate directly with Earth - the first to do so through an intermediary were the Mars Explorations Rovers, which launched in 2003. The Spirit and Opportunity rovers transmit data to orbiters, which then send the data back to Earth.
But human intervention is still required to schedule communications sessions for orbiters and Landers. "The traditional method of operations is largely manual," says Jay Wyatt of NASA's Jet Propulsion Laboratory in Pasadena, California. "People get in a room and decide when they can send data."
A new method would automate and streamline this process by sending data through an interplanetary 'internet'. Just as data is sent from one point to another on the internet via a linked network of hubs, or nodes, spacecraft scattered throughout the solar system could be used as nodes to transmit data through space.
Last week, NASA completed a month-long test of a simulated network of Mars Landers, orbiters and mission operations centers on Earth.
For the test, dozens of images of Mars and its moon Phobos were transmitted back and forth between computers on Earth and NASA's Deep Impact spacecraft. The craft, which sent an impactor into Comet Tempel 1 in 2005, has been renamed "Epoxi" now that it its mission has been extended to search for extrasolar planets.