Leave a Bread-Crumb Trail of Relays
Interplanetary communication, of course, isn't necessarily just about our own solar system. Since astronomers discovered the first planet orbiting a star similar to the sun in 1995, scientists have discovered scores of other exoplanets, as worlds outside our solar system are called [source: NASA]. In October 2012, they even discovered a planet roughly the size of Earth orbiting the star Alpha Centrauri B, which is in the closest neighbor system of stars, about 2.35 trillion miles (3.78 trillion kilometers) away [source: Betts].
That's a dauntingly huge distance, to be sure. But even so, some space scientists envision someday launching a giant starship that essentially would be a moving, self-contained miniature version of Earth, capable of sustaining successive generations of astronauts who would venture across interstellar space in an effort to reach other habitable planets and possibly even make contact with extraterrestrial civilizations.
Project Icarus, a recent effort by space scientists and futurists to come up with a blueprint for such a mission, pondered the problem of how such a ship would continue to communicate with Earth as it got further and further into the unknown. They came up with one intriguing solution: Along the way, the massive ship would periodically jettison empty fuel canisters equipped with signal relay equipment, forming a chain that would pass back messages from the spacecraft to Earth. "The idea is that with a chain of relays between Icarus and Earth, each 'hop' of the signal is a much shorter distance than the whole distance of several light years," Pat Galea, a British engineer who participated in the design project, wrote in 2012. "So we could, potentially, reduce the transmitter power requirement, or the antenna size on Icarus, or alternatively, increase the data rate that can be sent over the link" [source: Galea].