Voyager 1: Is It In or Is It Out?

Nearly 18.7 billion kilometers from Earth -- about 17 light-hours away -- NASA's Voyager 1 spacecraft is just about on the verge of entering interstellar space, a wild and unexplored territory of high-energy cosmic particles into which no human-made object has ever ventured. Launched in September 1977, Voyager 1 will soon become the first spacecraft