After Voyager 2's Neptune encounter, NASA renamed the Voyager project the Voyager Interstellar Mission. Most of the instruments on both spacecraft were permanently deactivated, with solar wind-related instruments kept operating to characterize the sun's waning influence. In December 2004, Voyager project scientist Ed Stone announced that Voyager 1 had passed through the 'termination shock,' where the solar wind abruptly slows to subsonic speeds. It was 94.01 astronomical units from the sun. (Earth is one astronomical unit from the sun.)
In August 2006, Voyager 1 reached 100 astronomical units from the sun, or about 15 billion kilometers (about 9.3 billion miles) from the sun. Voyager 2 was about 11 billion kilometers (about 7 billion miles) from the sun. Both craft are healthy and continue to send data back to Earth. In the next ten years, scientists expect the Voyagers to cross the heliopause, the edge of the bubble created by the solar wind, and become the first craft to reach interstellar space.
Artist concept showing Voyagers approaching interstellar space. + Full image