The U.S. space agency confirmed Voyager, launched in 1977 and now 12 billion miles from the sun, has transited the heliopause, the theoretical boundary separating the sun's solar wind of particles from the similar interstellar wind.
A report on an analysis of new data suggesting Voyager has been traveling through plasma, or ionized gas, present in the space between stars, was published Thursday in the journal Science.
"Now that we have new, key data, we believe this is mankind's historic leap into interstellar space," Ed Stone, Voyager project scientist based at the California Institute of Technology in Pasadena, Calif., said. "The Voyager team needed time to analyze those observations and make sense of them. But we can now answer the question we've all been asking -- 'Are we there yet?' Yes, we are."
Voyager has been sending data to Earth throughout its 36 years in space, during which it flew by Jupiter and Saturn.
Currently, the dim signal -- about 23 watts, the power of a refrigerator light bulb -- takes 17 hours to reach Earth even traveling at the speed of light.
"The team's hard work to build durable spacecraft and carefully manage the Voyager spacecraft's limited resources paid off in another first for NASA and humanity," Suzanne Dodd, Voyager project manager at NASA's Jet Propulsion Laboratory in Pasadena, said. "We expect the fields and particles science instruments on Voyager will continue to send back data through at least 2020.
"We can't wait to see what the Voyager instruments show us next about deep space."