More than 35 years after it launched on a mission to explore the cosmos, NASA's unmanned Voyager spacecraft appears to have left the solar system and is in a "new region" of space, said a study Wednesday.
If confirmed, the mission would mark the first man-made object ever to venture so far.
The Voyager 1 "appears to have traveled beyond the influence of the Sun and exited the heliosphere," or the magnetic bubble of charged particles that surround the solar system, said a statement on the American Geophysical Union's web site.
Findings that show a sharp change in cosmic ray activity, dating to August 25, 2012, have been accepted for publication in Geophysical Research Letters, a journal of the American Geophysical Union, it said.
Researcher Bill Webber, one of the article's authors, acknowledged that the actual location of the spacecraft -- whether in interstellar space or just an unknown region beyond the solar system -- remains a matter of debate.
"It's outside the normal heliosphere, I would say that," said Webber, professor emeritus of astronomy at New Mexico State University in Las Cruces, according to the AGU's web site.
"We're in a new region. And everything we're measuring is different and exciting."
NASA did not immediately respond to AFP requests for comment.
Voyager 1 and its companion Voyager 2 launched in 1977 on a mission to study planets. They have both kept going, and both are on track to leave the solar system, NASA has said.
For months, experts have been closely watching for hints that Voyager 1 has left the solar system and most have estimated it would likely happen in the next year or two.
NASA has described Voyager 1 -- now 11 billion miles (18 billion kilometers) away from the Sun -- and its companion Voyager 2 as "the two most distant active representatives of humanity and its desire to explore."