LA CANADA FLINTRIDGE - It hasn't exited the solar system yet, but Voyager 1 is still surprising scientists as it travels farther than any other man-made object.
The spacecraft has entered a new region of space about 11 billion miles away from the sun, dubbed the magnetic highway, which is probably the last layer of the sun's sphere of influence before reaching interstellar space, JPL announced Monday.
"This is a very exciting time when we see things we didn't expect and which give us new puzzles," said Voyager project scientist Ed Stone, who has worked on the mission since it began 35 years ago. "That's what makes the science from Voyager so interesting. We seem to have this highway along which the particles inside have escaped and where the cosmic rays from outside have come in."
Voyager 1 is at the outer boundary of the heliosphere, a bubble of charged particles blown by solar winds. Recent data shows much of the environment around the spacecraft has changed, as particles speed up and escape. Scientists got a hint of the new region in July, and Voyager 1 crossed the boundary into it on Aug. 25.
Measurements of the sun's east-west magnetic field haven't changed, however, so scientists are confident that the spacecraft remains within the heliosphere. Interstellar magnetic field lines run north-south, and the highway is created because the magnetic lines are intersecting with the sun's east-west lines.
"If we had only looked at particle data alone, we would have said `well, we are out.
Voyager 1 and its twin, Voyager 2, launched in 1977 on a mission to visit the outer planets, eventually flying by Saturn, Jupiter, Uranus and Neptune. Both also carry the Golden Record, a collection of sounds and images from Earth available for any intelligent life that may come across the spacecrafts in the future.
Stone, a Caltech professor, said it's difficult to predict when Voyager 1 might break through because the new region was a complete surprise. Previously layers of the heliosphere took about two years to traverse, but he wouldn't be surprised if the magnetic highway is shorter.
"I don't know how long it will take, it could take several more months, it could take several more years," Stone said.
Voyager 2 is also nearing the edge of the heliosphere at a different route, but is lagging behind its twin by about a couple of billion miles.
The plutonium power sources on the spacecraft will only last until 2025 before the instruments must be shut off and their connections to Earth severed. After that, it could be a long time before either Voyager encounters anything exciting. It will take about 40,000 years for Voyager 1 to come close to another star.