NASA's Voyager crossing 'magnetic highway' en route to interstellar space

NASA's Voyager 1 spacecraft has encountered a new region on the outskirts of our solar system that appears to be a magnetic highway for charged particles, the Johns Hopkins Applied Physics Laboratory announced today. Scientists believe this is the final region Voyager has to cross before reaching interstellar space, or the space between stars.

Scientists call this region the magnetic highway because our sun's magnetic field lines are connected to interstellar magnetic field lines. The connection has allowed lower-energy charged particles that originate from inside our heliosphere—the bubble of charged particles the sun blows around itself—to zoom out, and higher-energy particles from outside to stream in.

Before entering this region, the charged particles bounced around in all directions, as if trapped on local roads inside the heliosphere. Thinking the particles might be colliding against the gaseous boundary of the solar system, scientists operating Voyager's low-energy charged particle detector wondered if the spacecraft had reached the last stop before—or even crossed into—interstellar space. Data indicating that the direction of the magnetic field lines has not changed, however, leads the Voyager team to conclude that this region is still inside the solar bubble.

The results will be described today at the American Geophysical Union meeting in San Francisco.

"If we were judging by the charged-particle data alone, I would have thought we were outside the heliosphere," says Stamatios Krimigis, principal investigator of the Low-Energy Charged Particle instrument, based at the Applied Physics Laboratory in Laurel, Md. "In fact, our instrument has seen the low-energy particles taking the exit ramp toward interstellar space. But we need to look at what all the instruments are telling us and only time will tell whether our interpretations about this frontier are correct. One thing is certain—none of the theoretical models predicted any of Voyager's observations over the past 10 years, so there is no guidance on what to expect."