NASA has discovered that the spacecraft has entered a new region at the very edge of the solar system, one that scientists feel is the final area it must cross before reaching interstellar space.
Scientists are calling this region the “magnetic highway” because of the connection between our sun’s magnetic field lines and interstellar magnetic field lines. This connection allows lower-energy charged particles from inside the bubble of charged particles that the sun blows around itself to expand outward and allows the higher-energy particles from outside to flow inward. Before entering, the charged particles bounce around in all different directions.
Since the direction of the magnetic field lines has not changed, the Voyager team is still considering this region part of our solar system. Once Voyager 1 breaks through this area, it is predicted that the magnetic field lines will change.
"We believe this is the last leg of our journey to interstellar space. Our best guess is it's likely just a few months to a couple years away. The new region isn't what we expected, but we've come to expect the unexpected from Voyager," said Edward Stone, Voyager project scientist based at the California Institute of Technology in Pasadena, CA.
The video below is a set of animations displaying NASA’s Voyager 1 spacecraft exploring the new magnetic highway region of our solar system. These animations are based on data from the spacecraft’s cosmic ray instrument. The particles in the video are invisible to the human eye and are less abundant, but are exaggerated here in this demonstration.
In December, 2004, Voyager 1 crossed a point in space called the “termination shock.” Termination shock can be described as the point where solar wind (a thin stream of electrically charged gas blowing outward billions of kilometers from the Sun) drops abruptly as it begins to feel the effects of interstellar wind. Since then, it has been exploring the heliosheath, the heliosphere’s out layer. In this region, the solar wind slowed down and the intensity of the magnetic field began to increase.
On July 28, 2012, Voyager data from two onboard instruments that measure charged particles indicated that the spacecraft was entering the magnetic highway region. It entered a second time on August 25, 2012 and has since been stable in the environment. Data revealed that the magnetic field became stronger each time Voyager 1 entered the highway region, but the direction of the magnetic field lines did not change.
"The magnetic field data turned out to be the key to pinpointing when we crossed the termination shock. And we expect these data will tell us when we first reach interstellar space," said Leonard Burlaga, a Voyager magnetometer team member at NASA’s Goddard Space Flight Center in Greenbelt, MD.
Voyager 1, launched in 1977, is the most distant human-made object, about 11 billion miles away from the sun. Its signal takes approximately 17 hours to travel to Earth.