For over six months now, scientists have holding their breath, waiting for confirmation that the Voyager 1 spacecraft has left the solar system. In December 2012 NASA announced that the probe had entered a new region of space they dubbed the "magnetic highway." The region is one where charged particles can pass into and out of interstellar space, but scientists have been waiting for a large magnetic field shift to confirm Voyager's official exit.
This week, though, researchers at the University of Maryland are claiming that Voyager 1 has, in fact, already left the solar system. They have constructed a new model of the solar system that incorporates recent data from Voyager - one that places the probe outside the system as of last summer. Their observations appear in a new paper published this week in The Astrophysical Journal Letters.
"It's a somewhat controversial view, but we think Voyager has finally left the Solar System, and is truly beginning its travels through the Milky Way," said Marc Swisdak, lead author of the paper and a physicist at Maryland.
Swisdak and his colleagues have posited that Voyager's odd magnetic field ratings could be due to magnetic reconnection - a phenomenon closely related to high-energy events on the surface of the sun. They suggest that the region Voyager is currently in does not conform strictly with the sun's magnetic field, and is instead made up of "islands" of self-contained loops within the magnetic field. Swisdak also asserts that this new model can explain the rise in galactic particle counts Voyager has observed.
NASA, which still maintains that Voyager 1 is within our solar system, has responded to the new research. Though the current model NASA uses expects the interstellar magnetic field to have a different direction from the heliosphere, researchers with the agency will consider the new model.
"The fine-scale magnetic connection model will become part of the discussion among scientists as they try to reconcile what may be happening on a fine scale with what happens on a larger scale," said Ed Stone, a Voyager project scientist at the California Institute of Technology. "The Voyager 1 spacecraft is exploring a region no spacecraft has ever been to before. We will continue to look for any further developments over the coming months and years as Voyager explores an uncharted frontier.”
Whether it is currently inside or outside the sun's heliosphere, it now seems less likely that Voyager will get a grand, single-moment exit from our home system. Instead, it appears that the status of the spacecraft will be determined by good old-fashioned scientific research and debate.