A team of scientists has provided an explanation as to why NASA's Voyager 1, when it became the first probe to enter interstellar space in mid-2012, observed a magnetic field that was inconsistent with that derived from other spacecraft observations.
Voyager 1 sent back several different indications that it had punched through the edge of our sun's massive protective bubble inflated by solar wind, the heliosphere, after a 35-year journey. But the magnetic field data gathered by the spacecraft was not what scientists had expected to see. The University of New Hampshire study resolves the inconsistencies.
There are still naysayers out there regarding Voyager 1 crossing through the heliopause, the edge of the heliosphere and the reason for this doubt is that when the spacecraft supposedly broke through the heliopause, researchers should have seen some sort of distinctive shift in the magnetic field from one medium to the other, says lead author Nathan Schwadron.
Adding to the mystery, researchers found that the magnetic field direction observed in local interstellar space deviated by an angle of more than 40 degrees from what was expected. Some scientists posited that this deviation was an indication of Voyager 1 still being embedded in the solar wind inside the heliopause.
Schwadron and colleagues solved the discrepancies using triangulation of four different datasets gathered by other spacecraft, including the Interstellar Boundary Explorer (IBEX) mission that in 2009 discovered a mysterious "ribbon" of energy and particles believed to be associated with the interstellar magnetic field.
The scientists discovered that Voyager 1--like an orienteer through the outer solar system-measures the magnetic field moving the needle on a compass with cardinal directions provided by the IBEX ribbon. The ribbon center is the direction of "true magnetic north" for the pristine interstellar magnetic field.
With the recent discovery, scientists now know they'll need to wait at least another decade before Voyager enters the region of interstellar space that is beyond the reach of the sun. Since the dawn of the space age, humankind has never passed through and explored this far-flung, pristine environment.
The study is published in the Astrophysical Journal Letters.
