Almost two years ago, NASA announced that that the Voyager 1 spacecraft had departed the heliosphere and passed into interstellar space. New research now shows that the historic proclamation might have been premature, according to a press release issued by the American Geophysical Union.
Though there might have been multiple observations supporting the Voyager mission team's claim that it had indeed reached interstellar space, including data collected from a new "tsunami wave" generated by the sun earlier this month, some experts argue that the probe is still within the magnetic bubble surrounding the sun and planets.
They believe that it has not made its way to the space between the stars.
Two researchers working with Voyager 1 have created a test to show whether the spacecraft is inside or outside of the heliosphere.
The scientists predict that Voyager 1 will cross the current sheet at some point within the next two years, according to the release.
One that happens, Voyager team members should see a reversal in the magnetic field surrounding the probe, which would probe that it is still within the heliosphere.
If this change doesn't happen in the next two years or so, then Voyager is already in interstellar space, according to the researchers.
"The proof is in the pudding," George Gloeckler of the University of Michigan, lead author of the new study detailing the test, said in a statement, according to the release. "This controversy will continue until it is resolved by measurements."
Their test, which will be detailed in a future edition of Geophysical Research Letters.
"The nature of the scientific process that alternative theories are developed in order to account for new observations. This paper differs from other models of the solar wind and the heliosphere and is among the new models that the Voyager team will be studying as more data are acquired by Voyager," Voyager project scientist Ed Stone from the California Institute of Technology said in a NASA statement.
Stephen Fuselier, director of the space science department at the Southwest Research Institute in San Antonio, Texas, who is not involved with the research and is not on the Voyager 1 team, believes Voyager 1 has entered interstellar space, but said he will reserve judgment on whether Gloecker and Fisk are correct until 2016.
He added that while there is a sizeable fraction of the space community that is skeptical that Voyager 1 has entered interstellar space, the proposed test should help end the debate once and for all.
"If you go back 10 years and talk to the Voyager people, they would have told you 10 years ago that what they would see upon exiting the heliosphere is very, very different from what they are seeing now," Fuselier said. "We are just loaded down with surprises and this might be one of them."
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