Voyager 1 leaves the solar system, NASA confirms

September 12, 2013|By Monte Morin, Los Angeles Times
  • Ed Stone, Voyager project scientist at Caltech, stands before a model of the spacecraft. On Thursday, Stone confirmed that Voyager 1 entered interstellar space more than a year ago.
Ed Stone, Voyager project scientist at Caltech, stands… (NASA )

This post has been corrected. See note below.

After 36 years of space travel and months of heated debate among scientists, NASA confirmed Thursday that Voyager 1 has indeed left our solar system and had entered interstellar space more than a year ago.

"Voyager has boldly gone where no probe has gone before, marking one of the most significant technological achievements in the annals of the history of science," said John Grunsfeld, NASA's associate administrator for the Science Mission Directorate.

At a Thursday news conference in Washington, D.C., officials said the belated confirmation was based on new "key" evidence involving space plasma density. The evidence was outlined in a paper published online Thursday in the journal Science, the Los Angeles Times reported.

Lead author Don Gurnett, a University of Iowa plasma physicist and a Voyager project scientist, said the data showed conclusively that Voyager 1 had exited the heliopause — the bubble of hot, energetic particles that surrounds our sun and planets — and entered into a region of cold, dark space called the interstellar medium. 


"When we got that data, I and my colleagues just looked at each other and said, 'We’re in the interstellar medium.' It was just that clear to us," Gurnett said.

Gurnett calculated that Voyager crossed the edge of the heliosphere, or heliopause, at or around Aug. 25, 2012.

"Even though it took 36 years, it's just an amazing thing to me," said study coauthor Bill Kurth, a radio and plasma researcher at the University of Iowa.

Scientists had begun to vigorously debate Voyager’s whereabouts earlier this year, when it was clear that the probe was being bombarded by an increasing number of galactic cosmic rays and that the number of high-energy particles from inside the heliosphere had plummeted.

However, NASA scientists said they could not be certain Voyager had left the solar system until surrounding magnetic fields changed direction. After waiting for that change for more than a year, however, officials conceded that the magnetic field change was not a necessary indicator.

“It’s a big surprise, and it's another mystery,” said Ed Stone, a Voyager project scientist at Caltech and former chief of the Jet Propulsion Laboratory in La Canada Flintridge. “This is not what our models were telling us. We have to address this issue, but right now ... we don’t understand.”

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