NASA confirms Voyager 1 has left the solar system

NASA confirms Voyager 1 has left the solar system,0,6990209.story
By Monte Morin
September 12, 2013, 11:00 a.m.
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. Lead author Don Gurnett, an Iowa State 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.
wide V shape. The antennas, which are connected to a radio transmitter, detect the oscillation, or vibration, of excited plasma particles. The device will convert the oscillations into an audible noise that is recorded on Voyager’s vintage eight-track tape recorder.
The frequency of the noise is associated with a specific density of plasma. The higher the frequency, the denser the plasma.
The only trouble is that something has to excite the plasma for it to “ring,” something like a large solar flare. Waiting for a solar flare can take years during a solar minimum (a period of low solar activity).