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A science blog with Eric Berger
More evidence that Voyager has exited the solar system
Friday, October 5, 2012
Something very, very interesting is happening with Voyager 1, the human probe that’s the very farthest from Earth.
New data from the spacecraft, which I will discuss below, indicate Voyager 1 may have exited the solar system for good. If true, this would mark a truly historic moment for the human race — sending a spacecraft beyond the edge of our home solar system.
At last check, NASA scientists said they were not yet ready to officially declare that Voyager 1 had officially exited the solar system by crossing the heliopause.
To cross this boundary scientists say they would need to observe three things:
1. An increase in high-energy cosmic rays originating from outside our solar system
2. A drop in charged particles emanating from the sun.
3. A change in the direction of the magnetic field.
As I reported in June, in regard to the first point, scientists have observed a sustained increase in galactic cosmic rays during recent months.
More galactic cosmic rays are striking Voyager 1. (NASA)
With respect to the second point, there has been a dramatic and sustained drop in charged particles (principally protons) originating from the Sun that have struck the spacecraft.
And by dramatic, I mean dramatic. Here’s how it looks:
Rate at which Voyager 1 is being bombarded by particles such as protons. (NASA)
I have reached out to Edward Stone, the Voyager project scientist based at the California Institute of Technology, who has oversight of the mission. He has not responded to my query about whether this means Voyager has truly exited the system.
The third question is whether the magnetic field affecting Voyager has changed. That data is not yet definitive, said Dave McComas, a heliopause expert with the Southwest Research Institute. “In the end, the magnetometer data will have to tell us if Voyager1 has crossed the heliopause or the disconnection boundary,” McComas told me.
Schematic of the Voyagers and the heliopause. (McComas and Schwadron, ApJ)
However Nick Suntzeff, a Texas A&M University astronomer, said based upon the stunning drop in charged particles, something is definitely happening to Voyager that NASA should be commenting upon:
“Even without the magnetometer data, the Voyager 1 data shows that it has gone through a huge barrier at the edge of the solar system. These guys are defining it based on their theory which requires a transition zone where the magnetic fields decouple. Maybe this is true. But the fact remains that the satellite has gone through a discontinuity in cosmic ray fluxes that is incredible. It is interacting with the boundary of the Solar System. I think that the data stand on their merit – something wonderful ( a line from the movie 2010) has happened”
Which is to say that NASA may be making an important announcement about Voyager 1 in the not too distant future.http://blog.chron.com/sciguy/2012/10/more-evidence-that-voyager-has-exited-the-solar-system/