NASA's Voyager 1 spacecraft is about to become the first manmade object to enter interstellar space. All it has to do is cross one last stretch of space known as the magnetic highway.
"This strange, last region before interstellar space is coming into focus, thanks to Voyager 1, humankind's most distant scout," said Ed Stone, Voyager project scientist at the California Institute of Technology in Pasadena.
So far, NASA scientists see two of the three signs of interstellar space: charged particles that vanish as they travel the edge of our sun's magnetic field, and cosmic rays from the depths of space shooting in. The only one missing is a distinct shift in the magnetic field, which would indicate that Voyager 1 is now in the interstellar magnetic field, rather than our sun's.
"If you looked at the cosmic ray and energetic particle data in isolation, you might think Voyager had reached interstellar space, but the team feels Voyager 1 has not yet gotten there because we are still within the domain of the sun's magnetic field."
Voyager 1 was launched alongside Voyager 2 back in 1977, and as of Aug. 25 last year, Voyager 1 entered the magnetic highway that separates it from interstellar space. The Voyagers' missions are to probe further into space than any manmade object has gone before, and map out the heliosphere, the bubble of the sun's influence that surrounds our solar system.
"We saw a dramatic and rapid disappearance of the solar-originating particles. They decreased in intensity by more than 1,000 times, as if there was a huge vacuum pump at the entrance ramp onto the magnetic highway," said Stamatios Krimigis, from the Johns Hopkins University Applied Physics Laboratory in Laurel, Md. "We have never witnessed such a decrease before, except when Voyager 1 exited the giant magnetosphere of Jupiter, some 34 years ago."