NASA Voyager 1 a Step Closer to Interstellar Space

First Posted: Dec 04, 2012 06:14 AM EST

NASA's Voyager 1 spacecraft has encountered a new region in deep space that gets it one step closer to the interstellar space.

Launched in 1977, Voyager 1 is the most distant human made object, about 11 billion miles away from the Sun, and takes 17 hours to travel to Earth. The spacecraft provided remarkable images of Jupiter, Saturn and their moons more than 30 years ago.

Voyager 1 has entered into a region that is referred to as a magnetic highway for charged particles. The reason is because the Sun's magnetic field lines are connected to interstellar magnetic field lines and this connection allows lower-energy charged particles that originate from inside heliosphere to zoom out and allow higher-energy particles from outside to stream in. The charged particles bounce back before entering into this region.

The Voyager team concludes this region is still inside the solar bubble because the direction of the magnetic field lines has not changed.  The direction may alter when Voyager breaks through to interstellar space. 

"Although Voyager 1 still is inside the Sun's environment, we now can taste what it's like on the outside because the particles are zipping in and out on this magnetic highway," said Edward Stone, Voyager project scientist based at the California Institute of Technology, Pasadena. "We believe this is the last leg of our journey to interstellar space. Our best guess is it's likely just a few months to a couple years away. The new region isn't what we expected, but we've come to expect the unexpected from Voyager."

Since December 2004, when Voyager 1 crossed a point in space called the termination shock, the spacecraft has been exploring the heliosphere's outer layer, called the heliosheath. 

From the onboard instruments that measure charged particles, the voyager's data is received. It was July 28, 2012 that the spacecraft first entered this magnetic highway region.

"If we were judging by the charged particle data alone, I would have thought we were outside the heliosphere," said Stamatios Krimigis, principal investigator of the low-energy charged particle instrument, based at the Johns Hopkins Applied Physics Laboratory, Laurel, Md. "But we need to look at what all the instruments are telling us and only time will tell whether our interpretations about this frontier are correct."

Each time the Voyager entered the highway region, the magnetic field became stronger without any changes in the direction.

"We are in a magnetic region unlike any we've been in before -- about 10 times more intense than before the termination shock -- but the magnetic field data show no indication we're in interstellar space," said Leonard Burlaga, a Voyager magnetometer team member based at NASA's Goddard Space Flight Center in Greenbelt, Md. "The magnetic field data turned out to be the key to pinpointing when we crossed the termination shock. And we expect these data will tell us when we first reach interstellar space."

The new results were described at the American Geophysical Union meeting in San Francisco, Monday.

See Now: NASA's Juno Spacecraft's Rendezvous With Jupiter's Mammoth Cyclone

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