NASA Voyager 1 Probe Encounters New Region in Deep Space

Dec. 03, 2012

Dwayne Brown
Headquarters, Washington
202-358-1726
dwayne.c.brown@nasa.gov

Jia-Rui C. Cook
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-0850
jccook@jpl.nasa.gov


RELEASE: 12-416

NASA VOYAGER 1 PROBE ENCOUNTERS NEW REGION IN DEEP SPACE

WASHINGTON -- NASA's Voyager 1 spacecraft has entered a new region at
the far reaches of our solar system that scientists feel is the final
area the spacecraft has to cross before reaching interstellar space.

Scientists refer to this new region as a magnetic highway for charged
particles because our sun's magnetic field lines are connected to
interstellar magnetic field lines. This connection allows
lower-energy charged particles that originate from inside our
heliosphere, or the bubble of charged particles the sun blows around
itself, to zoom out and allows higher-energy particles from outside
to stream in. Before entering this region, the charged particles
bounced around in all directions, as if trapped on local roads inside
the heliosphere.

The Voyager team infers this region is still inside our solar bubble
because the direction of the magnetic field lines has not changed.
The direction is predicted to change when Voyager breaks through to
interstellar space. The new results were described at the American
Geophysical Union meeting in San Francisco on Monday.

"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. In this region,
the stream of charged particles from the sun known as the solar wind
abruptly slowed down from supersonic speeds and became turbulent.
Voyager 1's environment was consistent for about five and a half
years. The spacecraft then detected that the outward speed of the
solar wind slowed to zero.

The intensity of the magnetic field also began to increase at that
time.

Voyager data from two onboard instruments that measure charged
particles showed the spacecraft first entered this magnetic highway
region on July 28, 2012. The region ebbed away and flowed toward
Voyager 1 several times. The spacecraft entered the region again Aug.
25 and the environment has been stable since.

"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."

Spacecraft data revealed the magnetic field became stronger each time
Voyager entered the highway region; however, the direction of the
magnetic field lines did not change.

"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."

Voyager 1 and 2 were launched 16 days apart in 1977 and at least one
of the spacecraft visited Jupiter, Saturn, Uranus and Neptune.
Voyager 1 is the most distant human-made object, about 11 billion
miles (18 billion kilometers) away from the sun. The signal from
Voyager 1 takes approximately 17 hours to travel to Earth. Voyager 2,
the longest continuously operated spacecraft, is about 9 billion
miles (15 billion kilometers) away from our sun. While Voyager 2 has
seen changes similar to those seen by Voyager 1, the changes are much
more gradual. Scientists do not think Voyager 2 has reached the
magnetic highway.

The Voyager spacecraft were built and continue to be operated by
NASA's Jet Propulsion Laboratory, in Pasadena, Calif. The Voyager
missions are a part of NASA's Heliophysics System Observatory,
sponsored by the Heliophysics Division of the Science Mission
Directorate in NASA Headquarters in Washington.

For more information about the Voyager spacecraft, visit:

http://www.nasa.gov/voyager


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