NASA Voyager 1 Encounters New Region in Deep Space

MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109 PHONE 818-354-5011
http://www.jpl.nasa.gov

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

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

News release: 2012-381 Dec. 3, 2012

NASA Voyager 1 Encounters New Region in Deep Space

The full version of this story with accompanying images is at:
http://www.jpl.nasa.gov/news/news.php?release=2012-381&cid=release_2012-381

PASADENA, Calif. -- 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 of these magnetic field lines 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. At least one of the spacecraft has 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. Caltech manages JPL for NASA. The Voyager missions are a part of NASA's
Heliophysics System Observatory, sponsored by the Heliophysics Division of the Science Mission
Directorate at NASA Headquarters in Washington.

For more information about the Voyager spacecraft, visit: http://www.nasa.gov/voyager and
http://voyager.jpl.nasa.gov .

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