>From: "NASA Jet Propulsion Laboratory" <info@jpl.nasa.gov>
>Reply-To:
info@jpl.nasa.gov>Subject: Voyager Spacecraft Enters Solar System's Final Frontier
>Date: Tue, 24 May 2005 09:52:44 -0700
>
>MEDIA RELATIONS OFFICE
>JET PROPULSION LABORATORY
>CALIFORNIA INSTITUTE OF TECHNOLOGY
>NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
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>http://www.jpl.nasa.gov
>
>Jane Platt (818) 354-0880
>Jet Propulsion Laboratory, Pasadena, Calif.
>
>Dolores Beasley (202) 358-1753
>Headquarters, Washington
>
>Bill Steigerwald (301) 286-5017
>Goddard Space Flight Center, Greenbelt, Md.
>
>News Release: 2005-084 May 24, 2005
>
>Voyager Spacecraft Enters
Solar System's Final Frontier
>
>NASA's Voyager 1 spacecraft has entered the solar system's final frontier. It is entering a vast,
>turbulent expanse where the Sun's influence ends and the solar wind crashes into the thin gas between
>stars.
>
>"Voyager 1 has entered the final lap on its race to the edge of interstellar space," said Dr. Edward
>Stone, Voyager project scientist at the California Institute of Technology in Pasadena. Caltech
>manages NASA's Jet Propulsion Laboratory in Pasadena, which built and operates Voyager 1 and its
>twin, Voyager 2.
>
>In November 2003, the Voyager team announced it was seeing events unlike any in the mission's
>then 26-year history. The team believed the unusual events indicated Voyager 1 was approaching a
>strange region of space, likely the beginning of this new frontier
called the termination shock region.
>There was considerable controversy over whether Voyager 1 had indeed encountered the termination
>shock or was just getting close.
>
>The termination shock is where the solar wind, a thin stream of electrically charged gas blowing
>continuously outward from the Sun, is slowed by pressure from gas between the stars. At the
>termination shock, the solar wind slows abruptly from a speed that ranges from 700,000 to 1.5
>million miles per hour and becomes denser and hotter. The consensus of the team is that Voyager 1,
>at approximately 8.7 billion miles from the Sun, has at last entered the heliosheath, the region beyond
>the termination shock.
>
>Predicting the location of the termination shock was hard, because the precise conditions in
>interstellar space are unknown. Also, changes
in the speed and pressure of the solar wind cause the
>termination shock to expand, contract and ripple.
>
>The most persuasive evidence that Voyager 1 crossed the termination shock is its measurement of a
>sudden increase in the strength of the magnetic field carried by the solar wind, combined with an
>inferred decrease in its speed. This happens whenever the solar wind slows down.
>
>In December 2004, the Voyager 1 dual magnetometers observed the magnetic field strength suddenly
>increasing by a factor of approximately 2-1/2, as expected when the solar wind slows down. The
>magnetic field has remained at these high levels since December. NASA's Goddard Space Flight
>Center, Greenbelt, Md., built the magnetometers.
>
>Voyager 1 also observed an increase in the number of high-speed electrically charged electrons
and
>ions and a burst of plasma wave noise before the shock. This would be expected if Voyager 1 passed
>the termination shock. The shock naturally accelerates electrically charged particles that bounce back
>and forth between the fast and slow winds on opposite sides of the shock, and these particles can
>generate plasma waves.
>
>"Voyager's observations over the past few years show the termination shock is far more complicated
>than anyone thought," said Dr. Eric Christian, Discipline Scientist for the Sun-Solar System
>Connection research program at NASA Headquarters, Washington.
>
>The result is being presented today at a press conference in the Morial Convention Center, New
>Orleans, during the 2005 Joint Assembly meeting of Earth and space science organizations.
>
>For their original missions to Jupiter
and Saturn, Voyager 1 and sister spacecraft Voyager 2 were
>destined for regions of space far from the Sun where solar panels would not be feasible, so each was
>equipped with three radioisotope thermoelectric generators to produce electrical power for the
>spacecraft systems and instruments. Still operating in remote, cold and dark conditions 27 years later,
>the Voyagers owe their longevity to these Department of Energy-provided generators, which produce
>electricity from the heat generated by the natural decay of plutonium dioxide.
>
>For more information about Voyager visit:
>http://www.nasa.gov/vision/universe/solarsystem/voyager_agu.html and http://voyager.jpl.nasa.gov/ .
>
>For information about NASA and agency programs on the Internet, visit:
>http://www.nasa.gov/home/index.html .
>
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