PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011

Contact: Diane Ainsworth                 October 26, 1995

ULYSSES OFFERS NEW INSIGHTS ON CONDITIONS OVER SUN'S POLES

     After a journey of more than 3 billion kilometers (2 billion 
miles), the Ulysses spacecraft has completed the first pole-to-
pole passage over the Sun, showing scientists some of the solar 
forces at work in high latitude regions never before explored.   

     Scientists on the international NASA/European Space Agency 
mission gathered at Dana Point, CA this week for a 2-1/2-day 
workshop at which they compared notes on results from the 
spacecraft's first complete solar orbit and presented preliminary 
results of Ulysses' recently completed pass over the Sun's 
northern pole. 

     "This has been an exceptional journey to explore regions of 
the Sun never visited by spacecraft before," said Willis Meeks, 
U.S. project manager at NASA's Jet Propulsion Laboratory. 
"Spacecraft data over the polar regions of the Sun are allowing 
scientists to begin assembling the first three-dimensional 
picture of the heliosphere ever compiled."

     Several scientists from the Ulysses team explained the 
mission's results in a panel discussion that aired today on NASA 
Television. They included Dr. Edward J. Smith, U.S. project 
scientist at JPL and a co-investigator on the magnetic fields 
experiment; Dr. John Phillips of Los Alamos National Laboratory, 
principal investigator on the solar wind plasma experiment; Dr. 
Antoinette Galvin, University of Maryland, a co-investigator on 
Ulysses who also works with x-ray images of the Sun from the 
Japanese Yohkoh mission; Dr. Richard Marsden, ESA project 
scientist and a co-investigator on the cosmic rays and solar 
particles experiment; and Dr. J. R. Jokipii, an interdisciplinary 
scientist from the University of Arizona.

     Over the course of its five-year journey, Ulysses confirmed 
some theories about the Sun and found a few surprises, the 
scientists reported:
 
     -- Ulysses verified global differences in solar wind 
velocity, composition and temperature.

     -- The spacecraft saw outward-propagating, high-speed and 
long-period Alfven waves continuously in the high-speed solar 
wind over both poles of the Sun. (Alfven waves are waves which 
move along magnetic field lines and accelerate charged 
particles.) 

     -- An increase in magnetic field intensity in the polar 
regions was not seen, as was expected.  Instead, Ulysses found a 
uniform magnetic field whose intensity did not change from 
equator to pole.

     -- The theoretical "cosmic ray funnel," which would allow 
easy access of cosmic ray particles into the polar region, was 
not found.  Only a slight increase in cosmic ray intensity was 
seen over the pole.

     With its northern pass completed, Ulysses will begin to 
journey back out to the orbit of Jupiter.  The spacecraft will 
reach the giant planet's distance of 5.4 astronomical units 
(about 800 million kilometers or 500 million miles) on April 17, 
1998.  Once there Ulysses will loop back and return, this time 
arriving in the vicinity of the Sun during its most active 
sunspot phase.
 
     "The Sun will be near solar maximum in the fall of 2000 and 
the solar magnetic field will have reversed polarity," said Dr. 
Edward J. Smith, Ulysses project scientist at JPL. "We expect the 
profile we obtain five years from now will be dramatically 
different and give us many new insights into the dynamics of this 
star at the center of our solar system."    
     
     Based on the importance of its investigations and the 
excellent condition of the spacecraft, the Ulysses mission will 
continue through a second set of polar passes beginning in 
September 2000.  At the conclusion of its mission in December 
2001, the spacecraft will have collected data on solar phenomena 
at all latitudes during the quietest and most active phases of 
the 11-year solar cycle.

     The Ulysses mission is an international project of the 
European Space Agency and NASA to explore regions of space above 
and below the Sun's poles. The Jet Propulsion Laboratory manages 
the U.S. portion of the mission for NASA's Office of Space 
Science, Washington, D.C. 

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10/26/95 DEA
#9575




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