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Ulysses
Spacecraft Flies Over Sun's North Pole
 Jan.
14, 2008: Consider it a case of exquisite timing. Just
last week, solar physicists announced the beginning of a new
solar cycle and now, January 14th, the Ulysses spacecraft
is flying over a key region of solar activity--the sun's North
Pole.
"This is a wonderful
opportunity to examine the sun's North Pole at the onset of
a new solar cycle, "says Arik Posner, NASA Ulysses program
scientist. "We've never done this before." [more]
Ulysses Continues its Journey over the Sun's Polar Caps
Third northern polar pass began November 30, 2007
 The
Ulysses spacecraft continues to go where no other spacecraft
has gone before, namely, over the Sun's poles to study the
Sun and Its Influence on the space environment. About a
year after Ulysses once again crossed into the Sun's south
polar cap, it has begun its journey over the north polar
cap. Previous spacecraft have remained near the Sun's equator
where the Earth and other planets are located, however,
Ulysses' orbit is perpendicular or highly inclined to all
other spacecraft orbits providing a unique perspective from
which to study the Sun and its effect on surrounding space.
Entry into the North Polar Cap is defined by the heliographic
(solar) latitude of + 70 degrees. Ulysses will now proceed
to its maximum latitude of 80 degrees and then return to
70 degrees in 15 March 2008 and exit the polar cap. Observations
of the solar wind, magnetic field, solar energetic particles
and cosmic rays obtained during this interval will be compared
with those obtained in the South Polar Cap earlier this
year in order to investigate differences, i.e., a North-South
asymmentry or temporal differences - associated with changes
on the Sun made evident by the network of in-ecliptic (solar
equatorial) heliospheric spacecraft.
Understanding solar activity is important not only because the Sun is an average star that is available for close scrutiny but because it has important consequences for Earth and its inhabitants as we continue to move into a new era of space-based technology and are able to send people into space and its hazards. Solar activity and the sunspots are driven by the solar magnetic field that changes dramatically over a 22-year cycle. During the first Ulysses orbit, the Sun’s magnetic poles were positive with outward fields in the north and negative or inward fields in the south. During Ulysses second orbit at sunspot maximum, the Sun’s polar fields disappeared and then reappeared with the opposite sense, negative or inward in the north and positive or outward in the south. In addition, the strength of the polar fields is now about one-half of what they were during the first orbit. Consequently, Ulysses is currently poised to investigate this changed magnetic field and its effect on the solar wind, galactic cosmic rays and the other constituents in space.
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