(-10-) Date: 10 March 1995
Subject: Ulysses Passes Perihelion
From: NASA Space News
ULYSSES SPACECRAFT MAKES CLOSEST APPROACH TO SUN
The Ulysses spacecraft will cross the Sun's equator March 12 and make
its closest approach to that body on its way to the northern polar
region of the Sun.
The spacecraft will pass within 200 million kilometers (124 million
miles) of the Sun at 11:40 Universal Time (3:40 a.m. Pacific Standard
Time), the closest it has ever been or ever will be to the Sun since it
was launched on October 6, 1990, said Donald Meyer, Ulysses deputy
mission operations manager at NASA's Jet Propulsion Laboratory.
Distance from Earth at perihelion, or closest approach to the Sun, will
be approximately 346 million kilometers (215 million miles).
Ulysses is crossing rapidly into the northern hemisphere now, traveling
at a rate of about 0.8 degrees in latitude per day and a velocity of
approximately 117,000 kilometers per hour (73,000 miles per hour), with
respect to the Sun.
For the last month the spacecraft has been collecting data on the
equatorial region of the Sun. This will continue for the next month,
until Ulysses begins to see features from the northern hemisphere of
the Sun, said Peter Beech, mission operations manager from the European
Space Agency.
All spacecraft operations and science experiments continue to go well.
A radio science experiment is currently under way to measure the
electron content of the Sun's fiery outer atmosphere, called the
corona, as Ulysses passes in back of the Sun as seen from Earth.
The S-band transmitter was turned on February 22 to take advantage of
Ulysses' unique position in space for the radio experiment. This
transmitter, in conjunction with the X-band transmitter, will be
beaming signals through the corona to provide measurements of the
electron content through March 15.
As Ulysses crosses into the northern hemisphere of the heliosphere --
the region of space dominated by the forces of the solar wind -- it
will begin its next phase of the primary mission to study that region
at all solar latitudes.
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- T o d d E. V a n H o o s e a r -
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