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NASA-European
Spacecraft Swoops Under Sun's Pole
February
07, 2007
The 16-year-old Ulysses
spacecraft reaches what could be considered a low point in its
mission observing the sun today - and solar scientists could not
be happier. The European-manufactured, joint NASA- and
ESA-managed spacecraft, has reached maximum latitude in its
exploration of the heliosphere, the bubble in space blown out by
the solar wind.
"At max latitude we are actually
passing below the sun looking almost directly up at its south
pole from 329 million kilometers (204 million miles) away,"
said Nigel Angold, Ulysses mission operations manager from the
European Space Agency. "The trajectory provides a
perspective of the sun no other spacecraft can equal."
This unusual perspective is courtesy of the spacecraft's
one-of-its-kind 6.3-year-long orbit around the sun. An orbit that
swings Ulysses both over and under the sun's polar regions and as
far out as the orbit of Jupiter.
"Max latitude is
the start of an important mission phase," said Dr. Ed Smith,
Ulysses project scientist at NASA's Jet Propulsion Laboratory,
Pasadena, Calif. "The spacecraft will soon begin
accelerating as it transits from below the sun's south pole to
its equator and then up and over its north pole. This trajectory
provides us a ringside seat to all the solar processes we want to
observe."
This phase of the mission is expected to
return high priority scientific observations revealing the
changing sun and its effect on space during the ongoing minimum
in the 11-year sunspot cycle. During this portion of the mission,
Ulysses will rapidly scan the sun's magnetic field, solar
plasmas, solar radio noise, energetic particles, galactic cosmic
rays and cosmic dust between the poles and the equator –
imparting a more complete perspective of the sun's atmosphere.
Understanding the Earth's nearest star and its processes
is paramount, as the space weather created by the sun has a huge
effect on the third rock from it and its inhabitants. The sun's
gaseous outer atmosphere can create huge space storms. This
violent space weather, in turn, can affect Earth's electrical
grid, cell phone communications, the functioning of satellites
and the operation of astronauts in orbit. This passage between
the sun's poles is the third in the 17 years of Ulysses
operations. The first transit occurred during the previous
sunspot minimum in 1994 to 1995, and the second during sunspot
maximum in 2000 to 2001. The opportunity to repeat the scientific
investigations during the ongoing solar minimum is important
because the sun’s magnetic field has changed significantly
since the previous minimum.
The Ulysses spacecraft was
carried into Earth orbit in the cargo bay of the Space Shuttle
Discovery on Oct. 6, 1990. From Earth orbit it was propelled
toward Jupiter by solid-fuel motors. Ulysses passed Jupiter on
Feb. 8, 1992; the giant planet's gravity bent the spacecraft's
flight path downward and away from the ecliptic plane. This put
it into a final orbit around the sun that would take it past the
sun's north and south poles.
The spacecraft was built by
Dornier Systems of Germany for the European Space Agency. NASA
provided the launch via space shuttle and the upper stage
boosters. The U.S. Department of Energy supplied a radioisotope
thermoelectric generator which powers the spacecraft; science
instruments were provided by both U.S. and European
investigators. The spacecraft is operated from JPL by a joint
team from the European Space Agency and NASA.
For More Information About
Ulysses, See Related Article: Ulysses
Still Going Strong
Source:
NASA
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