Ulysses spacecraft known for its resourcefulness

William Atkins
Tuesday, 15 January 2008 19:33

Science - Space

During the first orbit of the Sun’s poles in 1994-95, Ulysses discovered that the Sun’s magnetic poles were positive, with outward fields, in the north and negative, or inward fields, in the south. During its second orbit, the Sun’s polar fields disappeared and then reappeared with the opposite directions, negative (inward) in the north and positive (outward) in the south.

Ulysses also discovered that the amount of magnetic flux (a measure of the amount of magnetism) coming out of the Sun is pretty much equal at all latitudes on the Sun.

Scientists consider the two solar poles as very important when studying the solar cycle of the Sun. NASA Jet Propulsion Laboratory scientist Ed Smith, who is also the project scientist for the Ulysses project, states, according to a NASA website, “Just as Earth's poles are crucial to studies of terrestrial climate change, the sun’s poles may be crucial to studies of the solar cycle.”

Central to the solar cycle is sunspots and the poles themselves. Solar astronomers contend that the number of sunspots, their first appearance at the start of a new solar cycle, and where they go when they eventually break up has something very important to do with the solar cycle. When sunspots disintegrate their weakened magnetic fields are moved toward the poles by gigantic currents of plasma.

Once getting to the poles, they sink underneath the surface, possibly as far as 125,000 miles (200,000 kilometers) beneath the surface. Far inside the Sun, the sunspots are thought to be rejuvenated by the sun’s inner magnetic core.

Sunspots are regions in the Sun’s photosphere (the surface of the Sun) that contains temperatures lower than other areas. More magnetic activity occurs in these areas, which lowers the movement of its gases, thus, lowering its temperatures.

So, during the week of Monday, January 14, 2008, the Ulysses spacecraft will be measuring the Sun’s magnetic field over the North Pole during its voyage over the top of the Sun.

One interesting piece of mystery that Ulysses has found is that the North Pole is about 80,000 degrees cooler than the South Pole. Scientists do not know why this temperature difference occurs, but want to uncover the mystery.

Since this trip around the Sun's North Pole is coming very close to the February 2007 flyby of the South Pole, scientists are hoping to learn more about the magnetic field at the poles and why the North Pole is cooler than the South Pole.

Additional information about the Ulysses spacecraft is found at:

ESA: http://ulysses.esa.int/science-e/www/area/index.cfm?fareaid=11.

NASA/JPL: http://ulysses.jpl.nasa.gov/.