Ulysses spacecraft known for its resourcefulness

William Atkins
Tuesday, 15 January 2008 18:33

Science - Space

With the Sun beginning a new solar cycle (No. 24), the Ulysses spacecraft just happens to be at the right spot, at the right time: the solar North Pole.         

Launched in October 1990 onboard the space shuttle Discovery (STS-41)—as a joint mission of NASA and the European Space Agency (ESA)—Ulysses is in a 6.2-year heliocentric orbit that takes it periodically over the Sun’s north and south poles.

Ulysses is in an unique orbit about the Sun. It is inclined at about eighty degrees to the ecliptic plane (the plane in which most of the solar system’s planets, including Earth, reside as they orbit the Sun).

In other words, as the Earth moves around the Sun in one plane, Ulysses is moving around the Sun in a plane that is almost perpendicular to Earth’s plane.

At the start of this new solar cycle, Ulysses just happens to be in a position that will take it over the North Pole of the Sun at the beginning of this new cycle. Scientists are excited about learning more about solar cycles from this new trip around the North Pole of the Sun.

Ulysses is equipped with instruments that can measure magnetic fields and particles (such as electrons, neutral gas, dust, cosmic rays, and ions) in and around the Sun.

So far, the spacecraft has taken the first detailed measurements of the solar wind from the Sun’s polar areas at solar minimum (1994, south pole, and 1995, north pole) and solar maximum (2000, south, and 2001, north).

A 22-year solar cycle includes a period (about eleven years) of lowered magnetic activity (eventually reaching a minimum) and a period (about eleven years) of increasing magnetic activity (eventually reaching a maximum).