The primary mission of the Ulysses spacecraft was to characterize the heliosphere as a function of solar latitude. The heliosphere is the immense magnetic bubble containing our solar system, solar wind, and the entire solar magnetic field. This vast region of interplanetary space is dominated by the ever-constant solar wind. The regions of primary scientific interest were at high latitudes – when Ulysses was at 70 degrees latitude or higher at both the sun’s north and south poles. Studies pre-dating Ulysses were limited to the ecliptic plane (that in which most of the planets orbit the sun), and no spacecraft had reached solar latitudes higher than 32 degrees. Ulysses launched in October 6, 1990, and in June 1994, began its four-month survey of the complex magnetic forces at work in the corona, or the sun’s upper atmosphere. It was the first mission to study the sun from both poles.
As a function of solar latitude, Ulysses investigated: the solar wind, structure of the sun/wind interface, the solar magnetic field, solar radio bursts and plasma waves, solar X-rays, solar and galactic cosmic rays, and both interstellar and interplanetary neutral gas and dust. In addition, Ulysses also studied comets and collected data on Jupiter’s immense magnetosphere as it flew by the giant planet on the way to its intended orbit. Ulysses made nearly three complete orbits of the sun.
Ulysses was a joint mission between NASA and the European Space Agency (ESA). ESA provided the spacecraft and operations team, while NASA oversaw launch, radio tracking, and data management operations. Ulysses ceased operations on June 30, 2009, after more than 18 productive years of charting the unexplored regions of the sun’s poles.