What came before IBEX?
In the late 1970s and 1980s, the Voyager spacecraft expanded our knowledge of the outer Solar System. Voyagers 1 and 2 both explored the planets Jupiter and Saturn, and Voyager 2 explored Uranus and Neptune. After their planetary observations, both spacecraft continued outward in different directions. The Voyagers were only supposed to last a few years, but they have continued to operate for over 30 years, well past their designed lifetimes. Today, both Voyagers are taking direct measurements of the magnetic fieldA field of force that is generated by electric currents. The Sun's average large-scale magnetic field, like that of the Earth, exhibits a north and a south pole linked by lines of magnetic force. strength and the speed of the solar wind plasmaPlasma consists of a gas heated to sufficiently high temperatures that the atoms ionize. The properties of the gas are controlled by electromagnetic forces among constituent ions and electrons, which results in a different type of behavior. Plasma is often considered the fourth state of matter (besides solid, liquid, and gas). Most of the matter in the Universe is in the plasma state. in the boundary region. These data are being combined with IBEX's data, allowing scientists to create a more complete model of the boundary of our Solar System.
To learn more about the Voyager missions, please visit http://voyager.jpl.nasa.gov/.