 The cluster mission was launched in 2000 and consisted of four satellites orbiting the Earth. The cluster ion spectrometry, CIS, instrument was used to measure the ion distribution in the magnetosphere from thermal energies up to 40 keV slash E. This instrument had two different sensitivities, allowing it to have a higher dynamic range than other similar instruments. It was able to obtain good data in the central plasma sheet, magnetopause crossings, magnetosheath, solar wind, and cusp measurements. Additionally, observations in the auroral regions were possible at radial distances of four to six Earth radii. These results demonstrate the importance of multi-spacecraft measurements using identical instruments, as well as opening a new area of study in magnetospheric and solar wind magnetosphere interaction physics. This article was authored by H. Reem, C. Euston, J. M. Boscade, and others.