Soyuz-Fregat rocket launch from Baikonur Cosmodrome, Kazakhstan, on 16 July 2000. This was flight ST09 by the French-Russian consortium Starsem. It delivered the first pair of Cluster II satellites into Earth orbit. The satellites are contained in the Fregat upper stage, which sits above three lower stages that successively boost the cargo into orbit. Another pair of Cluster II satellites were launched in August 2000. The four satellites then began a study of the interaction between the solar wind and the Earth's magnetic field.