Rumba

Second of the two 2000 Soyuz-Fregat launches that completed ESA's Cluster II constellation, carrying Rumba and Tango to join Salsa and Samba from three weeks earlier. The four identical probes flew in a tetrahedral formation to measure Earth's magnetosphere in three dimensions, a rebuild of the original Cluster satellites lost on the maiden Ariane 5 in 1996.