The first two Cluster satellites have reached their operational orbits, five days after their launch last month from the Baikonur Cosmodrome, Kazakhstan, on a Starsem Soyuz-Fregat booster.
The two Cluster satellites, built by Astrium for the European Space Agency and named Salsa and Samba, reached their 16,870 x 121,100km (10,480 x 75,200 miles) orbits after five on-board engine burns in four days, including a "dog-leg" manoeuvre to alter orbital inclination.
Two more Cluster satellites - Rumba and Tango - will be launched on another Starsem Soyuz-Fregat booster on 9 August to complete the constellation.
The 1,200kg (2,640lb) Astrium-built satellites, carrying 11 science instruments weighing 71kg provided by Austria, France, Germany, Sweden, the UK and the USA, will study the solar wind and how it interacts with the Earth's magnetosphere.
The satellites will fly in a tetrahedral formation collecting data on solar-Earth interaction.
Source: Flight International