MOSCOW - Russia's space agency says it has successfully launched three European Space Agency's satellites intended to study Earth's magnetic field.

Roscosmos said that a Rokot booster rocket launched Friday from the Plesetsk launchpad in northwestern Russia put the three Swarm satellites into their designated orbits.

During their four-year mission, the satellites will help gather data that would help better understand the workings of Earth's magnetic field that protects its biosphere from deadly space radiation, ESA said. The satellites will monitor the magnetic field from Earth's core to its upper atmosphere and perform precise measurements to evaluate the current weakening of the magnetic shield.

The satellites are controlled by ESA teams at the European Space Operation Center in Darmstadt, Germany.