A European satellite is set to provide major new insights into how water is cycled around the Earth.

The Smos spacecraft will make the first global maps of the amount of moisture held in soils and of the quantity of salts dissolved in the oceans.

The data will have wide uses but should improve weather forecasts and warnings of extreme events, such as floods.

A Rokot launcher carrying Smos lifted off from the Plesetsk Cosmodrome in Russia at 0450 (0150 GMT) on Monday.

Some 70 minutes later, the upper-stage of the Rockot released the spacecraft, and telemetry confirming all was well with the mission was acquired by the Hartebeesthoek ground station, near Johannesburg, South Africa.

The Soil Moisture and Ocean Salinity (Smos) satellite is part of an armada of European spacecraft being sent into orbit over the next few years to study the planet.

"We had a very beautiful launch," said Jean-Jacques Dordain, the director-general of the European Space Agency (Esa).

"This is not just a satellite; this is a very important event. This is the second of our Earth Explorers and with that we confirm that Esa is the space agency of the world making the best efforts for Earth science and a new understanding of climate change."

Smos carries a single instrument - an interferometric radiometer called Miras. Some eight metres across, it has the look of helicopter rotor blades.