The Soil Moisture and Ocean Salinity (SMOS) probe took off on top of a Russian Rockot launcher from the Plesetsk cosmodrome in northern Russia, and is now orbiting 760 kilometers (472 miles) above Earth.

By providing the first combined space-based measures of soil moisture and ocean salinity, SMOS will fill important gaps in scientific knowledge about our planet's life-giving water cycle.

It will also help meteorologists predict extreme weather events and make more accurate forecasts in near-real time, say experts.

"Climate change is a fact, but its impact on precipitation, evaporation, surface runoff and flood risks is still uncertain," said Yann Kerr, a research at the Center for the Study of the Biosphere from Space and scientific director for the SMOS mission.

"The availability of water plays a more important role on these impacts than temperature itself," he told journalists.

Scientists rely heavily on computer models to project weather and climate patterns, and having additional data based on concrete observations will make those models more accurate.

SMOS "has long been awaited by climatologists who try to predict the long-term effects of today's climate change," said ESA's Director of Earth Observations Programme Volker Liebig in a communique.

The satellite has two closely intertwined missions.

One is to measure the water content of soil across the planet every three days to a depth of one-to-two metres (six-to-seven feet) which will improve short- and medium-term weather forecasting and monitoring photosynthesis and plant growth.

It is also critical for calculating Earth's carbon cycle, the process by which heat-trapping carbon dioxide is released and absorbed, especially by plants and the oceans.

Climate change, scientists agree, is largely caused by CO2 pollution that has upset that natural balance.

Global estimates of soil moisture will also help forecast drought and flood risk. When a storm breaks, for example, the ability of rainwater to percolate down depends on the type of soil and how much water it is already holding.

Its second job is to measure changes in the salt content of sea surface waters, data that will enhance our understanding of what drives global ocean circulation patterns.

Ocean circulation helps moderate climate, notably by transporting heat from the equator to the poles.

Some studies have suggested that global warming could disrupt these cycles in ways that could dramatically alter regional weather patterns.

Variations in the salinity of ocean waters depend on the addition or removal of fresh water through evaporation and precipitation and, in polar regions, on the freezing and melting of ice.

Both sets of data will be collected by a single instrument called MIRAS, the large Microwave Imaging Radiometer with Aperture Synthesis.

MIRAS connects 69 receivers mounted on three deployable arms to measure the temperature of the reflection of the Earth's surface in the microwave frequency range.

The nominal life of the SMOS mission is three years, with a possible two-year extension.

A second ESA satellite lifted into space Monday, Proba-2, is designed to demonstrate innovative in-orbit technologies.

It will test a new type of lithium-ion battery, an advanced data and power management system, a dual-frequency GPS receiver, an experimental solar panel, an exploration micro-camera and a dozen other technologies.

Proba-2 will also conduct experiments related to solar observation and space weather.