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Europe launches satellite to monitor climate change
World’s first mission to study the global water cycle from Space
photo credit: ESA-AOES Medialab
The Soil Moisture and Ocean Salinity (SMOS) mission will make global observations of soil moisture over Earth’s landmasses and salinity over the oceans. Variations in soil moisture and ocean salinity are a consequence of the continuous exchange of water between the oceans, the atmosphere and the land – Earth’s water cycle.

The world’s first satellite designed to map the saltiness of the sea and monitor water content in soil across the planet was launched on 2 November 2009 by the European Space Agency (ESA). The Soil Moisture and Ocean Salinity (SMOS) mission will survey these key indicators of the water cycle between oceans, air and land. They have never before been measured globally from Space, and SMOS will play an important role in monitoring climate change — and in predicting severe weather events.

SMOS was carried aboard a Rockot launch vehicle from Eurockot GmbH, which lifted off from the Plesetsk Cosmodrome, about 200 km south of Archangel in the north of the Russian Federation. The satellite is now in a sun-synchronous orbit some 760 km above Earth, controlled on behalf of ESA by the Centre National d’Etudes Spatiales (CNES) in Toulouse, France. After its equipment has been checked and calibrated, SMOS is expected to become fully operational within six months.

It will measure the natural microwave emissions from the Earth’s surface, which alter with moisture levels on land or the salinity of the sea. When meteorologists know how wet the soil is, they can more easily predict floods, droughts and water reserves, as well as weather generally. Salty water will sink below less dense fresh water, so studying the salinity of the oceans provides information about currents that circulate the globe, exchanging heat and fundamentally affecting the climate. This information on a global scale, now to be provided by SMOS, “has long been awaited by climatologists who try to predict the long-term effects of today’s climate change,” commented Volker Liebig, ESA’s Director of Earth Observation Programmes, at the satellite’s launch.

Normally, detecting microwave radiation in a timely and global manner would require an antenna that is too large to be launched on a rocket. Instead, SMOS is equipped with a Microwave Imaging Radiometer with Aperture Synthesis, or MIRAS. It connects an array of 69 small receivers mounted on three arms that extend from the satellite. Together, they can capture a 1000-km field of view to provide a complete map of the Earth every three days — including remote areas that have not been easily monitored by ground observations. Images will be synthesized to a scale of 50 km for soil moisture or 200 km for ocean salinity.

photo credit: ESA, 2009
This Envisat image captures an enormous plankton bloom stretching across the Barents Sea off northern Europe. Envisat acquired this image on 19 August 2009 with its Medium Resolution Imaging Spectrometer (MERIS) instrument. MERIS’s primary objective is to provide quantitative ocean-colour measurements, but the sensor can also serve applications in atmospheric and land-surface science.

The innovative MIRAS device was created by Astrium Spain, formed by EADS CASA Espacio and Astrium CRISA (Computadoras, Redes e Ingeniería SA). The Astrium group of companies is a wholly owned subsidiary of the European Aeronautic Defence and Space Company (EADS). The satellite carrying MIRAS was developed by ESA in cooperation with France’s CNES and Spain’s Centro para el Desarrollo Tecnológico Industrial (CDTI). It is based on the Proteus small satellite platform, designed and built by Thales Alenia Space, of France.

SMOS is the second element of the Earth Explorer programme that ESA is conducting to gather new environmental data. It follows the Gravity and steady-state Ocean Circulation Explorer (GOCE) satellite, launched in March 2009, and further missions are being prepared. Cryosat-2, which will measure the thickness of ice sheets on land and sea, is due for launch in February 2010. It is scheduled to be followed in 2011 by ADM-Aeolus, to study atmospheric dynamics, and the Swarm mission to monitor the weakening of the Earth’s magnetic field. Due for launch in 2013 is the EarthCARE mission to study clouds and aerosols.

The rocket that launched SMOS also carried into orbit another ESA satellite: Proba-2. Like its predecessor Proba-1, it is designed to demonstrate a range of technologies for future satellite systems and equipment to carry out Space science. In addition, Proba-2 carries two Belgian solar physics instruments and two Czech plasma physics experiments. The joint launch of the two satellites “will provide Europe with new tools to better understand our planet and climate change, as well as new technology breakthroughs,” said ESA’s Director General Jean-Jacques Dordain.


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