PARIS, 16 Dec 2004 (AFP) - The CNES Parasol micro-satellite, to be launched on Saturday by an Ariane 5 with six other passengers, should provide a better understanding of the impact on the climate of clouds and aerosols, these fine particles suspended in the air.
For a long time, only greenhouse gases have been taken into account to study the phenomenon of global warming, says the National Center for Space Studies. But aside from the warming greenhouse effect, aerosols and clouds, by shielding the sun as a sunshade, tend to cool the Earth-Atmosphere system.
Modeling work has shown that natural aerosols (volcanic ash or sea spray), or those created by human activity, play a crucial role in climate change and even constitute, according to the Academy of Sciences, "the greater source of uncertainty "in the climate study.
The whole question is to determine what is for the planet, globally but also according to the regions, the final balance of the competition which is played between this parasol effect and the greenhouse effect.
Parasol (Polarization and Reflectance Anisotropy at the top of the Atmosphere, coupled with an observation satellite carrying a Lidar) should provide some answers. As the second satellite in the Myriade sector developed by CNES, it will measure polarized light in several directions, in order to better characterize clouds and aerosols, other than by their spectral signature observed more conventionally.
To this end, the micro-satellite will include a Polder wide-field imaging radiometer, designed thanks to the contribution of the Atmospheric Optics Laboratory of Lille (CNRS-USTL).
The information provided will be used to specify the quantity and size distribution of aerosols over the ocean and their turbidity index (suspended solids content) over land. They will also contribute to the detection of clouds, the determination of their thermodynamic phase, their altitude and the estimation of the flux reflected in the solar domain. The water vapor content will also be estimated.
Parasol, whose expected life span is two years, was produced under the supervision of CNES. Its development relied heavily on the Polder payload program and Demeter, CNES's first microsatellite, for the platform, in order to reduce costs and lead times.
The scientific responsibility for the mission lies with the Atmospheric Optics Laboratory of CNRS (LOA, Lille).
Parasol will be positioned relative to the Aqua and Aura satellites (Nasa), Calipso (NASA / Cnes), Cloudsat (NASA / Canadian Space Agency) to complete the training called "A-Train", an exceptional space observatory to be completed in 2008 by another NASA satellite, Oco.