Satellites to monitor the Earth and defy Einstein – Ouest-France

One will monitor the Earth with radar, the other intends to challenge a principle of Einstein’s theory, two satellites will be launched tomorrow, Friday, by a Russian Soyuz rocket from French Guiana (see inset) <. p> Sentinels 1-a and 1-B, duet shock to monitor the Earth the Sentinel-1 European mission consists of a pair of satellites (1-a and 1-B) each equipped with sophisticated radar and capable of providing images of the surface of the Earth day and night, whatever the weather. Thus, Soyuz will be responsible for tomorrow to orbit European satellite Sentinel-1B, twin brother of Sentinel-1A launched it two years ago.

In orbit above the land and ocean, Sentinel- 1A continue to provide images to map ice or detect possible oil spills, to observe land use and monitor landslides. Once placed on the target orbit at an altitude of about 686 km, Sentinel-1B scrutinize him, each area of ​​the Earth every six days.

Microscope , alone with Einstein once the duo formed shock, Soyuz will also be responsible to ship the French Microscope (microsatellite drag Compensated for Observation of the Equivalence Principle). A microsatellite 300 kg which, orbiting at an altitude of about 711 km, hopes to find a breach in the general relativity theory developed by Albert Einstein a century ago.

How? By testing in vacuum and space universality of free fall, with a precision 100 times greater than on Earth. But also by checking the principle of “equivalence” between gravity and acceleration on which Albert Einstein built his theory. It will study the relative motion of two bodies in performing a free fall as perfect as possible.

“U n very important moment in the evolution of the physical “ if, on Earth, the principle of equivalence has been verified with a relative degree of accuracy in the order of the 13th decimal, the high-precision microscope hears him up to the 15th decimal place [ie the mass ratio of a tiny fly on a supertanker 500 000 tonnes, Ed].

“If Microscope is a violation of the equivalence principle, this will be a very important moment in the evolution of the physical , said the french physicist Thibault Damour. We will then know that the theory of Einstein’s relativity is not a complete description of gravitation, there are new forces that contribute to it. “

The launch of the Soyuz launcher from the Guiana Space Centre (CSG) is provided at 18 h 02 time in Kourou (21 h 02 GMT ). Its new mission, carried out on behalf of the European Union and the European Space Agency (ESA), is part of the ambitious European program Copernicus, for monitoring the environment.