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Guiana - Space

French satellite to test principle of Theory of Relativity

An artist's impression of the Sentinel-1B satellite which will be launched from French Guiana on Friday.
An artist's impression of the Sentinel-1B satellite which will be launched from French Guiana on Friday. ESA

Two satellites, including one by the French national centre for space studies, CNES, will be launched aboard a Soyuz rocket from French Guiana on Friday that will help in monitoring our planet’s environment and test one of the principles of Albert Einstein’s General Theory of Relativity.


The Russian Soyuz rocket will deploy the Sentinel-1B satellite at an altitude of 686 km and along with Sentinel-1A, which was launched in April 2014, it will scan Earth day and night, regardless of the weather.

The mission of the twin Sentinel satellites is to monitor sea ice, oil spills, marine winds, waves & currents, land deformation among and to respond to emergencies such as floods and earthquakes.

This mission is part of European Union’s ambitious Copernicus programme for environmental monitoring. It includes several types of Sentinel satellites which are to operate in pairs.

One of the other probes to be deployed is the French microsatellite Microscope whose mission is to find a breach in one of the principles of the general relativity theory developed by Albert Einstein a century ago.

Microscope, which stands for Micro Satellite drag Compensated for Observation of the Equivalence Principle, is responsible for testing the universality of free fall in vacuum and space, with a precision that is 100 times greater than on Earth.

The satellite will verify 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 perfectly as possible.

On Earth, the principle of equivalence has been verified with a degree of accuracy to the order of the 13th decimal place. Microscope intends to go two decimal places further.

According to a release on the CNES website, “this principle is being pushed to its limits by new theories seeking to reconcile gravitation with fundamental nuclear and electromagnetic interactions, which predict that it could be violated at very weak levels.”

The 130 million euro satellite will be placed in orbit at an altitude of about 711 km.

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