The Global Positioning System (GPS) has been operational since 1995. The main link in the system is a constellation of 31 satellites positioned on six orbital planes such that any point on the Earth’s surface is covered at all times by at least 6 satellites. These satellites emit on two frequencies a time signal generated by the atomic clocks on board. Satellites also emit their ephemeris (position and speed at the time of emission as well as prediction of positions and speeds for the following hours). The measurement principle is close to triangulation. Knowing the time of transmission and the reception time of the signals by a receiver and postulating a model of speed of the electromagnetic waves between the satellites and the receiver, it is possible to calculate the position of the receiver on the terrestrial surface. This system allows position measurements with an accuracy of a few meters for acquisitions lasting one second.
Very high resolution airborne imagery (THR) is complementary to satellite imagery. It allows to “zoom” on mega pixels an area of limited scientific interest (ROI) or the satellite only sees it under a few pixels. It is thus possible to obtain centimetric resolutions and be able to estimate from one mission to another the changes of terrain and the quantities of displaced materials with more and more realistic specifications.
The laboratory has the classical tools for preparation and analysis of rock samples:
– sawing and grinding equipment;
– workshop for making thin blades
– microscopes and associated image acquisition system Electronic microprobe
For the analysis of the constituent elements of the rocks, we have access to the electron microprobe, known as “Microsonde Ouest”, jointly acquired between Ifremer, the Universities of Brest, Rennes and Nantes, and the UNSA of Rennes. This microprobe is installed on the Ifremer site.
The LGO litholamellage and milling plant includes sawing and grinding rock equipment as well as equipment for manufacturing thin sections and polished sections.
The laboratory is equipped with several polarizing microscopes for the observation of thin sections in transmitted or reflected light, as well as several binocular microscopes for the observation and sorting of minerals or fossils. A high definition digital camera allows the acquisition of high quality images.