Following their final preparations at Thales Alenia Space in Cannes, France, two new ESA-developed satellites have set sail from Nice for French Guiana, where they will undergo final checks and readied for their joint launch aboard a Vega-C rocket this September.

One of the satellites is FLEX – ESA’s Earth Explorer photosynthesis mission. Equipped with the Fluorescence Imaging Spectrometer, FLEX will reveal new insights into plant health by detecting the faint fluorescence they emit as they absorb sunlight during photosynthesis. Although invisible to the human eye, this subtle glow varies with plant health and environmental conditions, enabling scientists to assess photosynthetic activity, vegetation health and detect signs of stress on a global scale.

The other satellite aboard is Copernicus Sentinel-3C – the third satellite in the Sentinel-3 series. Like the two Sentinel-3 satellites already in orbit, Sentinel-3C carries a suite of cutting-edge instruments that measure the height of the ocean, sea and ice surface temperatures, ocean colour and sea ice thickness. Over land, it measures vegetation, wildfires, the variations of ice sheet as well as the water height of inland lakes and rivers. Its data support the Copernicus Services and help understand Earth dynamics.

The ship, with this precious cargo, will spend the next two weeks crossing the Mediterranean Sea and then the Atlantic Ocean before docking at Pariacabo, the port of Kourou, on 13 July. Once the two satellite containers have been transported to Europe’s Spaceport, the satellites will be put through an intensive eight-week launch campaign in preparation for liftoff.