The European Space Agency's FLEX satellite has advanced on its path to orbit after being fuelled at the European spaceport in French Guiana, ahead of its scheduled launch on 15 September at 03:21 CEST (22:21 local time on 14 September).
Once launched and operational, this new ESA Earth explorer satellite, equipped with a Fluorescence Imaging Spectrometer, will provide new insights into the health of vegetation worldwide by measuring the faint fluorescence glow emitted as plants capture light for photosynthesis. This signal, invisible to the human eye, varies according to environmental conditions and plant health, allowing scientists to detect vegetation stress before it becomes evident on the ground.
FLEX will deliver the first global maps of vegetation fluorescence at a spatial resolution of 300 m × 300 m, providing a new way to assess photosynthetic activity. This data will improve understanding of how carbon moves between plants and the atmosphere, and how photosynthesis drives carbon and water cycles.
Photosynthesis is one of the planet's most important natural processes, underpinning food production and absorbing enormous quantities of carbon dioxide from the atmosphere. However, scientists still have significant gaps in their understanding of how vegetation responds to drought, heat, changes in rainfall and other environmental stresses. FLEX is intended to help close that gap.
The FLEX satellite arrived in French Guiana in mid-July, alongside the Copernicus Sentinel-3C satellite, following a two-week sea voyage from Nice, France. At the European spaceport, engineers have carried out inspections and preparations to ready both satellites for take-off aboard a Vega-C rocket in the early morning of 15 September.
For FLEX, the latest milestone was the hazardous and delicate process of loading the satellite with 30 kg of highly volatile fuel. This propellant will enable FLEX to perform manoeuvres after rocket separation and throughout its planned mission of at least 3.5 years, during which it will observe at least three seasonal vegetation cycles in both hemispheres.
Frank de Bruin, ESA's Launch Campaign Manager for FLEX, said: "The preparations for launching our satellite have gone very well here at the European spaceport and I am grateful to everyone involved. For the fuel loading, everyone except the fuel experts left the clean room for safety reasons. Everything went according to plan and FLEX is now completely fuelled. The next steps involve installing FLEX on its launcher adapter before encapsulating it in the lower position of the Vega-C rocket fairing."
Although FLEX and Sentinel-3C will be launched together, FLEX will initially fly in tandem with the Sentinel-3A satellite. This will provide complementary measurements of clouds, aerosols and water vapour, along with information on the land surface, including surface temperature, land cover type and additional vegetation parameters. Together, these near-simultaneous observations will provide an unprecedented view of the function and condition of vegetation across the planet.
