ESA launches satellites to track plant health, oceans

A rocket lifted off from French Guiana before dawn Tuesday, carrying two European satellites. One, called FLEX, is the first ever built to measure the dim glow plants give off during photosynthesis. That glow reveals how stressed or healthy a plant is, often before it turns visibly brown. The second satellite, Sentinel-3C, keeps watch on oceans, ice, and wildfires.

FLEX is a genuinely new kind of instrument, not just an upgraded camera. Farmers and scientists currently rely on satellites that photograph how green a crop looks. Green can lag behind real trouble by weeks. FLEX instead reads a signal tied directly to photosynthesis itself, catching stress much earlier. The launch also marked a first for the Vega-C rocket. It flew two separate satellites on one dispenser for the first time. Both spacecraft now begin weeks of in-orbit testing before their data goes to work.

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Will FLEX's early-warning data actually reach farmers and drought planners in time to matter? That depends on how fast the space agency can turn raw signals into usable maps. The technology works. Getting it into the hands of people who need it is the harder part.