A European Vega-C rocket lifted off before dawn Tuesday from the Spaceport in Kourou, French Guiana, carrying two Earth-observation satellites in the launcher's first flight to release payloads from two separate deployment points on a single mission. Liftoff came at 03:21 CEST (22:21 local time Monday), and controllers at the European Space Agency's operations center in Darmstadt, Germany, confirmed signals from both spacecraft within roughly an hour.
The heavier of the pair, the 1,143-kilogram Sentinel-3C, separated first. It is the third satellite in the Copernicus program's Sentinel-3 series and carries instruments to measure sea-surface height, ocean and land temperature, and ocean and land color, along with sensors that track aerosols, clouds and wildfire activity. It is built to eventually take over from the aging Sentinel-3A. FLEX, ESA's 397-kilogram Earth Explorer mission, deployed about an hour later. It is the agency's first satellite designed specifically to detect photosynthesis from orbit, using a Fluorescence Imaging Spectrometer tuned to the 500-to-780-nanometer band to pick up the faint glow plants emit while converting sunlight into energy.
Reading a faint signal
That fluorescence is far dimmer than reflected sunlight, which is why FLEX will fly in loose formation with a Sentinel-3 satellite, initially Sentinel-3A, later Sentinel-3C, orbiting roughly a kilometer apart on a 27-day repeat cycle so the two can cross-calibrate their measurements of the same patch of ground within minutes of each other. Scientists say the combined data should reveal how efficiently vegetation is turning carbon dioxide and light into growth, an indicator of plant stress that shows up before visible wilting or color change and that could sharpen estimates of how much carbon land ecosystems are absorbing as the climate warms.
"Today's launch is the culmination of years of scientific innovation, engineering excellence and international cooperation," ESA Earth observation director Simonetta Cheli said in a statement. Sentinel-3C is jointly managed with Eumetsat once commissioned, part of the EU-funded Copernicus network that already underpins weather forecasts, flood and wildfire monitoring, and climate reporting across Europe.
The mission also marks a further step back for Vega-C after a rocky stretch: the vehicle was grounded for nearly two years following a December 2022 launch failure that destroyed two Airbus satellites, and a subsequent engine test failure in 2023 pushed its return to flight to December 2024. Tuesday's flight, designated VV30, was the rocket's eighth overall and second of 2026, flown by manufacturer Avio under a European Space Agency contract. Avio chief executive Giulio Ranzo said the launch helped confirm Avio as a reliable launch service operator.
Both satellites have now entered a commissioning phase known as launch and early orbit, during which ground teams check subsystems before science operations begin. Sentinel-3C is designed to operate into the 2030s; FLEX carries a planned mission of three and a half years. Early calibrated data from both instruments is expected within several months, according to ESA.
