Summary
ESA says FLEX and Copernicus Sentinel-3C are scheduled to launch together on a Vega-C rocket on 15 September 2026. FLEX will measure faint plant fluorescence alongside data from a Sentinel-3 satellite to help characterise global vegetation.
ESA says its FLEX and Copernicus Sentinel-3C satellites are scheduled to launch together aboard a Vega-C rocket on 15 September 2026. The launch is planned for 03:21 CEST from Europe’s Spaceport in French Guiana, or 22:21 local time on 14 September.
The mission pairing is intended to combine measurements of plant activity with observations of the conditions around it. ESA outlined the launch schedule and the satellites’ roles in a media briefing held on 4 September.
FLEX will measure a faint signal from plants
FLEX carries a Fluorescence Imaging Spectrometer designed to detect the faint fluorescence plants emit as they absorb sunlight during photosynthesis. The glow is invisible to the human eye, and ESA says its variation can provide information about plant health and environmental conditions.
FLEX is intended to orbit in tandem with a Sentinel-3 satellite. That satellite will supply observations of clouds, aerosols and water vapour, as well as land-surface information including surface temperature, land-cover type and other vegetation parameters. Collecting these measurements near the same time is intended to give researchers a more complete view of vegetation function and status across the globe.
The combined approach matters because a signal associated with plant activity can be interpreted alongside observations of the surrounding atmosphere and land surface. ESA describes the resulting data package as a way to monitor global vegetation function and status; the briefing presents this as a planned capability of the mission.
Sentinel-3C’s wider Earth-observation role
Sentinel-3C is the third satellite in the Copernicus Sentinel-3 series. Like the two earlier satellites in orbit, it carries instruments for systematic measurements of Earth’s oceans, land, ice and atmosphere. ESA says the series provides information for monitoring large-scale global dynamics and supplies near-real-time data for ocean and weather forecasting.
Vega-C, the launch vehicle, is an evolution of Europe’s Vega rocket family. ESA says it offers greater performance and payload capacity than its predecessor and can launch up to 3,300 kg into space. The 15 September flight is scheduled to carry both satellites from French Guiana.