FLEX and Sentinel-3C launched

A Vega-C rocket lifted off from Europe’s Spaceport in French Guiana on 15 September, carrying the European Space Agency’s FLEX Earth Explorer satellite and the Copernicus Sentinel-3C satellite into orbit. The dual launch used a Vespa adapter to stack both spacecraft inside the rocket’s fairing, with Sentinel-3C deployed first, followed by FLEX about an hour later. Ground teams at ESA’s European Space Operations Centre in Germany confirmed signal acquisition from both satellites, validating their safe separation and initial contact. Mission controllers are now conducting a detailed checkout of systems during the launch and early orbit phase to ensure readiness for operations.

FLEX, developed under ESA’s FutureEO programme, is the agency’s first satellite dedicated to measuring photosynthetic activity from space. Its Fluorescence Imaging Spectrometer detects faint fluorescence emitted by plants during photosynthesis, providing direct insights into vegetation health and ecosystem productivity. The mission aims to assess how efficiently plants convert sunlight and carbon dioxide into energy, supporting studies on environmental stress and climate change impacts. Sentinel-3C, the third satellite in its series, continues long-term environmental monitoring by systematically observing oceans, land, ice, and atmosphere.

Sentinel-3C carries instruments to measure ocean and land-surface temperatures, ocean colour, sea and ice conditions, vegetation, and inland-water levels. The satellite will deliver near-real-time data to support ocean forecasting, climate monitoring, environmental management, and scientific research as part of the EU’s Copernicus programme. ESA developed the satellite, while Eumetsat will handle routine operations and deliver marine and near-real-time atmospheric data after commissioning. ESA and Eumetsat will jointly provide mission data and services to global users.

The launch on Vega-C flight VV30 demonstrated the rocket’s capability to place two Earth observation missions into distinct orbits. Vega-C, an evolution of Europe’s Vega family, can launch up to 2300 kg into low-Earth orbit and uses three solid-propellant stages before a liquid-propellant stage for precise satellite placement. ESA leads the Vega-C programme with Avio as prime contractor and launch service operator. Following deployment, FLEX will initially orbit alongside Sentinel-3A, with Sentinel-3C later replacing Sentinel-3A to form a tandem formation, enabling combined measurements of vegetation fluorescence and complementary environmental data.