Watch: FLEX and Sentinel-3C launch on Vega-C

ESA’s FLEX satellite and Copernicus Sentinel-3C are scheduled to launch together aboard a Vega-C rocket on 15 September at 03:21 CEST (14 September at 22:21 local time). The VV30 launch will take place from Europe’s Spaceport in French Guiana, and live coverage starts at 02:50 CEST on ESA YouTube or ESA Web TV Two.

The broadcast schedule lists: 02:50 broadcast begins; 03:21 liftoff; 03:51 break; 04:12 broadcast resumes; 04:21 Sentinel-3C separates; 04:32 break; 05:07 broadcast resumes; 05:17 FLEX separates; 05:36 broadcast ends.

FLEX—the Fluorescence Explorer—is ESA’s next Earth Explorer mission. It is designed to reveal a phenomenon invisible to the human eye: the faint fluorescence emitted by plants as they photosynthesise. Its Fluorescence Imaging Spectrometer will detect and measure this very weak signal from orbit. Because the fluorescence varies with plant health and environmental conditions, the measurements will provide new information about photosynthetic activity and vegetation stress on a global scale. FLEX will produce global maps of vegetation fluorescence at 300 × 300 metre resolution, offering a new way to study how plants interact with the atmosphere and how carbon and water move through Earth’s ecosystems.

Copernicus Sentinel-3C is the third satellite in the Sentinel-3 series. Like its two predecessors already in orbit, it carries a suite of advanced instruments that systematically measure Earth’s oceans, land, ice and atmosphere. These observations support monitoring and understanding of large-scale processes and dynamics across the planet, while providing essential near-real-time information for ocean and weather forecasting. Sentinel-3 mission data support the Copernicus Services and help understand Earth dynamics.

The two satellites are being launched together. Sentinel-3C will be injected into orbit first so that it sits above FLEX in the Vega-C fairing. To accommodate both, FLEX is encapsulated within the lower part of a secondary payload adapter called Vespa, and Sentinel-3C was then mated to the upper part of Vespa. FLEX will ultimately orbit in tandem with one of the Copernicus Sentinel-3 satellites—though not Sentinel-3C initially. Sentinel-3 will be used to provide critical information on the atmosphere, such as clouds, aerosols and water vapour, as well as information about the land surface. The dual launch is presented as the next step in Europe’s commitment to observe and understand our changing planet.