FLEX and Sentinel-3C ready for liftoff on Vega-C

Two Earth observation satellites — ESA's Fluorescence Explorer (FLEX) and the third satellite of the Copernicus Sentinel-3 mission — have been encapsulated inside the nose cone of a Vega-C launcher and are awaiting liftoff at Europe's Spaceport in French Guiana. Launch is scheduled for tonight: 15 September at 03:21 CEST (14 September at 22:21 local time). The two separate missions will capture data about our changing global environment: FLEX will monitor the health of Earth's vegetation, while Sentinel-3C joins the two Sentinel-3 satellites already in orbit to monitor oceans, land, ice and atmosphere for Copernicus, the Earth observation component of the European Union's Space Programme. The Vega-C rocket will first deploy Sentinel-3C and then, after some launcher manoeuvres, FLEX, which is fitted inside the Vespa+ payload adapter.

FLEX is an Earth Explorer mission — part of ESA's fleet of small scientific satellites designed to explore different aspects of Earth's environment, from the magnetosphere to ice caps, and from biomass to the atmosphere. It is dedicated to gathering data on the health of vegetation on a global scale by detecting the faint glow emitted by plants as they photosynthesise. Although invisible to the human eye, this fluorescence can be detected from space and indicates whether plants are healthy or stressed by environmental conditions. The satellite's Fluorescence Imaging Spectrometer can detect and measure this incredibly weak signal from an altitude of 814 km. The mission is expected to produce global maps of vegetation fluorescence at a resolution of 300 m × 300 m, offering a new way to study how plants interact with the atmosphere and how carbon and water move through Earth's ecosystems.

Since the first Sentinel-3 satellite launched a decade ago, the mission's data on oceans, land, ice and atmosphere have provided robust datasets for operational applications and scientific research, improving understanding of climate change and underpinning global climate policies. The launch of the mission's third satellite heralds the continuity of this vital source of knowledge. Sentinel-3C carries four science instruments that capture data quickly across entire regions. During the routine operations phase, Sentinel-3 is managed jointly by Eumetsat and ESA on behalf of the European Commission.

The Vega-C programme is led by ESA, working with Avio as prime contractor and design authority, and ensures Europe has versatile and independent access to space. Vega-C stands 35 m tall, is credited in the announcement with a 2300 figure for its lift capability, and complements the Ariane family of launchers.