The European Space Agency (ESA) says its FLEX Earth Explorer satellite and the Copernicus Sentinel-3C satellite were launched together aboard a Vega-C rocket from Europe's Spaceport in French Guiana. Flight VV30 lifted off on 15 September at 03:21, which was 14 September at 22:21 local time, according to the agency.

FLEX carries a Fluorescence Imaging Spectrometer intended to detect the faint fluorescence plants emit as they photosynthesise. Because that signal varies with plant health and environmental conditions, ESA says the measurements should give scientists new information on photosynthetic activity and vegetation stress worldwide. Sentinel-3C, the third satellite in the Sentinel-3 series, will continue systematically measuring Earth's oceans, land, ice and atmosphere and supply near-real-time data for ocean and weather forecasting.

ESA describes the flight as Vega-C's first dual launch. Sentinel-3C sat on top of a secondary payload adapter, Vespa, inside the main fairing; after its deployment, the adapter opened to release FLEX. ESA says Vega-C can carry 2300 kg to space, stands 35 m tall and weighs 210 tonnes on the launch pad.