Vega-C flight VV30 with FLEX and Sentinel-3C
Image: ESA
Machine-written summary, checked against the sources below
ESA's FLEX and Copernicus Sentinel-3C satellites are set to launch together on a Vega-C rocket, flight VV30, from Europe's Spaceport in French Guiana on 15 September at 03:21 CEST. Sentinel-3C extends the Sentinel-3 constellation providing optical, radar and altimetry data for marine and land services, while FLEX will map vegetation fluorescence to quantify photosynthetic activity.
From the ESA Blogs.
Summary by ESA, the primary source