NetherlandsThe new Ariane 6 aft bay is 400 kilograms lighter.

That is half the 800 kilograms the Netherlands Space Office reported in July 2024.

The aft bay holds the Vulcain 2.1 engine and passes its thrust to the stage, and weighs about 5 tonnes.

Airbus Netherlands president Rob Postma did not explain the gap, though a 2025 report cited more than 550 kilograms.

Flight Model 16 is due to fly on an Ariane 6 mission in 2027.

How each outlet framed it
European Spaceflight
reports Airbus's Postma LinkedIn post and the 400 kg saving, half the 800 kg promised in 2024

Sources: European Spaceflight