Rocket Lab completes full-duration hot fire of Neutron's AVac engine

Rocket Lab said it completed a full-duration hot fire of the Archimedes Vacuum (AVac) engine that will power Neutron's second stage, a critical propulsion milestone toward the medium-lift rocket's first flight. The test clears a major item on the path to Neutron's debut, which the company continues to target for the fourth quarter of 2026 after tank-rupture and other setbacks pushed the schedule back from an earlier 2026 goal. Rocket Lab's smaller Electron rocket has meanwhile posted a record first half of 2026, driving a rise in launch contracts and revenue.