Rocket Lab announced that its medium-lift Neutron rocket will not make its first launch before 2027 after inspections revealed manufacturing defects in the domes located at both ends of the reusable first stage’s fuel tanks.
The problem consists of air voids between layers of carbon fiber inside the recently manufactured forward dome. These defects could affect the structure’s strength, durability, and reliability, although Peter Beck, Rocket Lab’s founder and chief executive, explained that they do not necessarily mean the dome would fail during flight. He added that the company prefers not to proceed before confirming that appropriate safety margins exist.
The Challenge of Manufacturing a Large Structure
Neutron’s first stage relies on composite structures that provide low weight, high strength, and corrosion resistance, but they are more difficult to manufacture than metal structures, particularly as their size increases. Rocket Lab describes the first stage as the largest compressed composite structure of this type ever made.
Because the rocket’s large components cannot fit inside conventional autoclaves for thermal processing, the company developed out-of-autoclave processing methods and specialized curing cycles for the fuel tank domes. The voids appeared after a design modification intended to strengthen the structure.
That modification followed the rupture of a composite tank during a hydrostatic pressure test in January, an incident attributed to a manufacturing defect at a critical joint. The tank had been manually manufactured by an external contractor while Rocket Lab was preparing an automated fiber-placement machine. The company says the machine is now operational. It also removed some joints from the tank structure and increased the thickness of some sections; these were the thickest areas in which the voids later appeared.
What Changes in Practice?
Rocket Lab said that modifying the manufacturing process resolved the problem and that a rear dome manufactured using the updated procedure passed inspection. However, manufacturing a new forward dome, along with the time required for the investigation and corrective action, pushed the first launch date into next year.
Neutron still faces essential qualification milestones. Final qualification of the first stage has not yet been completed, nor has qualification of the methane-and-liquid-oxygen-fueled Archimedes engine, nine of which will be used to propel the rocket. After that, the launch campaign will begin at the Virginia Eastern Shore, typically including integrated fueling tests, countdown rehearsals, and a static-fire test.
Delay Doubles the Development Schedule
Rocket Lab announced Neutron in 2021, targeting a first flight in 2024, meaning that the development schedule has now extended to roughly twice the original duration. The rocket differs from the smaller Electron in size and capability: Neutron has a diameter of approximately 7 meters, and its targeted low Earth orbit capacity is close to 13,000 kilograms, compared with Electron’s capacity of approximately 300 kilograms.
Neutron’s design relies on opening the first stage’s nose minutes after liftoff to release the upper stage and payload, then closing it and returning to land on an offshore platform for reuse. With this rocket, Rocket Lab is targeting broader launch contracts, including U.S. military organizations and operators of large satellite constellations, in a market that also includes Relativity Space, Stoke Space, and Firefly Aerospace.
Editorial reading: The announcement represents more than a scheduling delay; it reveals that scaling composite-structure technology from the smaller Electron to a compressed first stage with a diameter of 7 meters remains a major manufacturing risk. The rear dome’s successful inspection is a positive indicator, but it does not resolve the questions surrounding qualification of the first stage and engines or the integrated tests. Therefore, 2027 remains an announced target, not a guarantee that service will begin that year.