Rocket Lab Delays Neutron Launch Into 2027 After Tank Defect

Rocket Lab has postponed Neutron’s inaugural launch into 2027 after inspections found small voids inside a carbon-fiber component of the rocket’s first-stage propellant tank. The company’s October 14 program update confirmed the revised year but did not provide a replacement launch date.

The defects appeared between layers of carbon fiber in the first stage’s forward tank dome, one of the large curved structures that closes the propellant tank. These air pockets can reduce structural strength and reliability, making them unacceptable in hardware that must withstand demanding pressure, temperature and flight loads. Rocket Lab chose to replace the dome rather than proceed with a component that might not meet its required margins.

“Possible success isn’t our standard,” CEO Peter Beck said in explaining that decision.

The finding is consequential because Neutron is Rocket Lab’s route into the medium-lift launch market, where it plans to compete for larger commercial satellite deployments and government missions. Its debut had been expected in late 2026. A comparatively small internal manufacturing defect has now moved the entire vehicle’s first flight into another calendar year.

The manufacturing process had already changed

The forward-dome problem emerged after Rocket Lab shifted to automated fiber placement, a robotic process that lays carbon fiber into the required shape. That transition followed an earlier qualification failure involving a manually produced first-stage tank.

Automation is intended to improve production speed and consistency, particularly for structures as large as Neutron’s. Rocket Lab previously said its custom 90-ton automated fiber-placement machine would produce the vehicle’s large composite structures and could save more than 150,000 manufacturing hours. The machine also incorporates real-time inspection intended to identify small defects as successive layers are deposited.

Those capabilities do not remove the need to qualify the complete manufacturing process. Fiber placement is only part of producing a finished composite structure; the laid material must also proceed through curing and inspection. Neutron’s dome shows why a repeatable robotic layup still has to produce acceptable material after the full fabrication cycle.

Engineers reproduced the void problem and modified the automated process. A separate aft dome subsequently produced improved results under the revised method, according to Beck. That is an important recovery step because it indicates the defect can be recreated and addressed rather than remaining intermittent and poorly understood.

It is not yet the final qualification result. Rocket Lab must manufacture a replacement forward dome, cure it and verify through inspection that the revised process produced acceptable hardware. The company expects to complete manufacturing and inspection of that component before the first quarter of 2027.

Tank tests now control the path to launch

Once accepted, the replacement dome must be incorporated into the full first stage. Rocket Lab expects first-stage assembly, hydrostatic testing and cryogenic testing during the first quarter of 2027.

Hydrostatic testing uses liquid pressure to check a structure’s integrity, while cryogenic testing evaluates it under the extremely low temperatures associated with Neutron’s liquid oxygen and liquid methane propellants. For a composite tank, those tests are essential because pressure and deep cooling impose conditions that cannot be settled by visual inspection alone.

The schedule therefore depends on a chain of manufacturing and qualification milestones rather than merely selecting another launch day. The replacement forward dome must pass inspection, the first stage must be assembled, and the integrated tank structure must complete its pressure and cryogenic test program. Rocket Lab plans to announce a new target launch date only after that work advances.

Neutron’s delay also narrows the margin for another manufacturing setback. Development spending continues while the vehicle remains unavailable to customers, and every qualification problem pushes commercial and government missions farther out. Rocket Lab says demand remains and has indicated that additional customer contracts are coming, but the rocket must first convert its revised composite process into a completed, tested stage.

The next decisive result will not occur at the launch pad. It will come when the replacement dome clears inspection and the assembled first stage survives its first-quarter 2027 structural test campaign.

By David Whitaker — Associate editor for AMI’s aerospace and drone systems desk, translating flight systems, aircraft programs, spaceflight, and UAV developments into accessible technical stories.