Rocket Lab Neutron and Firefly’s Eclipse Face Delays and Development Challenges

Rocket Lab’s Neutron and Firefly and Northrop Grumman’s Eclipse are among the next-generation medium-lift rockets being developed to follow Antares. However, both programs face technical and schedule uncertainty as their companies work through engine development and large carbon-composite structures.

Rocket Lab Neutron: Carbon-Composite Challenges Could Delay First Launch

For a long time, it seemed that Neutron would be the next new medium-lift rocket to debut after Antares. However, the program has encountered several challenges. Rocket Lab has experienced issues with its Archimedes engine, and the company recently revealed additional difficulties involving Neutron’s carbon-fiber dome.

Rocket Lab Director Peter Beck said this month that Neutron’s first stage is “the largest pressurized structure ever made of carbon composite materials.” He added that, because of its scale, Rocket Lab had to develop a new out-of-the-autoclave manufacturing process, including custom curing cycles for very large parts such as the forward and aft domes of the Stage 1 propellant tank.

Building structures of this size is not straightforward. With little flight hardware publicly visible, it remains unclear whether Rocket Lab can meet its latest target of launching Neutron sometime in 2027.

Expected launch debut: January 2028

Firefly and Northrop Grumman’s Eclipse Rocket

The Antares rocket was originally developed by Orbital Sciences, a company later acquired by Northrop Grumman. A few years ago, Northrop Grumman, seeking a domestic alternative to Antares, announced a partnership with Firefly to co-develop the Eclipse rocket.

Firefly is developing the Miranda engine that will power Eclipse’s first stage, and that work appears to be progressing well. However, there has been little public discussion about the development of the first- and second-stage hardware built around the Miranda engine. Like Rocket Lab, Firefly and Northrop Grumman are also working with carbon-composite structures, which could present additional challenges.

The partnership between Firefly, a newer space company, and Northrop Grumman, a traditional aerospace company, could also create friction. Rocket development involves considerable uncertainty, making it difficult to predict Eclipse’s progress with confidence. For now, the available information supports a pessimistic outlook.

Expected launch debut: No earlier than 2029