This New SpaceX-Linked Startup Just Scored $100M to Build Hypersonic Weapons

With geopolitical tensions rising, particularly in the Indo-Pacific, the demand for advanced defence technology is stronger than ever. Castelion, a California-based startup founded by SpaceX veterans, is stepping up to meet that need, securing a $100 million Series A funding round to develop and mass-produce hypersonic long-range strike weapons.

The El Segundo-based company is focused on creating what it describes as “affordable, mass-produced hypersonic long-range strike weapons” designed to serve as a non-nuclear deterrent. These weapons are engineered to travel at speeds exceeding Mach 5 while maintaining manoeuvrability, making them difficult to intercept. As China and Russia advance their own hypersonic capabilities, the Pentagon is prioritising the development of similar systems to maintain a strategic edge.

Big Investors Back Hypersonic Ambitions

The funding round was led by Lightspeed Venture Partners, with participation from Andreessen Horowitz (a16z), Lavrock Ventures, Cantos, First In, BlueYard Capital, and Interlagos. The deal also included $30 million in venture debt from Silicon Valley Bank, with the final close expected in February.

This investment is the latest in a series of high-profile deals in the defence technology sector. Andreessen Horowitz, for example, has been increasingly active in defence tech, leading a $175 million Series B last year for autonomous surface vessel maker Saronic. Other major funding rounds in the sector include Chaos Industries’ $145 million raise and Firehawk Aerospace’s recent $60 million Series C.

Hypersonic Innovation at Speed

Founded in 2022 by Sean Pitt, former director of commercial sales at SpaceX, and Andrew Kreitz, former senior finance manager at SpaceX, Castelion is taking an unconventional approach to missile development. Instead of relying on traditional defence industry timelines, which can stretch over decades, the company aims to field its weapons in a matter of months.

To achieve this, Castelion is leveraging techniques commonly used in the commercial space industry—such as vertical integration, iterative design cycles, and agile manufacturing. The company has already designed and tested its own solid rocket motors, low-cost missile avionics, and hypersonic thermal protection materials. It has successfully conducted three internal flight tests in under a month and plans further long-range demonstrations throughout 2025.

Building the Future of Defence

The newly secured funding will be used to expand prototype testing, scale up manufacturing, and prepare for a full capability demonstration of Castelion’s first hypersonic weapon. The company’s goal is to produce these weapons at a cost and speed that makes them a viable, large-scale deterrent – an essential capability as the U.S. and its allies seek to maintain a strategic advantage in modern warfare.