Startup Castelion Raises $100 Million for Hypersonic Strike Weapons
The debt-and-equity funding is the latest sign venture capitalists have embraced the superfast weapons
Silicon Valley’s enthusiasm for superfast weapons has picked up speed, with defense-tech startup Castelion raising $100 million through debt and equity to build hypersonic missile systems.
The company is vying to sell long-range strike weapons to the U.S. military. Castelion is part of an increasingly well-funded sector of venture-backed defense companies. Many are hopeful the new Trump administration and Elon Musk’s influence with the president will yield more government contracts for startups.
“There will be more support for awarding contracts to nontraditional players,” said Sean Pitt, Castelion’s co-founder. The administration has given the Pentagon “the freedom to lean into new companies.”
Castelion raised $70 million from venture investors and $30 million in debt to help finance a new manufacturing plant to add to its facilities in California and Texas. The funding round, led by Lightspeed Venture Partners, brings the company’s total funding to $114 million. Andreessen Horowitz also invested.
A number of startups are focused on building hypersonic-speed aircraft as well as launching services and engines. Castelion is pitching an entire weapons system. It builds the whole aircraft, from the solid rocket motors to the electronics. It may venture into building the warheads, although now the company buys them.
The Defense Department has considered hypersonics a national-security imperative for more than a decade. Despite spending billions of dollars on the effort, it has failed to develop battlefield-ready technology.
Castelion says its frequent flight tests, quick engineering upgrades and economical manufacturing will produce cheaper and better hypersonic weapons. It does about three test flights a month in the California desert.
Hypersonic weapons, defined as a projectile that flies at least five times the speed of sound, can be launched from great distances, maneuver and evade most air defenses. They became a top Defense Department priority during President Trump’s first administration. A 2021 test flight by China, which launched a weapon that circled the globe at 20 times the speed of sound or faster, alarmed Washington. Last year, the Biden administration added hypersonics to its list of critical and emerging technologies.
The Army missed its goal of fielding a hypersonics weapon in 2023 after testing failures, and pushed its deadline back. The Army didn’t respond to a request for comment.
A hypersonics program the Air Force estimated would become operational in 2022 hasn’t materialized, and the service is working on another program that it says will produce a weapon in 2027. An Air Force spokeswoman said the service is working on other programs and collaborating with startup defense companies and providing them with opportunities to demonstrate their technology.
Many in the industry hope Trump’s shake-up of Washington agencies, the technology industry’s coziness with the president, and influence from Musk—himself the founder of the largest venture-backed defense-tech company—will bring attention and money to hypersonics.
Castelion’s three founders were each previously in senior positions at SpaceX, and roughly half the company’s 60 employees joined from Musk’s firm. The founders said they haven’t had contact with Musk since starting Castelion in 2022.
Castelion said it would have a finished product ready for the military in 2027 and will have its first hypersonic-speed test flight for its weapon this summer. It has been awarded more than $22 million in federal government contracts, most from the Air Force.