Impulse Space, the startup founded by former SpaceX propulsion leader Tom Mueller to build highly agile spacecraft, has secured $500 million in Series D funding this week. The company plans to use the capital to hire up to 200 new employees. The investment round was led by 137 Ventures and BANNER VC, with additional backing from Founders Fund, Lux Capital, and Linse Capital. This surge of interest reflects growing investor enthusiasm for space and defense technology, as the U.S. government increases spending on national security initiatives and SpaceX prepares for its public offering.

Impulse Space specializes in in-space mobility. The company has developed a highly maneuverable platform called Mira, specifically designed for U.S. Space Force customers. It is also building Helios, a vehicle intended to rapidly transport satellites to high orbits after they are deployed in lower orbits closer to Earth. While the company’s software teams are beginning to incorporate AI coding tools, CEO Tom Mueller noted that deep learning models are not yet reliable for solving real-world engineering challenges.

Mueller, who joined SpaceX as its 13th employee in 2003, was responsible for creating computer simulations to evaluate the company’s engine designs. "I considered it success if I got within 20% of the right answer, because the simulations were just not that good," he recalled. "They’ve improved, but they’ve not improved that much, and so there’s not really any substitute for designing the thing, analyzing the thing, building it, and then getting it on the test stand."

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Mueller believes that AI tools for hardware design may take longer to develop because suitable training data is scarce, unlike the vast amounts of text and code available for training large language models. "If you want to go, say, find the best designs for a turbo pump seal package in the world, you’re not going to find those online," he pointed out.

Impulse initially focused on propulsion systems and later evolved into building complete spacecraft, which required expanding its expertise with engineers skilled in vehicle structures and flight computers. The company recently opened an office in Colorado, partly because aerospace talent now has more options—engineers can find work in Seattle, Denver, or Texas, rather than being limited to Los Angeles.

Next on the horizon for Impulse is another launch of its Mira spacecraft, which completed its third flight late last year. That mission encountered a problem with its navigation system, causing the craft to consume much of its propellant early on. Mueller said the company is preparing a new Mira mission, expected to launch before the end of the year.