Impulse Space, a startup founded by SpaceX engine guru Tom Mueller to build highly-maneuverable spacecraft, announced a $500 million Series D this week that it will use to hire as many as 200 new employees.

The round, led by 137 Ventures and BANNER VC, with participation from Founders Fund, Lux Capital, and Linse Capital, reflects investor interest in space and defense tech as the U.S. government hurls cash at national security problems and SpaceX gears up for its IPO.

Impulse is focused on in-space mobility. The company has developed a highly maneuverable platform called Mira that is targeted at U.S. Space Force buyers. It’s also building Helios, a vehicle designed to carry satellites rapidly to high orbits after they are dropped off in space closer to Earth.

President and COO Eric Romo told TechCrunch that the new capital will help the company build and test more space vehicles and emphasized the company’s hiring plans at a time when aerospace talent is in high demand.

While the company’s software teams are adopting AI coding tools, Romo said that when it comes to solving engineering problems in the real world, deep learning models aren’t quite ready for prime time. As the 13th employee at SpaceX back in 2003, Romo’s job was creating computer simulations of the company’s engine design to assess its performance.

“I considered it success if I got within 20% of the right answer, because the simulations were just not that good,” Romo said. “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.”