The private equity firm AE Industrial Partners (AEI) on Tuesday said its portfolio company American Pacific Corp., which produces specialty chemicals for the aerospace, defense and other markets, has made a minority investment in Frontier Aerospace, which specializes in space propulsion systems.

Terms of the deal were not disclosed.

“With our investment in Frontier, we now have a strategic partner in next-generation, in-space liquid propulsion technology,” Hal Murdock, American Pacific’s CEO, said in a statement. Jim McKinnon, founder and president of Frontier, said that the investment provides “additional resources to take advantage of the tremendous interest in today’s space industry, combined with the added benefit of their deep defense industry expertise. We also look forward to leveraging AEI’s relationships and intimate understanding of aerospace and defense’s unique challenges.”

American Pacific, which is based in Utah, provides oxidizers for solid rocket propellant used in solid rocket motors for space launch and military missiles.

Frontier, which is based in California, has expertise and capabilities in liquid rocket propulsion development, liquid propulsion rocket system design, rocket engine development and test support, mechanical design, computational fluid dynamics analysis, combustion devices design and analysis, and electromagnetic analysis.

Frontier’s products are used in defense, deep space applications, lunar landers, collision avoidance, space transportation, space tourism and earth observation satellites, AEI said. The company’s propulsion systems are planned for two lunar landers as part of NASA’s Commercial Lunar Payload Services mission.