Space company Virgin Galactic has formed an agreement with Aurora Flight Sciences, a Boeing company, to make two of its next generation of motherships.

Virgin’s motherships are air launch carrier aircraft that carries spaceships to a release altitude of approximately 50,000 ft.

“Our next generation motherships […] will be faster to produce, easier to maintain and will allow us to fly substantially more missions each year,” said Virgin Galactic CEO Michael Colglazier. “Supported by the scale and strength of Boeing, Aurora is the ideal manufacturing partner for us as we build our fleet to support 400 flights per year at Spaceport America.”

Aurora plans to manufacture the craft at its facilities in Mississippi and West Virginia, with the first new mothership expected to enter service in 2025, the same year Virgin Galactic’s first Delta-class spaceship could begin revenue payload flights.