NASA has selected Elon Musk's private aerospace company SpaceX to provide launch services for two major components of the Gateway that will serve as a way station for future Moon missions.

As part of the contract, SpaceX will provide launch services for NASA's Power and Propulsion Element (PPE) and Habitation and Logistics Outpost (HALO), the foundational elements of the Gateway.

The total cost to NASA is approximately $331.8 million, including the launch service and other mission-related costs, the US space agency said on Wednesday.

As the first long-term orbiting outpost around the Moon, the Gateway is critical to supporting sustainable astronauts missions under the agency's Artemis program.

After integration on Earth, the PPE and HALO are targeted to launch together no earlier than May 2024 on a Falcon Heavy rocket from Launch Complex 39A at NASA's Kennedy Space Centre in Florida.

The PPE is a 60-kilowatt class solar electric propulsion spacecraft that also will provide power, high-speed communications, attitude control, and the capability to move the Gateway to different lunar orbits, providing more access to the Moon's surface than ever before.

The HALO is the pressurized living quarters where astronauts who visit the Gateway, often on their way to the Moon, will work.

It will provide command and control and serve as the docking hub for the outpost.

HALO will support science investigations, distribute power, provide communications for visiting vehicles and lunar surface expeditions, and supplement the life support systems aboard Orion, NASA's spacecraft that will deliver Artemis astronauts to the Gateway, NASA said.

About one-sixth the size of the International Space Station, the Gateway will function as a way station, located tens of thousands of miles at its farthest distance from the lunar surface, in a near-rectilinear halo orbit.

It will serve as a rendezvous point for Artemis astronauts travelling to lunar orbit aboard Orion prior to transit to low-lunar orbit and the surface of the Moon.