WASHINGTON: A SpaceX mission is set for launch Saturday with two passengers on board, leaving two seats empty to return the American astronauts who have been stranded for months on the International Space Station (ISS), Nasa said.

The launch of the Falcon 9 rocket is scheduled for 1:17pm (1717GMT) from Cape Canaveral, Florida.

It will use a new launch pad, the pad's first use for a crewed mission.

On board will be Nasa astronaut Nick Hague and Russian cosmonaut Alexander Gorbunov.

When they return from the space station in February, they will bring back the two space veterans — Butch Wilmore and Suni Williams — whose stay on the ISS was prolonged for months by problems with their Boeing-designed Starliner spacecraft.

The newly developed Starliner was making its first crewed flight when it delivered Wilmore and Williams to the ISS in June.

They were supposed to be there for only an eight-day stay, but after problems with the Starliner's propulsion system emerged during the flight there, Nasa was forced to weigh a radical change in plans.