"Chief among the agency’s concerns is the development of Starship. SpaceX must not only demonstrate the capability to fly the vehicle safely, the company must master the ability to transfer and store cryogenic fuel in orbit, so that a Starship can launch into orbit, be refueled, and then fly out to lunar orbit to rendezvous with Orion.

Before the Artemis III mission, SpaceX will likely fly dozens of Starship test flights; the campaign to fuel a Starship in orbit alone will take about 10 tanker flights, said Jessica Jensen, a senior engineer at the company. SpaceX must also demonstrate an uncrewed test landing on the Moon and an unprecedented launch of Starship from the lunar surface using cryogenic fuels—liquid oxygen and methane."