NASA and its advisory bodies remain concerned about the low flight rate planned for its crewed Orion spacecraft and Space Launch System (SLS) rocket, but the space agency doesn’t have enough vehicles to fly more often this decade. Hardware to launch only two more SLS vehicles is available until development of the Exploration Upper Stage (EUS) upgrade is completed, which isn’t expected to be ready to launch on Artemis IV until late 2028 at the earliest.
Following the Artemis II lunar flyby test flight planned late next year, the Artemis III Orion and crew could be the only one flying to the Moon in the following four years, but NASA still has the option to buy more Interim Cryogenic Propulsion Stages (ICPS) built by United Launch Alliance and continue flying the current Block 1 version SLS. ULA has noted that the ICPS production line will remain open until next year, when the Delta IV that ICPS is derived from retires; however, NASA once again affirmed its choice not to buy any more ICPS units in mid-September.