NASA's Artemis 3 Rocket to Launch With Empty Space Where Upper Stage Used to Be

NASA has announced that the Space Launch System for the Artemis 3 mission will launch without an upper stage, replacing it with what the agency calls a “spacer” - effectively a metal dummy that takes up space and does nothing but match the dimensions of the missing hardware.

In a May 13 update, NASA confirmed the SLS will fly with an inert spacer built at Marshall Space Flight Center in place of the Interim Cryogenic Propulsion Stage (ICPS). The spacer has the same dimensions and interfaces as the ICPS, but will not, as the name suggests, propel anything.

The change stems from a February announcement that Artemis 3 - originally planned as the first crewed lunar landing attempt since 1972 - will instead remain in low Earth orbit to rendezvous with lunar lander prototypes from Blue Origin and SpaceX. NASA also scrapped development of the Block 1B version of the SLS, which would have used the larger Exploration Upper Stage, leaving the agency to scramble for alternatives.

Since the ICPS - derived from the Delta 4 upper stage - is no longer in production, NASA said March 6 it would eventually use the Centaur upper stage from United Launch Alliance’s Vulcan rocket. For now, the spacer allows NASA to save the last remaining ICPS for Artemis 4, the first actual crewed landing attempt planned for 2028, buying time to adapt the Centaur for SLS use starting with Artemis 5.

Without the ICPS, the Orion spacecraft will use its own propulsion to circularize its orbit at 463 kilometers with an inclination of 33 degrees, according to a May 7 request for information about alternative communications systems.

NASA stated the Artemis 3 mission will “test rendezvous and docking capabilities” between Orion and Blue Origin’s Blue Moon Mark 2 lander and SpaceX’s Starship lander. But the agency released few details - including whether astronauts will actually enter either lander. “Informed by Blue Origin and SpaceX capabilities, NASA also is defining the concept of operations for the mission,” the agency said. “While some decisions are yet to be determined, astronauts could potentially enter at least one lander test article.”

Complicating matters further, the mission will require three separate launches: the SLS carrying Orion, plus independent launches of the two landers. “For the first time, NASA will coordinate a launch campaign involving multiple spacecraft integrating new capabilities into Artemis operations,” said Jeremy Parsons, acting assistant deputy administrator for Moon to Mars at NASA.

NASA noted Artemis 3 will last longer than Artemis 2, which splashed down after just over nine days. But the agency has yet to select a crew, decide how the Axiom Space lunar spacesuit might be tested, or commit to a launch date beyond “sometime next year” - previously mid-2027, but now possibly late 2027.

In other words, the rocket that was supposed to return humans to the Moon will instead fly with a placeholder and test-dock with landers that may or may not let astronauts inside. Progress!