Common Questions

What is the Interim Cryogenic Propulsion Stage?

The ICPS is the upper stage that fires after SLS core separation to send Orion toward the Moon, then detaches and is discarded.Source: NASA Artemis II mission overview

Why did Artemis II fly close to the ICPS?

The crew used the detached ICPS as a proximity target to practise manual close-approach manoeuvres needed for future lander docking.Source: NASA Artemis II mission report

How close did Orion get to the ICPS?

The crew flew Orion to within 10 metres during a 70-minute demonstration.Source: NASA Artemis II mission report

Background

The Artemis II crew flew Orion to within 10 metres of the detached ICPS during a 70-minute manual proximity-operations demonstration, validating close-approach handling ahead of future lander rendezvous.

The ICPS is derived from the Boeing Delta IV upper stage. After the SLS core stage separates, it provides the trans-lunar injection burn that sends Orion toward the Moon, then detaches and is disposed of in deep space. It stands approximately 13.7 m tall and burns liquid hydrogen and liquid oxygen.

Using the discarded ICPS as a proximity target was an engineering workaround: Artemis II has no dedicated rendezvous target. The exercise validates manual docking skills needed to dock with the Human Landing System on Artemis III, making the test a rehearsal for the Moon landing itself.