Boeing has announced that the Exploration Upper Stage (EUS) for Nasa’s Space Launch System (SLS) rocket passed the critical design review (CDR).

The milestone confirms that the EUS’s design meets requirements for future missions in deep space environments and ensures the safety of astronauts.

EUS prime contractor Boeing has started fabrication activities to support the development of first EUS.

It will produce and assemble the upper stage at Nasa’s Michoud Assembly Facility in New Orleans.

The EUS will power SLS rocket in early flight until being taken over by the upper stage.

Using staged propulsion, the rocket will support the launch of Nasa’s Orion spacecraft, astronauts and supplies to the Moon and beyond.

Boeing EUS programme manager Steve Snell said: “Nasa’s SLS Block 1B with the EUS is capable of sending astronauts and essential supporting cargo to the moon and beyond.

“EUS was designed for crewed flights from the beginning, and the additional lift capability that comes with the EUS requires fewer flights to enable a sustained human presence in deep space sooner and more safely.

“The Moon is 238,000 miles from Earth, and Mars at its closest has been 35 million miles away. Transporting crews in the fewest flights, for shorter durations, is the safest approach to human deep-space travel.

“Only the EUS-powered SLS can carry the Orion, along with the necessary mission cargo, in one launch to the Moon – or beyond.”

Powered by Boeing/United Launch Alliance Interim Cryogenic Propulsion Stage and one RL-10 engine, the Block 1 variant of SLS will take an uncrewed Orion spacecraft on a test flight to the moon.

Nasa aims to land the first woman and the next man on the Moon in 2024 under the Artemis programme.

Last month, Nasa completed the installation of three spacecraft adapter jettison fairing panels into Orion’s European Service Module.