The US National Aeronautics and Space Agency (Nasa) announced on Tuesday that the stacking of the two solid rocket boosters for the Artemis I mission had been completed. Each booster was composed of ten booster segments and a nose assembly, and both had been erected by large cranes on the mobile launcher platform in the Vehicle Assembly Building at the Kennedy Space Centre in the US state of Florida.

Artemis is Nasa’s new crewed space exploration programme, which will take astronauts back to the Moon (including the first woman to go there) and beyond. Artemis I will, however, be an uncrewed test flight.

The assembly process began with the placement of the first segment on the mobile launcher on November 21 last year, with the final nose assembly being put in place on March 2. The remaining work on the boosters comprises the installation of the remaining electrical instrumentation and pyrotechnics. This will be followed by a series of tests of the boosters’ systems.

The boosters will augment the core stage of what Nasa designates the Space Launch System (SLS), which will be the most powerful rocket in the world. During launch, the SLS will produce about 356 kN of thrust. 

“Seeing the Space Launch System solid rocket boosters stacked completely on the mobile launcher for the first time makes me proud of the entire team especially the Exploration Ground Systems crew at Kennedy who are assembling them and also the teams at Marshall (Space Flight Centre) and Northrop Grumman who designed, tested and built them,” affirmed Nasa Marshall Space Flight Centre SLS boosters manager Bruce Tiller. “This team has created the tallest, most powerful boosters ever built for flight, boosters that will help launch the Artemis I mission to the Moon.”

When it is delivered to Kennedy, the SLS core stage will be stacked on the mobile launcher, between the boosters. The core stage is powered by four RS-25 liquid-fuelled engines. The core stage was subjected to a test firing or “hot fire” (that is, all its engines were ignited at the same time) at Nasa’s Stennis Space Centre on January 16, but this did not last as long as planned. Consequently, following the inspection and refurbishing of both the SLS and the test stand, and the analysis of data collected from the first test firing, a second hot fire should take place during the middle of this month.