After years of delays, the first SLS core stage is complete
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NASA Administrator Jim Bridenstine talks about the progress of the Artemis program with the first completed SLS core stage behind him. Credit: NASA/Bill Ingalls
The first flight core for the long-delayed Space Launch System is finally complete and ready for final testing ahead of the Artemis 1 mission.
On Dec. 9, 2019, NASA unveiled the 8.4-meter-wide, 64.6-meter-long stage to members of the media at the agency’s Michoud Assembly Facility in New Orleans. The rocket core — the largest ever produced by NASA — is slated to be used for the Artemis 1 mission in early 2021, which will send an unpiloted Orion spacecraft around the Moon.
Credit: NASA/Bill Ingalls
"The completion of the SLS core stage is a major milestone and a testament to American enterprise and ingenuity," said NASA Administrator Jim Bridenstine during an event in front of the core. "With more than 1,100 large and small businesses in 44 states contributing to the design and assembly, the SLS rocket will empower America to achieve the Artemis program’s goal of landing the first woman and next man on the Moon by 2024."
While it is the largest piece of the full 98-meter-tall SLS rocket, the core itself is composed of several smaller sections: the forward skirt, liquid oxygen tank, intertank, liquid hydrogen tank and engine section.
Initially, the plan was to assemble the sections of the core vertically starting with the engine section. However, its completion was taking longer than anticipated.
Because the engine section was in the critical path for assembly, NASA and Boeing worked to find a solution to continue assembling the core while the engine section was still being built.
“Earlier this year, NASA revised its assembly plan to connect the stage horizontally rather than vertically,” said John Honeycutt, the SLS Program Manager, in a NASA news release. “By doing so, NASA advanced its timeline so that our teams could meet our goal to complete assembly on the core stage by the end of the year. It was great to have for employees, stakeholders and the public to join us in the factory to mark the occasion.”
The first competed SLS core stage. Credit: NASA/Jared Lyons
With the core complete and four space shuttle-era RS-25 engines installed, NASA plans to move giant stage to a barge called Pegasus to transport it to the Stennis Space Center to prepare it for a full-duration “Green Run” test.
This test will involve placing the giant rocket stage onto the B-2 test stand to fire all four of its RS-25 engines for roughly 8.5 minutes — the time it’ll take for the vehicle to get into orbit.
Once completed, the rocket will be reloaded onto Pegasus and shipped to the Kennedy Space Center in Florida where it will be integrated with the rest of the components of the Artemis 1 mission on top of the mobile launcher inside the Vehicle Assembly Building. This is currently expected to occur sometime in the second half of 2020.
While the Artemis 1 hardware is getting its moment in the spotlight, the pieces are beginning to come together for the Artemis 2 mission.
Also at Michoud are the structures that will form the second SLS core stage, which will be used for the Artemis 2 mission to send a crew of four around the Moon as early as late 2022. According to NASA, some components for the Artemis 3 mission are also at the facility.
If everything goes according to plan, NASA hopes to land the first woman and the next man on the Moon by the end of 2024.
Earlier this year, NASA announced it was beginning the process of ordering more SLS core stages for as many as 10 Artemis missions. The agency said it was working with Boeing, the rocket’s prime contractor, to lower the cost of the vehicle as production matures.
The Artemis 1-3 missions will fly atop a Block 1 SLS rocket, which sports an Interim Cryogenic Propulsion Stage — a modified upper stage utilized on Delta IV rockets. Staring with Artemis 4 in 2025, NASA expects to utilize the more powerful Exploration Upper Stage, also to be built by Boeing, increasing the amount of mass that can be sent to the Moon from 26 metric tons to 37 metric tons.
