“This is the backbone of Artemis III,” NASA’s Lori Glaze said regarding the delivery of the core component for the rocket, a comment that makes sense because the recently delivered component is less of a photo op than the centerpiece of a reoriented lunar program. NASA has now brought the upper four sections of the Space Launch System (SLS) core stage from the Michoud Assembly Facility in Louisiana, a journey of about 900 miles by sea using the agency’s Pegasus barge to arrive at the Kennedy Space Center. Once assembled with the engine section, the full SLS will measure 212 feet and act as the launch support for Artemis III, which now focuses on orbital demonstrations instead of going directly for the Moon landing.
This development is more significant than the delivery. Unlike previous missions, Artemis III does not primarily aim to deliver crew members to the Moon anymore. This mission now seeks to perform demonstration operations in Earth’s orbit, namely, rendezvous and docking procedures involving Orion and the lunar landers of commercial companies such as SpaceX and Blue Origin, thereby testing the equipment chain required for further missions. Practically speaking, this development makes integration an important part of the mission because the core stage of the SLS should be ready, Orion should be ready, and the docking architecture should be able to accommodate non-NASA-built spacecraft.
The core stage is the main body of the SLS that holds the propellant, avionics, and computer hardware for flight, and its significance extends beyond structural importance. As reported by NASA, there are two tanks inside the core stage that contain a total of more than 733,000 gallons of supercooled liquid oxygen and hydrogen that feed the four RS-25 engines to launch the craft into space. The RS-25 engines have been used on Shuttles, but their utilization on SLS is a challenging task since they operate under increased conditions. According to NASA, the RS-25s used for SLS are running at 109 percent of their power level since the beginning, having upgraded control systems, new thermal insulation, and having proven themselves during a long test program at the Stennis Space Center.
It explains why this event is important. The SLS core stage is not only the tank section awaiting assembly, but it is also the heart of four of the most extensively tested large rocket engines in NASA’s history, each of them working with a propulsion system built on Shuttle technology but modified for the new purpose. During the maiden voyage of SLS (Artemis I), NASA has reported that four RS-25 engines produced more than two million pounds of vacuum thrust and performed very well in accordance with the expectations, thus strengthening the case for maintaining RS-25 in the Artemis missions.
Finally, there is an industrial side to it. The vessel delivering the SLS core stage was originally designed for transporting shuttle external tanks and then enlarged to accommodate the SLS core stage, which became the longest piece to be shipped via NASA barges. This fact is representative of the larger context in which Artemis operates. This program relies on the coordination of legacy propulsion technologies, transportation systems modified for the need, manufacturing processes, and private space vehicles developed in parallel on compatible timetables.
Upon arrival at Kennedy, the core stage will be transferred into the Vehicle Assembly Building for the final fitting with the engine section. It will lead to an iconic picture, that of an enormous rocket part being delivered to Florida. However, the mission has changed, and the SLS core stage delivery represents the point where Artemis becomes a systems validation mission.