March 5th 2024 In-Person Event

Presentation Topic:

The Mobile Launcher 2 (ML2) is a new rocket support structure developed in conjunction with NASA’s Artemis Program. The 380-foot tall ML2 tower will be used to assemble, transport, and launch the largest Block 1B and Block 2 configurations of NASA’s Space Launch System (SLS) rocket and Orion spacecraft. It is significantly larger and supports a vehicle nearly 1 million pounds heavier than its predecessor Mobile Launcher 1 (ML1). Both ML1 and ML2 employ the same Crawler Transporter (CT) and are weight constrained by its lifting capacity.

As a portable structure, ML2 must interface with existing NASA infrastructure at the Kennedy Space Center, including three different facilities and the CT which moves it between these facilities. The Block 2 configuration of SLS is one of the largest rockets currently in the world, weighing up to 6 million pounds fully fueled. It will blast ML2 with 9.5 million pounds of thrust from its two solid rocket boosters and four RS-25 engines. Critical components of the structure will be exposed to plume and vibro-acoustic loading, reaching pressures of 150psi and temperatures of 2,200 °F. Concurrently, half a million pounds of water is passing through the structures sound suppression system and 400,000 gallons of water is released onto the structure in 40 seconds. The extreme environment of the launch event controls much of the structural design. Even in the absence of a launch, the coastal Florida landscape provides significant design and material challenges from hurricanes and one of the world’s most corrosive environments.  In all 6114 load combinations are evaluated in the ML2 Global Analysis.

The most impactful design considerations required producing a lightweight structure that complied with stringent stiffness requirements governing the dynamic interaction between the spacecraft and the tower. Advanced analysis leveraging virtual work techniques were utilized to identify and optimize critical members in the tower. High strength API steel pipe is used for tower columns and vertical bracing similar to off-shore rigging platforms. Complex piping connections are manufactured as steel castings to simplify design, reduce weight, and improve joint stiffness. The tower’s construction sequence is built into the analysis model to capture residual stresses from self-weight and accurately trace dead load distribution through the different support conditions.

The ML2 structural design is backed by a robust analysis validating the structure’s ability to support the great number of loads and conditions necessary to meet the goals of the Artemis Program. ML2 is the launch point to return humans to the lunar service, establish a lunar outpost, and lunar gateway to test and qualify technologies needed to travel to Mars.