Years behind schedule, massive steel trusses arrive for new Artemis mobile launcher

NASA’s Space Launch System that set the record for most powerful rocket to ever blast into orbit last November on the Artemis I mission left its mobile launcher in need of some repair before it can be used again.

While work continues to get that launcher ready for next year’s crewed Artemis II mission, an even bigger mobile launcher will be needed for future launches, and NASA just got its hands on the first major steel trusses so it can begin construction on mobile launcher 2 (ML-2) later this summer.

The need for a second mobile launcher is driven by what will be a version of SLS that’s 40 feet taller called the Block 1B. The height increase is due to SLS getting rid of what’s called the Interim Cryogenic Propulsion Stage (ICPS) used to propel the Orion space capsule to the moon in favor of the more powerful and roomier Exploration Upper Stage beginning with Artemis IV, a mission currently on NASA’s roadmap for no earlier than 2028.

ML-2 is being constructed by primary contractor Bechtel National Inc. under the guidance of NASA’s Exploration Ground Systems team based at KSC. Thursday’s steel truss arrival was only the third of 43 set to make their way to KSC as the behemoth structure takes shape.

When finished, the ML-2 will stand about 355 feet tall and weigh 11.3 million pounds. It will be able to support the Block 1B version as well as a planned Block 2 version of SLS that is planned to have even more power at liftoff than the first Artemis missions, which produce 8.8 million pounds of thrust on liftoff.

Bechtel was awarded the original contract to construct ML-2 in 2019 for $383 million with a completion originally promised by spring 2023. Cost increases and design delays piled on through 2022 prompting NASA’s Office of the Inspector General to audit the program. Its findings released last June showed the total projected cost was already expected to hit $960.1 million, or 2 1/2 times more than originally planned.

Delivery now is officially delayed until October 2025, but the audit suggests even that date won’t be attainable.

“We expect further cost increases as inevitable technical challenges arise when ML-2 construction begins,” the audit reads. “Given the time NASA requires for additional testing once the structure is delivered, the earliest the ML-2 will be available for Artemis IV is November 2026.”

The audit further stated that an independent review team determined costs would balloon to $1.5 billion and a delivery date of December 2027.

That is one logistical reason Artemis IV is not on NASA’s calendar until as many as three years after its planned Artemis III mission, which would feature the first woman and next man on the moon. That flight is currently slated for no earlier than December 2025, although it too could slip as it relies on SpaceX to have a working version of its in-development Starship as a lunar lander.

The other logistical delay would be the readiness of the hardware to build out NASA’s planned lunar space station called Gateway, which is central to the mission plans for Artemis IV and beyond. In those missions, Orion would dock with Gateway before any missions down to the lunar surface.

ML-2 should be able to withstand the 6 million pound weight of SLS when loaded with its fuel, and is designed to provide power, data, remote monitoring, control, propellants, fluids, gasses, sound suppression, imagery and communications for launch.

With the addition of the Exploration Upper Stage for both Block 1B and Block 2 versions of SLS, the ML-2 will need two additional swing arms. Since the ML-2 is taller, by about 7 feet, it will have to deal with higher structural design loads on launch, but will still be small enough to fit into KSC’s Vehicle Assembly Building.

The base will be 133 feet wide, 158 feet long and 25 feet tall supported by six 25-foot-tall pedestals whether it’s parked at the VAB, Launch Pad 39-B or at the mobile launcher park site, where ML-1 is currently being upgraded to support humans on its next launch.

Both will have a Crew Access Arm and Emergency Egress System, at different heights since Orion will be higher up on the Artemis IV missions, about 317 feet above the ground. That’s the height from which astronauts and other support crew would have to slide down to safety from through one of four large baskets able to hold up to five people. The baskets travel down four large cables to staged vehicles for escape from the pad area.

Unlike the Space Shuttle Program, which had a tower permanently constructed at the launch pad, the mobile launchers require the emergency egress systems to be assembled and disassembled between every SLS launch.