NASA Updates ML-1 for Artemis II Mission and Continues Construction of ML-2 for SLS Block IB

NASA is making significant upgrades to its Mobile Launcher (ML) in preparation for the Artemis missions. Mobile Launcher-1 (ML-1) is currently undergoing testing and validation at Launch Complex 39B, while Mobile Launcher-2 (ML-2) is being constructed for future missions. In an interview with NASA Spaceflight, David Sumner, Senior Project Manager for NASA’s Exploration Ground Systems (EGS), discussed the modifications being made to ML-1.

One of the key upgrades to the ML deck is the improvement of the rainbird heads and the Ignition Overpressure Protection and Sound Suppression (IOP/SS) systems. Sumner explained that the rainbird heads have been modified to enhance water flow and coverage on the deck. Additionally, one of the rainbird heads has been completely redesigned to improve water flow dispersion. The other four rainbird heads have been fitted with deflectors to direct the water away from the cameras on the deck.

Unlike the previous use of red water bags during the Shuttle program, there are no plans to implement such measures for Artemis missions. Sumner emphasized that the focus is on protecting the deck and improving imagery. Blast plates on the ML deck will also be replaced and strengthened to withstand high blast pressures. Water dams will be installed to redirect water flow and improve imagery. These changes may include modifications in thickness, strength, and structural reinforcements.

Sumner acknowledged that some damage to the blast plates was expected, as they were considered sacrificial. New blast plates are currently being installed, and efforts are being made to improve their durability based on lessons learned from Artemis I. The repairs to the ML deck are expected to be completed by Artemis II or III.

While no major modifications have been made to the liquid hydrogen systems on the ML, repairs have been made to any damage incurred during previous launches. Lessons learned from wet dress rehearsals and launch counts are being addressed by the operations team. However, efforts are being made to harden the Gaseous Nitrogen (GN2) system on the ML to avoid challenges faced during Artemis I. Damaged GN2 lines have been replaced, and additional shielding and flex connections are being considered to improve the system’s performance.

The elevators on the ML have also required substantial refurbishment. Engineering teams are working on a design to harden the elevator systems and blast doors to prevent damage during launches. The design is expected to be implemented in the coming weeks.

To support crew missions, ML-1 has been modified with an Emergency Crew Escape System. In the event of an on-pad emergency, crew members would evacuate the ML and pad using slide wire baskets. The fabrication of the baskets is progressing well, and factory acceptance testing is underway. Testing of the baskets will involve various scenarios and failure modes to ensure their reliability. The goal is to complete testing within 90 days.

Another important aspect of the upgrades is certifying the Crew Access Arm (CAA) for Artemis II. Over 100 swing tests will be conducted to certify the CAA, and teams are preparing to start the tests in the next few weeks. Once certification is complete, the ML will be needed back in the Vehicle Assembly Building (VAB) for stacking.

Overall, the modifications being made to ML-1 are aimed at enhancing safety, protecting the deck, and improving imagery for future Artemis missions. The upgrades include improvements to the rainbird heads, blast plates, GN2 system, elevators, and the addition of an Emergency Crew Escape System. These upgrades will ensure that ML-1 is ready for Artemis II and beyond.