SLS ML at 39B – Part One

The mobile launcher (ML) is the ground structure that will be used to assemble, process and launch NASA’s Space Launch System (SLS) rocket and Orion spacecraft from Launch Pad 39B at Kennedy Space Center for missions to deep space destinations, such as the Moon, Mars and beyond.

The SLS, topped by the Orion spacecraft, will be stacked atop the mobile launcher while inside the Vehicle Assembly Building (VAB). Afterward the mobile launcher will be moved by the crawler-transporter over four miles away to Launch Complex 39B for launch. The nearly 380-foot-tall structure is equipped with the crew access arm and several umbilicals that will provide power, environmental control, pneumatics, communication and electrical connections to the rocket and spacecraft during processing and launch. Several other umbilicals will provide fuel and stability to the rocket on the surface of the mobile launcher’s deck. After the SLS launches, the mobile launcher will be returned to the VAB in preparation of having another SLS rocket stacked on it.

These images taken over the last few years show the final construction of the mobile launcher and, in Part 2, its move to Launch Complex 39B for fit checks.

A large model displays the Space Launch System rocket on the mobile launcher.

This model view shows the SLS and the mobile launcher gantry with several of the umbilicals reaching out to the rocket including, at top, the crew access arm through which astronauts will cross over to enter the Orion spacecraft. In the background is the Exploration Flight Test-1 Orion spacecraft that flew a four-hour test flight approximately 22,000 miles into space and back to test its systems and heat shield before astronauts fly in it.

Morning at Kennedy Space Center. The bright Sun lights up the VAB and mobile launcher sitting at its construction site.

Various views of the mobile launcher at its construction site.

Total height above ground: 380 feet
Tower: 40 feet square, about 355 feet tall
Tower floor levels: every 20 feet for personnel access to vehicle and ground support equipment

Approximate weight: 10.5 million pounds (approximate weight when complete)

The newly added Crew Access Arm sticks out to the left near the top of the mobile launcher gantry. It is through this arm that astronauts will cross over to enter the Orion spacecraft atop the SLS. The arm is hinged where it connects to the tower and can be swung around to join with the Orion spacecraft for astronaut access and then be swung out of the way, as seen here, when the rocket launches.

Launch Pad 39B at Kennedy Space Center being built to support the launch of the SLS rocket for missions to the Moon and Mars. Pad subsystems used for Apollo and the Space Shuttle Program were replaced or upgraded to support the SLS and 21st century multi-user spaceport.

The guiding principle behind the upgrades and modifications made the area a “clean pad,” which will allow a variety of companies to launch their rockets from the pad. The basics that every rocket needs will remain in place, such as electrical power, a water system, flame trench and safe launch area. The other needs of individual rockets, including access for workers, can be met with the towers or other structures that deliver the rocket to the pad.

Refections of the VAB and mobile launcher in the gathering dusk.

Click to view SLS ML at 39B – Part Two

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