Mobile launcher 1 is the ground structure that is used to assemble, process, and launch NASA’s Space Launch System (SLS) rocket and Orion spacecraft from Launch Pad 39B at the agency’s Kennedy Space Center in Florida for missions to deep space destinations, such as the Moon, Mars, and beyond. 

During preparations for launch, the crawler-transporter picks up and moves the mobile launcher into High Bay 3 in the Vehicle Assembly Building. The launcher is secured atop support posts and the crawler moves out. The Orion spacecraft is stacked atop the SLS rocket and processed on the mobile launcher. 

The mobile launcher consists of a two-story base that is the platform for the rocket and a tower equipped with a number of connection lines, called umbilicals, and launch accessories that provide SLS and Orion with power, communications, coolant, fuel, and stabilization prior to launch. The tower also contains a walkway for personnel and equipment entering the crew module during launch preparations. 

The launcher rolls out to the pad for launch on top of the crawler-transporter, carrying SLS and Orion. After the crawler-transporter makes its eight-hour trek to the pad just over four miles away, engineers lower the launcher onto the pad and remove the crawler-transporter. During launch, each umbilical and launch accessory releases from its connection point, allowing the rocket and spacecraft to lift off safely from the launch pad. 

Fun Facts:

• Total height above ground: 380 feet
• Tower: 40 feet square, about 355 feet tall, 662 steps
• Tower floor levels: every 20 feet for personnel access to vehicle and ground support equipment
• Approximate weight: 11.5 million pounds