When Building the World's Largest Rockets, Construction Starts With the Tools Themselves

In a facility in New Orleans, NASA scientists are facing an unusual problem: what do you use when a hammer and nail just aren't big enough to construct the world's largest rocket?

In response to that question, engineers at the Michoud Assembly Facility are installing massive tools -- one more than 170 feet tall -- specifically designed and built to weld together pieces of the Space Launch System, NASA's heavy-lift rocket for blasting humans into deep space destinations such as asteroids and Mars.

Once complete, the system will weigh some 5.5 million pounds and measure 321 feet long.

"One of the challenges that we face in building this large core stage is to develop world-class tooling using modern manufacturing methods in an affordable way, while maintaining the scheduled first launch in 2017," Tony Lavoie, manager of the Stages Office at NASA's Marshall Space Flight Center in Huntsville, Ala., said in a press release. "This tool set that we've developed for Michoud to build the core stage is a perfect blend of those requirements and constraints."

In all, six main welding tools will be used to handle the assembly of the new cryogenic core stage on the SLS that suppliers working with NASA and The Boeing Company have worked over the last year to design and build.

The Circumferential Dome Weld tool, for example, will be used to perform circumferential friction stir welds in the production of dome assemblies for the SLS core stage cryogenic tanks. Meanwhile, the Gore Weld tool will perform vertical conventional friction stir welds in the production of gore assemblies for the SLS core stage tanks. Both, the Circumferential Dome Weld and Gore Weld tools, are special tooling for the Enhanced Robotic Weld Tool used to make dome components for the SLS.

The Vertical Weld Center is a friction-stir-weld tool for wet and dry structures on the SLS core stage that will weld barrel panels together to produce whole barrels for the two pressurized tanks, the Intertank, the Forward Skirt and the Aft Engine Section. In all, it stands about three stories tall and weighs 150 tons.

The Segmented Ring Tool will use a friction-stir-weld process to produce segmented support rings for the SLS core stage that will connect and provide stiffness between domes and barrels.

And finally, the Vertical Assembly Center (VAC) is where domes, rings and barrels will be joined together to complete the tanks or dry structure assemblies. The tool also be used to evaluate the completed welds. Measuring 170 feet tall and 78 feet wide, the VAC will be one of the world's largest welding tools when completed in 2014.

"It's an exciting time to be a part of NASA's team," said Rick Navarro, Boeing operations manager at Michoud. "We're already welding on the new tooling and are gathering information we'll need to start production welding. That old saying, 'measure twice, cut once,' applies in spades when you're building a 5.5 million-pound rocket. We do a lot of testing, validating and what we call 'qualifying' welds that ensure we have all the information we need to build with 100 percent quality assurance."

However, despite all the construction going on, the rocket also will use proven hardware from other programs like the space shuttle, which means major cost savings, according to those behind the project.

"We are one step closer to building the first core stage in what will hopefully be a long line of rockets to support future NASA missions," Lavoie said.