Using a metal joining technique called friction stir welding, the Ares Projects team at the Marshall Center has completed welding the first liquid hydrogen tank dome being developed to define manufacturing processes for the upper stage of the Ares I -- the rocket that will launch explorers to the moon, Mars and beyond in coming decades. The innovative welding process produces high-strength welds that are uniformly joined together -- a vital requirement for next-generation launch vehicles and hardware designed for long-term space travel.
The completed dome is the first development hardware assembled for the Ares I upper stage.
"Our team is working to implement new techniques and processes that will make the Ares vehicle one of the safest, most technologically advanced spacecraft ever flown," said Danny Davis, manager for the Ares I Upper Stage Element Office. "The completion of this first demonstration dome represents a milestone in our continuing development of the Ares I upper stage."
The hydrogen dome assembly took place at the Marshall Center's Weld Development Facility, home to two new full-scale welding tools. The robotic weld tool and the vertical weld tool are the largest, most sophisticated and versatile tools of their kind.Previously, friction stir welding has been limited to use on straight linear welds, such as the longitudinal seam welds joining barrel panels on the space shuttle external tank. The new vertical tool will continue to provide this capability, but can accommodate much larger Ares V-sized hardware. With the new robotic weld tool, engineers will be able to perform friction stir welds on more complex shapes and angles, including tanks and other structures with complex curvature. On the Ares I upper stage, all the major structural welds, including welds on the difficult angles required for bulkhead assembly and the rocket’s large metallic structures, will be performed using friction stir welding.
Also, given the ability of these new tools to more adeptly weld lightweight materials, they’re helping NASA engineers reduce the weight of spacecraft. This savings, in turn, lowers launch costs.
"Every aspect of the manufacturing process required to build the Ares is new, including the welding tools, the welding fixtures needed to hold our components and subassemblies, and the welding processes itself," said Tim Vaughn, chief of the Marshall Center's Metals Engineering Branch.
With the completion of the hydrogen dome, engineers now will begin manufacturing the common bulkhead, used to join the liquid hydrogen and liquid oxygen tanks. This step in the manufacturing development process is expected to take one year and will be followed by barrel, or side panel, assembly.
"We have gone back to the von Braun model for hardware development. NASA owns the design and development process; the contractor owns the production manufacturing process," said Vaughn. "We are writing the playbook on how to manufacture the upper stage as we go. This information is being documented and will be transferred to The Boeing Company, the prime contractor for the Ares I upper stage, for final production. The things we have learned while building this hydrogen dome represent the first chapter in that book."Using NASA's design for the Ares I upper stage, Boeing will be responsible for production of the stage. Under a contract awarded in August 2007, Boeing will manufacture a ground test article, three flight test units and six production flight units to support Ares I flights through 2016. Final assembly of the upper stage will take place at NASA's Michoud Assembly Facility in New Orleans, using friction stir welders similar to those at Marshall.
NASA's Johnson Space Center in Houston manages NASA's Constellation Program, which includes development of the Ares I rocket. The Marshall Center manages the Ares Projects for the agency.
For more information about Ares, visit:
http://www.nasa.gov/ares
For more information about NASA programs, visit:
http://www.nasa.gov/home
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