Welders inside a large liquid hydrogen tank being manufactured for NASA’s Space Launch System at the Michoud Assembly Facility in New Orleans are using advanced fusion welds to plug holes left after the tank was assembled. The Space Launch System, the nation’s next heavy-lift rocket, is managed for the agency by NASA’s Marshall Space Flight Center in Huntsville, Alabama. The liquid hydrogen tank, a liquid oxygen tank, four RS-25 engines and other elements form SLS’s core stage, which also serves as the rocket’s structural backbone. Carrying NASA’s crewed Orion spacecraft, SLS — the most powerful rocket in the world — will send astronauts deeper into space than ever before, and serve as the key vehicle for NASA’s journey to Mars. (NASA/Michoud/Steve Seipel)