A crane moves the first steel tier to be bolted into place on Jan. 6, for welding of a second new structural test stand at NASA's Marshall Space Flight Center in Huntsville, Alabama - critical to development of NASA's Space Launch System.

When completed this summer, the 85-foot-tall Test Stand 4697 will use hydraulic cylinders to subject the liquid oxygen tank and hardware of the massive SLS core stage to the same loads and stresses it will endure during a launch.

The stand is rising in Marshall's West Test Area, where work is also underway on the 215-foot-tall towers of Test Stand 4693, which will conduct similar structural tests on the SLS core stage's liquid hydrogen tank.

SLS, the most powerful rocket ever built, will carry astronauts in NASA's Orion spacecraft on deep space missions, including the journey to Mars.