In other words it's still entirely on paper, but now they will be taking a closer look at the paper.
On July 25th, it hit a major milestone when it was officially upgraded by an independent review board from the “concept development“ phase of the project to the “preliminary design“ phase.
“The in-depth assessment confirm the basic vehicle concepts of the SLS, allowing the team to move forward and start more detailed engineering design.“ William Gerstenmaier of NASA’s Human Exploration and Operations Mission Directorate said. This puts the system on the path to the next milestone: the preliminary design review expected late next year.
STARGAZING: All I see are the lights of a billion places I'll never go. --Howard Tayler, Schlock Mercenary