Essentially, the Space Launch System is just the Space Shuttle, but with the airplane-like orbiter deleted, allowing its mass to be replaced by an upper stage a

Essentially, the Space Launch System is just the Space Shuttle, but with the airplane-like orbiter deleted, allowing its mass to be replaced by an upper stage and/or a greatly increased payload. Such a simple variant on the Shuttle should have been flying by the mid-90s, and had it been, we could have seen it serve as an enabling technology for a much more capable space program for the past quarter century.