NASA’s Space Launch System (SLS) Program and prime contractor Boeing have a new framework in place to finish development of the next version of the new launch vehicle, called Block 1B. The biggest addition to the Block 1B SLS vehicle will be the Exploration Upper Stage (EUS), which completed its Critical Design Review (CDR) on December 18.
The CDR milestone indicates the design of the larger, higher performance upper stage is mature enough to begin construction and assembly of the test and flight articles needed for first flight certification while incorporating lessons learned while starting Core Stage production, including the 2020 creation of a separate Block 1B/EUS Development Office within the program to advance Block 1B to its first flight while much of the rest of the workforce focuses on efforts to get the initial SLS Block 1 vehicle off the ground for the first time on Artemis 1.