Boeing has completed its first major technical reviews for the cryogenic stages of the Space Launch System (SLS), bringing the team into the design phase for the nation's next heavy-lift, human-rated rocket.

The combined System Requirements Review (SRR) and System Definition Review (SDR), held at NASA's Marshall Space Flight Center in Huntsville with independent consultants from previous successful programs, validated that Boeing and NASA have developed solid system requirements for the cryogenic stages and supporting hardware. A cryogenic rocket engine uses liquefied gas stored at very low temperatures for optimal rocket efficiency.

While SRR is a contractual requirement, Boeing simultaneously pursued the SDR to enable a higher quality of requirements as the team enters the design phase. The reviews, completed well ahead of the scheduled August time frame for SRR, enabled a more aggressive path to core stage delivery to NASA, and validated the stage's design concept and production approaches.

NASA's plan uses existing elements for the boosters, crew capsule, and engines, but the cryogenic stages are new elements that require significantly more design and development. That makes successful, timely reviews essential to the progress of the entire SLS program.

"The Boeing and NASA team is demonstrating the value of our integrated approach to developing requirements," said Jim Chilton, vice president and program manager for Boeing Exploration Launch Systems.

"SRR locks in requirements and serves as the basis for our estimates and performance metrics," said Chuck Hanes, Boeing SLS business manager. "The understanding we reach at SRR and SDR is a firm commitment to the rocket's requirements, design and resources."

Boeing is designing, developing and producing part of SLS, the United States' next-generation, human-rated rocket to transport people to deep space, enabling the next step in space exploration. Boeing is responsible for the SLS cryogenic stages and avionics. Design work for the cryogenic stages is performed in Huntsville, with production at NASA's Michoud Assembly Facility in New Orleans.