Spaceflight Insider

NASA’s SLS completes Critical Design Review and gains flashy new colors

NASA Space Launch System SLS Orion Marshall Space Flight Center Boeing Orbital ATK Lockheed Martin NASA photo posted on SpaceFlight Insider

NASA’s Space Launch System booster at Kennedy Space Center’s Launch Complex 39B in Florida. Image Credit: NASA

NASA recently unveiled the overall strategy for the space agency’s effort to send crews to the planet Mars. On Thursday, Oct. 22, NASA announced that the rocket the agency is planning to use to enable this journey to begin has now completed a major milestone on the road to flight.

The booster, NASA’s Space Launch System or “SLS“, completed a Critical Design Review, which covered the entire launch vehicle. According to NASA, this is the first crew-rated booster to achieve this feat in almost 40 years.

NASA Space Launch System SLS Orion Marshall Space Flight Center Boeing Orbital ATK Lockheed Martin NASA photo posted on SpaceFlight Insider

NASA hopes to conduct the first uncrewed flight of SLS as early as 2018. Image Credit: NASA

“We’ve nailed down the design of SLS, we’ve successfully completed the first round of testing of the rocket’s engines and boosters, and all the major components for the first flight are now in production,” said Bill Hill, deputy associate administrator of NASA’s Exploration Systems Development Division. “There have been challenges, and there will be more ahead, but this review gives us confidence that we are on the right track for the first flight of SLS and using it to extend permanent human presence into deep space.”

NASA hopes that, like the Saturn V launch vehicle used by the Apollo astronauts to reach the Moon, the SLS will allow the agency to regain the ability to send crews to destinations that, at present, include a portion of an asteroid towed into lunar orbit and, perhaps, Mars.

“This is a major step in the design and readiness of SLS,” said John Honeycutt, SLS’ newly-appointed program manager. “Our team has worked extremely hard, and we are moving forward with building this rocket. We are qualifying hardware, building structural test articles, and making real progress.”

The agency has described the rocket as “[…] the most powerful rocket ever built.” It is being developed to send NASA’s Orion spacecraft and other payloads targeted for exploration missions to low-Earth orbit (LEO).

In terms of the CDR, NASA reviewed the design and development of the booster and its various components to make sure that the rocket was ready for full-scale fabrication.

The Block 1 configuration of SLS was checked out through this CDR to ensure that the booster has a lift capability of some 70-metric-tons (77-tons). This first of three planned versions of the rocket will also utilize two five-segment solid rocket boosters provided by Orbital ATK and four Aerojet Rocketdyne RS-25 rocket engines.

From there, SLS should undergo a planned upgrade to the SLS, Block 1B configuration. This version of the rocket will have a more powerful exploration upper stage for potential future missions. The Block 1B version of the booster should have the ability to hoist 105-metric-ton (115-ton) payloads to LEO.

During this point in the booster’s evolution, the Space Launch System will have had a pair of advanced solid or possibly liquid propellant boosters replace the initial SRBs attached to the rocket’s core stage. These new boosters will help the heavy-lift launch system evolve into the third envisioned configuration of the rocket – one that should have a 130-metric-ton (143-ton) lifting capacity.

Through all three planned versions of the rocket, the same core stage and four RS-25 engines will be employed.

Along with a separate review that was carried out by the Standing Review Board, the SLS Program completed the CDR this past July.

The Standing Review Board is composed of individuals from within and outside of NASA. All of the board members are not involved with the SLS Program.

Space Launch System at a Glance infographic NASA image posted on SpaceFlight Insider

SLS graphic. (Click to enlarge.) Image Credit: NASA

The CDR took place over a course of about 11 weeks. During that time, 13 teams, which included senior engineers and aerospace experts across the agency and from industry, went over more than 1,000 documents that pertained to the program. That included more than 150 GB of data. The review took place at NASA’s Marshall Space Flight Center, located in Huntsville, Alabama.

Through a release issued by NASA, the agency has stated that the Standing Review Board reviewed SLS’ programs’ overall state and that the total system is on track and on budget.

The results were presented to NASA Associate Administrator Robert Lightfoot this month (October 2015). Lightfoot is in charge of the Agency Program Management Council. That marked the last phase of the CDR process.

SLS has to undergo four reviews to check and validate the system’s overall design – the CDR is the last of these reviews before the rocket moves on to Design Certification. Design Certification will take place after SLS’ manufacturing, integration, and testing are finished – currently slated to take place in 2017. Essentially, Design Certification will look at how closely the actual booster resembles the initial design.

If everything continues to go according to schedule, in 2018 SLS will undergo its flight readiness review in preparation for Exploration Mission 1 – the first, uncrewed, flight of SLS.

Critical Design Reviews have been carried out for SLS’ core stage, its SRBs, and the RS-25 rocket engines were all carried out successfully – before this overall CDR could be completed.

On an interesting aesthetic note, as highlighted in an article on, the early renders of SLS depicted the rocket looking very similar to the Saturn V. However, this apparently is no longer what the rocket will actually look like. Rather, it will have an orange core stage due to the insulation foam used on this part of the rocket (likely similar to the external tank on NASA’s now-retired space shuttles and United Launch Alliance’s Delta IV family of launch vehicles).

Noting its role as a super heavy-lift booster, the SLS will be massive. Its core stage alone will measure 200 feet (61 meters) in height and some 27.6 feet (8 meters) in diameter. Its four RS-25 engines will be supplied with a mixture of cryogenic liquid hydrogen fuel and liquid oxygen oxidizer. The RS-25s, which are, for the most part, leftover Space Shuttle Main Engines, will be used differently (as will the SRBs) than they were during the Shuttle era in that they won’t be reused.

With the CDR now complete, both SLS, the Orion spacecraft, and other payloads it will carry aloft are nearing completion and integration. NASA and Orbital ATK are preparing to conduct the second Qualification Motor test of the initial SRBs. Perhaps most notably in terms of the rocket’s progress, NASA has stated that “[…] the core and upper stages of the rocket are either completed or are currently in production.”

Video courtesy NASA’s Marshall Space Flight Center


Jason Rhian spent several years honing his skills with internships at NASA, the National Space Society and other organizations. He has provided content for outlets such as: Aviation Week & Space Technology,, The Mars Society and Universe Today.

Reader Comments

Good article

⚠ Commenting Rules

Post Comment

Your email address will not be published. Required fields are marked *