Spaceflight Insider

NASA celebrates 57 years as new SLS heavy-lift booster completes CDR

In the same week that the space agency celebrated its 57th anniversary, NASA announced that its new super heavy-lift booster had completed its Critical Design Review (CDR). The Space Launch System or “SLS” is the booster that NASA plans to use for crewed missions into deep space. With the agency in a transition period between crewed programs, reviews such as this one are critical to ensure that the new rocket is ready to launch as early as 2018.

The website ECN noted that the 11-week analysis of the new launch vehicle had been completed at NASA’s Marshall Space Flight Center (MSFC) located in Huntsville, Alabama.

According to NASA, this is the first time that such scrutiny has been given to an exploration class vehicle in nearly 40 years. CDR’s are held to provide a comprehensive evaluation of the rocket’s current state of development. The next step in the launch vehicle’s life will be full-scale fabrication.

“Now that we’ve completed our review, we will brief NASA leadership, along with the independent review team, about the results and readiness to proceed to the next phase. After that step is complete, we’ll move on to design certification,” said Todd May, NASA’s SLS program manager. “Critical design review represents a major commitment by the agency to human exploration, and through these reviews, we ensure the SLS design is on track to being a safe, sustainable and evolvable launch vehicle that will meet the agency’s goals and missions.”

Over the course of about two-and-a-half months, some 13 teams who hailed from various NASA centers, scoured more than 1,000 files produced as SLS has been developed. The preponderance of documents examined during the CDR was provided by NASA’s Engineering Directorate at MSFC.

According to NASA, to date, SLS’ boosters, engines, and core stage have already had their CDR’s completed with both the integrated spacecraft and the payloads that will fly on SLS almost finished. In short, efforts to get the booster to fly appear to be moving ahead according to schedule.

Blueprint of NASA's Space Launch System SLS NASA image posted on SpaceFlight Insider

With the CDR now complete, its findings will be reviewed by the Standing Review Board. Image Credit: NASA

“We’ve nailed our review schedules,” said Garry Lyles, chief engineer for the SLS Program Office. “The team is performing at a really high level. And I’m unbelievably positive in the structural robustness of this vehicle; it has tremendous performance. We’ve picked the right vehicle for the journey to Mars.”

This CDR only encompasses the first three SLS that are currently slated to fly. Known as the Block 1 version, the booster will stand some 322 feet (98 meters) in height. If predictions are accurate, when launched, the rocket will have the capability of unleashing some 8.4 million pounds of thrust at liftoff. The first versions of SLS that will take to the skies will be able to carry 154,000 lbs (69,853 kg; 70 metric tons) to orbit.

At present, the massive new launch vehicle is scheduled to launch in 2018 on what has been dubbed Exploration Mission 1 (EM-1). During this cislunar flight, an uncrewed spacecraft will fly to demonstrate that both NASA’s new crew-rated Orion spacecraft and SLS can function as one.

Marshall is not alone in having to complete CDRs to validate that the ground support and spacecraft systems are able to support sending crewed missions to distant destinations throughout the solar system. Johnson and Kennedy Space Centers also have to complete the review of all elements that will be used on this new vehicle.

Although listed as a “NASA” effort, the space agency is not producing this rocket on their own. The agency will rely on experienced contractors such as Boeing, Lockheed Martin, Aerojet Rocketdyne, and Orbital ATK. These firms will produce the core stage of the rocket, the Orion spacecraft, the RS-25 engines in the initial versions of SLS and the two five-segment solid rocket boosters that are attached to each rocket, respectively.

NASA Space Launch System SLS Orbital ATK five segment booster NASA image posted on SpaceFlight Insider

An array of contractors are involved in producing the SLS booster. This image shows the five-segment solid rocket boosters that will be used on initial flights of the rocket. Image Credit: NASA

Fueled by a mix of liquid hydrogen and liquid oxygen, the core stage alone stands 200 feet (61 meters) in height and is 27.6 feet 8 meters) in diameter and employs four RS-25 engines to help it aloft.

Upon completion, the CDR was submitted to the Standing Review Board. Comprised of aerospace experts from within and outside the space agency, they reviewed the program’s state of readiness. NASA has stated that the Standing Review Board worked to certify that SLS was indeed ready to meet schedule and budgetary requirements.

“Much of the benefit of this review is what we do to prepare for it because that’s where we really bring things out,” said Jim Reuter, head of the Standing Review Board. “And you can tell it in the spirit of the people here. They are excited about what they’re doing. They can see that this is the review that’s going to make it real.”

As with all efforts of this scale, a number of steps, procedures, and approvals have to be met before the rocket can be launched without astronauts – let alone with a crew on board Orion perched atop.

The Orion spacecraft also continues to undergo testing with the vehicle’s prime contractor, Lockheed Martin, recently carrying out tests to ensure that everything will work as advertised when it carries crews to orbit – and beyond. Two tests to demonstrate changes made to the vehicle’s fairing were carried out in June and July of this year to validate modifications that had been made to the design.

Video courtesy of Lockheed Martin

“A thorough review requires a wide range of engineering skills and experts to assess everything from avionics and software that fly the vehicle to ground transportation and integrated systems testing designs and plans,” said Preston Jones, deputy director of Marshall’s Engineering Directorate. “We have gone through every design interface and rechecked analysis to ensure we are meeting all SLS mission performance and crew safety requirements.”

NASA is hoping to send a crew to part of an asteroid that has been towed into lunar orbit some time in the 2020s. If that mission takes place, the agency will begin working on a far loftier goal – sending astronauts to Mars.

NASA was founded on July 29, 1958 by President Dwight D. Eisenhower. Formed, in part, as a response to the Soviet launch of Sputnik 1 in October of 1957, the agency would go on to send men to the Moon, spacecraft to all of the classical planets and much more.

“It’s an exciting time for NASA and our nation,” May continued, “as we prepare to go to places in deep space that we’ve never been before,” May said.

NASA Cassini spacecraft image of Saturn's moon Europa. NASA photo posted on SpaceFlight Insider

SLS has been mentioned for use in sending a mission to Jupiter’s moon Europa. Image Credit: NASA


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

Yes but what is it going to do? So far there is not one single mission with funding for hardware for this vehicle. Given the timeframes to build any significant hardware these days together with the cost of such hardware, it looks like it here will be a significant gap of many years before any mission for SLS is actually ready to fly. IIRC, NASA has stated that they need to fly at least once a year to fly safely. Guess that means maintaining a technical capability.
So many questions on this issue and so few answers.

“So many questions on this issue and so few answers.”

The answers are;

First the ISS is going out of business sooner than anyone is thinking it will because costs are soon going to “skyrocket” due to maintenance. It will never last till 2024 because that would cost several more billion than can be justified and will likely be abandoned before the end of the decade.

Second is Luna has become the next place to go because of international interest and the slow realization that Mars is not going to happen. The fantasies of Bigelow space hotels are effectively dead since after years of soliciting there are no investors stupid enough to spend a nickel on a project that cannot turn a profit.

Third is that beyond earth orbit is the place the commercial space enthusiasts unconsciously understand is beyond their reach and for this reason they must act out their state of denial and always ask rhetorical questions like, “what is it going to do”?

Hi Gary. Nope, you haven’t answered any of my questions. ISS is now being supported to 2024 by the Russians and still no funding for anything SLS might fly. The basic op’s funding isn’t estimated at this point or approved, only development and one test flight.

Congratulations to NASA, especially Todd May, and its partners at Boeing, Orbital ATK, Lockheed Martin and Aerojet Rocketdyne. On to Mars and on to Europa!

SLS/Orion= The 2015 version of an enhanced Saturn 5 Rocket with an enhanced Apollo command module. It’s meant to be a symbol of American leadership in space. It’s the national government launch system. It’s not meant to be cost effective or launch on a regular basis. When other countries look at the U.S. space assets, they will see the ability to launch man & machine to any point in BEO. Not cost effective launches, but, high dollar cost-plus government launches. The others, commercial crew/cargo & suborbital providers are meant to be the work horses of LEO & eventually BEO. Just my opinion.

⚠ Commenting Rules

Post Comment

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