NASA’s Space Launch System: Specs, Size, History, and More

NASA emblem at the Kennedy Space Center Visitor Complex

NASA’s Space Launch System: Specs, Size, History, and More

Key Points

  • NASA does not build its own launch vehicles.
  • When NASA needs propulsion technology, they typically contract Aerojet Rocketdyne.
  • Boeing is also responsible for several components connected to NASA launches.

NASA formally announced the Artemis program in 2017, with the aim of sending humans back to the moon. Private companies such as SpaceX and Blue Origin went to work designing rockets that could support the program, but NASA would build a rocket of its own.

With contracted help from the country’s most prominent defense contractors, NASA would design a rocket that would outclass even the historic Saturn V. The Space Launch System is the biggest and most powerful rocket the organization has ever had. Continue reading for everything you need to know about the latest space launch vehicle.

Quick Facts

Year Founded
Dwight D. Eisenhower
aeronautics, space research, exploration
Washington, D.C
Key People
Steve Jurczyk, Bill Nelson
Notable Products
Space Shuttle, Hubble Space Telescope, James Web Telescope

Does NASA Build Their Own Rockets?

The simple and straight answer is, NASA does not build its own launch vehicles. For everything from the Delta family of rockets to the iconic Saturn V, the government space agency hires contractors. The Space Launch System (SLS) is included, and for that, NASA hired several companies to build different components.

Aerojet Rocketdyne


A rocket must obtain thrust from a rocket engine in order to launch.

When NASA needs propulsion technology, they typically contract Aerojet Rocketdyne. The company built the J-2 and HG-3 engines that were used in the Saturn family of rockets during the Apollo era. Now, as NASA prepares for the Artemis era, the defense contractor returns with modified RS-25 rocket engines. SLS comes equipped with 4 of them, each producing over 400,000 pounds of force.

Northrop Grumman

The SLS will use two five-segment solid rocket boosters, some of which are remnants from the Space Shuttle program canceled in 2011. To maintain these old SRBs, NASA hired Northrop Grumman Space Systems.

The company regularly runs static fire tests to confirm its usability. When the old SRBs run out, the defense contractor will start building new ones. These SRBs produce most of the Space Launch System’s propulsion, with each producing 3.3 million pounds of thrust.


Responsible for several components, Boeing is the primary contractor for the SLS. The defense contractor is building the rocket’s core stage, which provides most of the vehicle’s propulsion beyond Earth’s atmosphere. The core stage stands 213 feet tall, making it the largest core stage in history (excluding Starship). 

In addition, Boeing is constructing the upper stages for each SLS variant. The Interim Cryogenic Propulsion Stage (ICPS), which uses Delta-inspired launch technology, will launch with the first three Artemis missions. Upcoming missions to the moon will launch with the Exploration Upper Stage (EUS), which has four times the propulsion as its predecessor.

The EUS will have the capacity to carry considerable payloads, such as habitation modules, to the moon’s surface and beyond.

What Is the Space Launch System?

Engine section of the space launch system
SLS will have four RS-25 engines, two massive propulsion tanks, and advanced avionics.

The SLS is NASA’s newest super-heavy launch vehicle. Replacing the older Ares rockets from the canceled Constellation program, the SLS aims to return humans to the moon.

With several US defense contractors having hands on the project, NASA plans on upgrading the launch vehicle in variants as needed to progress through the Artemis program.

Block 1

While the extent of the Artemis program entails missions into deep space, the SLS Block 1 is built to test the feasibility of returning to the moon. The variant features a stage adapter that allows for the ICPS to attach. The first-phase design stands up to 322 feet tall and has a payload capacity to the moon of 59,500 pounds.

Block 1B

Following the first few missions of the Artemis program, NASA will introduce adaptable launch technology to send payloads beyond the moon. SLS Block 1B swaps out the ICPS for the EUS, which has four times the thrust as the former upper stage.

To protect its four RL10C-3 engines, engineers will attach an interstage. The EUS shares the same diameter as the core stage, so a universal stage adapter allows for the Orion spacecraft to connect. With all these extra parts, the SLS Block 1B measures up to 365 feet and can haul payloads to the moon as heavy as 92,500 pounds.  

Block 2

With the EUS successfully tested, NASA will upgrade thrust to carry habitation modules to lunar orbit. Block 2 introduces new SRBs from the Booster Obsolescence and Life Extension program. The EUS will also feature improved engines, allowing it to carry a larger cargo fairing. The improvements give the SLS a payload capacity of nearly 300,000 pounds to lower Earth orbit (LEO) and 101,000 pounds to trans-lunar injection.

Space Launch System Specs

HeightBlock 1 crew: 322 feetBlock 2 cargo: 365 feet
Total weight5.75 million pounds
Diameter27.6 feet
PayloadBlock 1: 95-105 tonsBlock 2: 130 tons
Engine count4
Propellant capacity730,000 gallons
Thrust8.8 million pounds
Launch dateAugust 29 (rescheduled)

What’s Next for the Space Launch System?

With its construction complete, SLS is scheduled to carry out its first mission as early as mid-November 2022. Here’s how NASA plans to use its different variants for lunar exploration.

Artemis 1-3

artistic impression of the space launch system
Artemis program by NASA seeks to re-establish human presence in the moon with Artemis 1 set to launch on 14 November 2022.

The first three missions of the Artemis program sets the groundwork for astronauts to return to the moon. Artemis I is an unmanned mission that tests SLS Block 1, sending the Orion spacecraft into a distant lunar orbit. 

With the vehicle updated for human travel, the second mission sends astronauts on a similar trajectory. SLS will launch Orion into a free-return trajectory around the moon before returning the crew back to earth.

The third mission sends Orion to rendezvous with a human landing system in a near-rectilinear halo orbit. The crew will descend to the moon and spend about a week on the surface before returning to Orion.

Artemis 4-8 and Beyond

The second round of Artemis missions is set to span the length of time astronauts spend in lunar space. Artemis IV uses SLS Block 1B to send the I-HAB gateway module to the Lunar Gateway (built during support missions). The Gateway allows astronauts to spend 30 days or more in a research facility with easier access to the moon’s surface. 

As missions progress, astronauts will take advantage of more infrastructure. NASA will upgrade to the SLS Block 2 to handle payloads used to add larger modules.

Space Launch System: Further Reading

With the Artemis program only weeks from launch, there’s never been a better time to follow the progress of the Space Launch System. NASA’s largest rocket isn’t the only vehicle working to make it to the moon, however. For the latest in space and exploration, check out the articles below.

Frequently Asked Questions

When was the Space Launch System created?

Following the cancellation of the Space Shuttle program in 2011, NASA started developing the Space Launch System. The rocket was contracted to possibly send humans back to space in a more reliable fashion.

Is the SLS more powerful than Saturn V?

The SLS will produce nearly 8.8 million pounds of thrust, roughly 15 percent more than Saturn V.

Is Starship more powerful than SLS?

With state-of-the-art methalox rocket systems, SpaceX’s Starship rocket is estimated to generate around 17 million pounds of thrust, nearly twice that of the SLS.

How many engines does SLS have?

The Space Launch System comes equipped with four RS-25 rocket engines, each producing 400,000 pounds of thrust. The rocket also comes with two solid rocket boosters, producing 3.3 million pounds of thrust each.

Is the Space Launch System reusable?

The Space Launch System is entirely expendable, meaning all of its components are either destroyed upon return or expelled into deep space.

To top