National Aeronautics and Space Administration

www.nasa.gov #Artemis Version 2

REFERENCE GUIDE

SYSTEM

SPACE LAUNCH

NASA's

TABLE OF CONTENTS

Table of Contents

From the SLS Program Manager and Chief Engineer. 

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  

SLS Quick Facts  

NASA’s Block 1 Space Launch System by the Numbers. 

 SLS Vehicle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

 Core Stage. 

 RS-25 Engines. 

 Solid Rocket Boosters. 

 Interim Cryogenic Propulsion Stage (Upper Stage). 

 Launch Vehicle Stage Adapter. 

 Orion Stage Adapter. 

 Secondary payloads. .

SLS Overview. .

SLS Design: Chosen from Thousands of Options. .

Common Elements and Evolvability. .

 More Powerful Rockets for Future Missions. .

SLS Vehicle-Level Testing. .

Super Heavy Lifting on the Ground: SLS Transportation, Logistics, and Pathfinders. .

Exterior Features of SLS. .

 Thermal Protection System. .

 Livery and Photogrammetric Markings. .

 Instrumentation and Vehicle Telemetry. .

The Role of SLS in Launching Artemis I. .

Artemis I Secondary Payloads. .

The Elements of SLS. .

Core Stage. .

 Manufacturing, Test, and Checkout. .

 Core Stage Fun Facts. . 

3
CONTINUED TABLE OF CONTENTS

RS-25 Engines. .

 Manufacturing, Test, and Checkout. .

 Flight History of Artemis I RS-25 Engines. .

 RS-25 Fun Facts. .

Solid Rocket Boosters. .

 Manufacturing, Test, and Checkout. .

 Flight History of the SLS Booster Structures. .

 Solid Rocket Boosters Fun Facts. .

Integrated Spacecraft/Payload Element. .

 Interim Cryogenic Propulsion Stage. .

 Launch Vehicle Stage Adapter. .

 Orion Stage Adapter. .

 Manufacturing, Test, and Checkout. .

SLS Avionics and Software. .

Management Roles and Facilities. .

Marshall Space Flight Center. .

 Unique Test Facilities. .

 Supporting Launch Operations. .

Michoud Assembly Facility. .

Stennis Space Center. .

Industry Partners. .

Aerojet Rocketdyne. .

Boeing. .

Northrop Grumman. .

Teledyne Brown Engineering. .

United Launch Alliance. .

Additional Resources. .

Understanding SLS: Infographics. .

Acronym List. .

4
FROM THE SLS PROGRAM MANAGER AND 

CHIEF ENGINEER

From the SLS Program Manager and 

Chief Engineer

5

As Program Manager and Chief Engineer for NASA’s Space 

Launch System (SLS), it has been our honor to shepherd 

America’s new super heavy-lift rocket – a launch vehicle 

like no other – from design, through testing, manufacturing, 

assembly, and now launch of the Artemis I test flight. We’d 

like to thank our team members, stakeholders, and industry 

partners in this endeavor. This is America’s rocket, and we 

could not have made it to the launch pad without you.

After the Apollo Program ended, NASA focused on learning 

to live and work in low-Earth orbit – about 250 miles up – 

with the space shuttle and the International Space Station 

(ISS). There have been astronauts living continuously 

onboard the ISS since 2000, and our knowledge of how to 

keep crew safe, conduct science, and maintain living and 

laboratory facilities in space has advanced tremendously. 

Now, NASA’s human spaceflight program is once again 

looking to deep space...to the Moon and then to Mars.

And for that, a new rocket, new spacecraft for crew, and 

new ground and launch capabilities are needed.

Meet the Space Launch System rocket, the Orion crew 

spacecraft, and Exploration Ground Systems (EGS) 

at NASA's Kennedy Space Center in Florida. These 

technologies are making a new generation of missions to 

the Moon – the Artemis Generation – possible. Along with 

the Gateway and the Human Landing System, NASA is 

preparing to send more astronauts, conduct more science, 

and explore more of the Moon than ever before.

SLS is the rocket that will launch Orion and its crew to lunar 

orbit. While the initial configuration, the Block 1 rocket for 

Artemis I, will launch with 8.8 million lbs. of thrust (more 

than even the Saturn V), future variants will be even more 

powerful. Sending astronauts to the Moon 239,000 miles 

away – one thousand times farther than the space station 

in low-Earth orbit – is an inherently risky and dangerous 

undertaking. 

We are proud of the extensive testing, from component to 

entire vehicle, that has gone into making SLS the safest, 

most reliable rocket for human missions that NASA has ever 

built. And the Artemis I test flight gives us a chance to test 

out all the systems in deep space, as well as our procedures 

on the ground, before we take the next giant leap and once 

again send astronauts to the Moon.

So, why build SLS? So the world can see a new generation 

of bootprints in lunar regolith. To advance from a 

20th-century Moon shot to a 21st-century Moon stay. To 

build, with our partners, not just a rocket, but a platform 

for human missions to the Moon and science missions to 

explore the solar system, like those of us staring at the stars 

and heavens have always dreamed of. Why build SLS? To 

find out not only what’s out there but what’s in us.

John Honeycutt

SLS Program Manager

Dr. John Blevins

SLS Chief Engineer
This document was prepared by NASA’s SLS Program 

Office at NASA’s Marshall Space Flight Center, in Huntsville, 

Alabama, which has responsibility for design, development, 

testing, and engineering of SLS, the new super heavy-lift 

rocket that will send astronauts to the Moon as part of the 

Artemis missions. The first flight of SLS and the Orion crew 

spacecraft, Artemis I, will lift off from NASA's Kennedy 

Space Center in Florida and send an uncrewed Orion to 

lunar orbit. Artemis I is a rigorous test flight, designed to 

thoroughly test all systems of the SLS rocket prior to crewed 

flights commencing with the Artemis II mission.

This document is designed to serve as a general reference 

for the SLS rocket's initial Block 1 configuration used for 

NASA’s early Artemis missions. SLS capabilities will be 

better understood and refined as the program analyzes 

early flight data and the SLS configuration evolves. In 

addition to providing basic facts about the SLS Block 1 

rocket configured to send the Orion spacecraft to the Moon, 

this document also includes information on SLS design, 

capabilities, major components, and activities such as 

manufacture, test, assembly, launch, and mission. 

Dimensional and performance data used throughout this 

document are approximate for mission-specific, security, 

and proprietary reasons. Dimensions and measures are 

provided in United States customary units as well as metric 

units in parenthesis.

In the Table of Contents, click on the topic to jump to that 

section. For quick navigation in the document, click on the 

gray up arrows at the bottom of each page to return to the 

Table of Contents.

INTRODUCTION

INTRODUCTION

6
SLS represents a bold new vision for NASA’s human 

spaceflight program. In order to make a new generation – 

the Artemis Generation – of crewed missions to the Moon 

possible, the SLS rocket uses proven propulsion systems 

consisting of solid rocket boosters and liquid-fuel RS-25 

engines mated to a new central core stage. 

SLS uses larger solid rocket boosters than the space 

shuttles and liquid hydrogen/liquid oxygen-fed RS-25 

engines opera-ting at a higher thrust level and with new 

controllers. 

The core stage, an all-new development consisting of 

propellant tanks, avionics, and related equipment, houses 

the four RS-25s and provides attach points for the boosters. 

Above the core stage, the Interim Cryogenic Propulsion 

Stage (ICPS) provides in-space propulsion. The launch 

vehicle stage adapter partially encloses the ICPS and 

changes the diameter of the rocket. The Orion stage adapter, 

located between SLS and the Orion crew vehicle, contains 

CubeSat payloads for the Artemis I mission and connects 

the rocket to the Orion spacecraft.

The first section of this guide consists of quick facts and 

introductory information. The following sections go into more 

detail about each of the elements of the Block 1 SLS and 

include additional illustrations, photos, tables, and additional 

infographics. 

The images and illustrations in this guide are all NASA 

images. For downloadable versions of these and many 

other SLS images, go to: https://www.nasa.gov/exploration/

systems/sls/multimedia/images.html

SLS QUICK FACTS

SLS QUICK FACTS

Elements of SLS and Orion

7

This cutaway illustration identifies the major elements of the SLS and Orion 

stack. The SLS portion consists of, from the ground up: twin solid rocket 

boosters with major components labeled, RS-25 liquid-fuel engines, central 

core stage with propellant tanks and flight computers, launch vehicle stage 

adapter, ICPS, and Orion stage adapter. Orion is atop SLS. A 6-ft. figure is 

shown for comparison in the lower left.
SLS Block 1 by the Numbers*

SLS Vehicle

SLS QUICK FACTS

NASA'S SLS BLOCK 1 BY THE NUMBERS

Vehicle design: Evolvable super heavy-lift 

Height: 322.4 ft. (98.3 m)

Weight: 5.74 million lbs. (2,603 t) fueled

3.5 million lbm (1,588 t) unfueled

Main propulsion: Four RS-25 liquid propellant engines and 

two five-segment solid rocket boosters

Maximum thrust: 8.8 million lbs. (39,144 kN) 

Launch thrust: 8.27 million lbs. (36,786 kN)

Maximum speed: 22,670 mph (36,484 km/h) at ICPS 

trans-lunar injection TLI) main engine 

cutoff (MECO)

Single-launch

payload to 

low-Earth orbit: 209,439 lbs. (95 t)

Payload to TLI: > 59,525 lbs. (27 t)

Stacked Artemis I rocket, consisting of SLS and Orion, on the mobile 

launcher. 

Core Stage

Contractor: Boeing

Height: 212 ft. (64.6 m) from forward skirt to 

 engine exhaust exit plane

Diameter: 27.6 ft. (8.4 m)

Weight 

(without engines): 2.4 million lbs. (1,088 t) fueled, 

188,000 lbs. (85.3 t) unfueled

Capacities: 537,000 gal. (2 million L), 

317,000 lbs. (143.8 t) liquid hydrogen fuel;

196,000 gal. (741,941 L), 

1.86 million lbs. (843.7 t) 

liquid oxygen oxidizer

Maximum thrust: Approximately 2 million lbs. (8,896 kN)

Burn Time: 480 sec.

The Artemis I core stage waits in the Vehicle Assembly Building transfer aisle 

before stacking on the mobile launcher.

RS-25 Engines

Contractor: Aerojet Rocketdyne

Height: 14 ft. (4.3 m)

Diameter: 8 ft. (2.4 m)

Weight (each): 7,750 lbs. (3.5 t) 

Propellants: Liquid hydrogen, liquid oxygen

Thrust: 418,000 lbs. (1,852 kN) at launch; 

512,300 lbs. (2,279 kN), maximum at 

109 percent power level

Burn time: 480 sec.

The Artemis I RS-25 engines installed in the core stage during assembly at 

NASA’s Michoud Assembly Facility in New Orleans.

8 *Data are Approximate
Contractor: Northrop Grumman

Height: 177 ft. (54 m)

Diameter: 12 ft. (3.7 m)

Weight (each): 1.6 million lbs. (726 t) loaded, 

219,000 lbs. (99.3 t) empty

Solid rocket motor: Five propellant segments 

Propellant: Polybutadiene acrylonitrile (PBAN)

Thrust: 3.3 million lbs. (14,679 kN) each at 

launch; 3.6 million lbs. (16,014 kN) 

each maximum

Burn time: 126 sec.

Solid Rocket Boosters

SLS QUICK FACTS

NASA'S SLS BLOCK 1 BY THE NUMBERS

9

Interim Cryogenic Propulsion 

Stage (Upper Stage)

Artemis I five-segment solid rocket boosters stacked on the mobile launcher.

Contractor: Boeing/United Launch Alliance

Designation: Interim Cryogenic Propulsion Stage 

(modified Delta Cryogenic Second Stage)

Height: 45 ft. (13.7 m)

Diameter: 16.7 ft. (5.1 m)

Weight: 72,197 lbs. (32.7 t) fueled; 

8,200 lbs (3.7 t) unfueled

Engine: Aerojet Rocketdyne RL10B-2,

RL10C-2 (Artemis II/III) 

Propellants: Liquid hydrogen/liquid oxygen 

Maximum thrust: 24,750 lbs. (110 kN)

Reaction Control 

System (RCS): Hydrazine

The Artemis I ICPS at Kennedy prior to stacking.

Launch Vehicle Stage Adapter

Contractor: Teledyne Brown Engineering

Height: 27.5 ft. (8.4 m)

Diameter: 27.5 ft. (8.4 m) bottom, 

16.5 ft. (5.0 m) top

Weight: 10,000 lbs. (4.5 t)

The Artemis I launch vehicle stage adapter arrives at the Vehicle Assembly 

Building for stacking on the Artemis I rocket.

Orion Stage Adapter

Contractor: NASA Marshall Space Flight Center

Height: 5 ft. (1.5 m)

Diameter: 18 ft. (5.5 m)

Weight: 1,800 lbs. (0.8 t)

Available volume

for payloads: 516 ft.3 (14.6 m3)

Orion stage adapter complete and ready for CubeSats.

*Data are Approximate
Secondary Payloads

Ten CubeSat payloads for Artemis I, each measuring 

4.4 in. (11.1 cm) x 9.4 in. (22.8 cm) x 14.4 in. (36.6 cm); each 

CubeSat is 6U (1U [unit] = 10 cm x 10 cm x 10 cm), not to 

exceed 30 lbs. (14 kg)

Moon

Lunar IceCube – Morehead State University, Kentucky 

Searching for water in all forms and other volatiles with an 

infrared spectrometer

LunaH-Map – Arizona State University, Arizona 

Creating higher-fidelity maps of near-surface hydrogen in 

craters and other permanently shadowed regions of the 

lunar South Pole with neutron spectrometers

OMOTENASHI – Japanese Aerospace Exploration Agency 

(JAXA), Japan Developing world’s smallest lunar lander and 

studying lunar environment

LunIR – Lockheed Martin, Colorado 

Performing advanced infrared imaging of the lunar surface

Sun

CuSP – Southwest Research Institute, Texas 

Measuring particles and magnetic fields as a space 

weather station

Asteroid

SLS QUICK FACTS

SECONDARY PAYLOADS

10

NEA Scout – NASA's Marshall Space Flight Center, Alabama 

Traveling by solar sail to a near-Earth asteroid and taking 

pictures and other characterizations of its surface 

Earth

EQUULEUS – University of Tokyo/JAXA, Japan 

Imaging Earth’s plasmasphere for a better understanding of 

Earth’s radiation environment from Earth-Moon Lagrange 2 

point OR Lagrange Point 2

The Artemis I Orion stage adapter with mounting brackets for secondary 

payloads.

Artist concept of Artemis I secondary payload, NEA Scout, with its deployed 

solar sail on its way to an asteroid.

Preparing the NEA Scout payload for its flight aboard Artemis I.
Other Missions

SLS QUICK FACTS

SECONDARY PAYLOADS

11

BioSentinel – NASA's Ames Research Center, California 

Using single-celled yeast to detect, measure, and compare 

the impact of deep space radiation on living organisms over 

a long period of time

ArgoMoon – European Space Agency (ESA)/ASI, 

ArgoTec, Italy 

Observing the ICPS with advanced optics and software 

imaging system

Centennial Challenges

Team Miles – Florida

Demonstrating propulsion using plasma thrusters and competing in NASA’s Deep Space Derby

The NEA Scout team at NASA’s Jet Propulsion Laboratory, which supplied science instruments to characterize a target near-Earth asteroid.
NASA’s SLS is the world’s most powerful 

rocket and the backbone of NASA’s human 

lunar exploration program. No other rocket 

can send astronauts and the Orion spacecraft 

directly to the Moon for the Artemis missions. 

SLS provides an unmatched capability to 

deliver greater mass and volume than any 

current launch vehicle for both human and 

robotic exploration of the Moon, Mars, and 

the outer planets.

SLS was established by the NASA 

Authorization Act of 2010. The program was 

created at Marshall in 2011 and received 

funding in FY2012. SLS is the world’s first 

exploration-class launch vehicle since the 

Apollo Program’s Saturn V. 

Along with SLS, NASA’s Exploration 

Systems Development Mission Directorate in 

the Human Exploration and Operations 

Mission Directorate is developing the EGS

and the Orion spacecraft for crew. 

Orion, managed at NASA’s Johnson Space 

Center in Houston, is a spacecraft designed 

to carry astronauts on exploration missions 

into deep space. EGS has converted facilities 

at Kennedy into a next-generation spaceport 

capable of supporting launches by multiple 

types of vehicles. 

SLS is designed to evolve from an initial 

Block 1 configuration for the early Artemis 

uncrewed test and crew missions to a 

Block 1B vehicle capable of dual crew/cargo 

missions or dedicated large cargo missions. 

The ultimate Block 2 configuration design can 

provide the same dual crew/cargo and cargoonly configurations with even greater payload 

mass and volume capability.

SLS OVERVIEW

SLS OVERVIEW

12
SLS OVERVIEW

SLS DESIGN

SLS Design: Chosen From Thousands of Options

Super heavy-lift has been validated by numerous NASA 

and external studies, such as the Space Transportation 

Architecture Study in 1986 and the Exploration Systems 

Architecture Study in 2005. As NASA looked toward the 

space shuttle’s retirement, the agency focused on a return 

to human deep space exploration and the needed super 

heavy-lift capability to make those missions a reality.

13

The Artemis I core stage is lowered between the SLS solid rocket boosters in the Vehicle Assembly Building. The SLS design uses a proven propulsion 

system of solid rocket boosters and liquid-fuel RS-25 engines to launch more payload to the Moon than any rocket since the Saturn V.
In defining the vehicle that would become SLS, NASA 

evaluated thousands of combinations of attributes such 

as propulsion systems; stages; boosters; performance; 

development and operations cost; mission complexity, 

reliability, and risks; and the ability to maintain critical 

industry base skills. The result: SLS. The evolvable rocket, 

which can accommodate crew or cargo (with payload 

fairing) configurations, with a proven propulsion system, 

provides a safe, human-rated launch capability. 

SLS benefits from NASA’s half-century of experience with 

efficient liquid oxygen and liquid hydrogen propellants 

and from advances in technology and manufacturing 

practices. Further, by using common design elements, the 

SLS interfaces with the ground systems at Kennedy, with 

SLS OVERVIEW

SLS DESIGN

the Orion spacecraft, and with future payloads will remain 

consistent over time, reducing complexity of deep space 

missions. 

The SLS operational scheme takes advantage of 

resources established for the space shuttle, including the 

workforce, manufacturing processes, tooling and facilities, 

transportation logistics, launch infrastructure, and liquid 

oxygen/liquid hydrogen propellants. By using heritage 

shuttle engines and boosters upgraded for SLS, the 

program saved the time and cost typical in developing new 

propulsion systems, and the SLS Program begins flights 

with proven engine and booster hardware transferred from 

the Space Shuttle Program.

RS-25 hot fire testing at NASA's Stennis Space Center in Bay St. Louis, Mississippi, helped qualify engines to extreme SLS environments.

With the largest payload mass and volume of any existing 

rocket, SLS represents greater safety, less risk, and 

increased probability of mission success in the dynamic, 

unforgiving environments of spaceflight. More mass and 

volume translate into fewer launches of fewer pieces 

requiring less assembly time in orbit. 

On the ground, it also translates into simpler hardware 

design and less transportation, storage, processing, launch 

operations, and launch pad turnaround activities. SLS was 

designed for the most challenging deep space missions 

involving strategic commitments of national resources, 

national prestige, and human life. SLS represents the best 

balance of mission performance, safety, cost, affordability, 

and risk.

14
SLS OVERVIEW

COMMON ELEMENTS AND EVOLVABILITY

Common Elements and Evolvability

15

SLS evolvability supports a robust resumption of human 

exploration beyond low-Earth orbit and an expeditious 

growth path as exploration missions become more complex 

and demanding. 

All variants of the basic SLS design are based on common

propulsion components:

– A central core stage housing propellant tanks, engines, 

avionics, and attach points for a pair of solid rocket 

boosters.

– Four liquid propellant engines powered by cryogenic 

liquid hydrogen and cryogenic liquid oxygen from the 

core stage.

– Two solid-fuel, side-mounted booster rockets that 

provide the majority of thrust and steering for the rocket 

during the first two minutes of flight, after which they are 

jettisoned.

– An in-space upper stage fueled by liquid hydrogen and 

liquid oxygen.

SLS Evolutionary Path

SLS Block 1 with an uncrewed Orion will launch the Artemis I mission. Following the first three Artemis missions, SLS will evolve to a more powerful Block 

1B configuration with a new Exploration Upper Stage replacing the ICPS. The ultimate variant, Block 2, will incorporate evolved boosters to increase payload 

mass to TLI to at least 101,000 lbs. (46 t).
Each succeeding SLS block variant grows more capable 

through upgrades to the engines, boosters, and upper 

stage, providing a flexible platform for a variety of 

human and robotic deep space missions, rather than 

requiring development of entirely new rockets to increase 

performance. In addition to flying Orion, SLS can also be 

outfitted with wide-diameter payload fairings in varying 

lengths.

SLS OVERVIEW

COMMON ELEMENTS AND EVOLVABILITY

The uncrewed Artemis I mission will be launched on an SLS 

Block 1 vehicle. Artemis II and Artemis III, the first crewed 

SLS/Orion missions, also will be launched on Block 1 

vehicles. The Block 1 SLS rocket towers 322.4 ft. (98.3 m), 

and weighs 5.74 million lbs. (2,603 t) fueled. During ascent, 

the rocket generates 8.8 million lbs. (39,144 kN) of thrust – 

more than the Saturn V that launched the Apollo missions to 

the Moon. SLS will transport approximately 59,525 lbs. (27 t) 

to trans-lunar injection.

16

The 212-ft. (64.6 m) core stage for Artemis I in the transfer aisle of the Vehicle Assembly Building in preparation for lifting and integration on the mobile 

launcher. Manufactured by Boeing at Michoud, the stage houses the four RS-25 engines, propellant tanks, and flight computers. Too large to ship over land, 

NASA's barge Pegasus transported the Artemis I core stage to Stennis for a ‘Green Run’ test campaign and then to Kennedy for integration with the rest of 

the vehicle.

The core stage, manufactured by Boeing at Michoud, 

serves as the backbone of the SLS rocket. The core stage 

propellant tanks hold 537,000 gal. (2 million L) of cryogenic 

liquid hydrogen and 196,000 gal. (741,941 L) of cryogenic 

liquid oxygen. Total propellant weight is 2.2 million lbs. (998 t). 

The stage will operate for approximately 480 seconds, after 

which separation from the ICPS, Orion stage adapter, and 

Orion will occur.

The core stage engine section contains four RS-25 engines

manufactured by Aerojet Rocketdyne and transferred from 

the Space Shuttle Program with new controllers and minor 

modifications for SLS requirements. 
SLS OVERVIEW

COMMON ELEMENTS AND EVOLVABILITY

The solid rocket boosters, manufactured by Northrop 

Grumman, are five-segment solid propellant boosters 

based on the space shuttle’s four-segment boosters. 

The SLS boosters also use hardware transferred from 

the Space Shuttle Program, including steel cases, nose 

cones, frustums, aft skirts, and more. The SLS solid rocket 

boosters are the largest and most powerful solid rocket 

boosters ever built for spaceflight. In addition to the extra 

propellant segment, the SLS boosters incorporate new 

insulation, avionics, modified propellant grain design, and 

nozzle design. 

The upper stage on the SLS Block 1 is the ICPS, a 

commercial stage modified for the SLS mission. The ICPS is 

a liquid hydrogen/liquid oxygen system with a single Aerojet 

Rocketdyne RL10 engine. The ICPS, manufactured by 

Boeing/United Launch Alliance (ULA) in Decatur, Alabama, 

performs the trans-lunar injection engine burn that sends 

Orion on its course to the Moon. It also contains the 

avionics to fly the mission after core stage separation until 

Orion separates from the ICPS. 

The ICPS is partially enclosed by a launch vehicle stage 

adapter, which has a separation system that fires to 

separate itself and the core stage from the ICPS, Orion 

stage adapter, and Orion. On top of the ICPS, the Orion 

stage adapter connects the Orion spacecraft to SLS. The 

Orion stage adapter will also carry the Artemis I CubeSat 

payloads to deep space. These small science experiments 

and technology demonstrations will be deployed after Orion 

separates from the ICPS and Orion stage adapter.

SLS: SUPER HEAVY-LIFT ROCKET FOR GAMECHANGING SPACE EXPLORATION MISSIONS

– Block 1 in its crew configuration (with Orion) will 

transport more than 209,000 lbs. (95 t) to lowEarth orbit and more than 59,000 lbs. (27 t) to TLI. 

– Block 1B’s crew variant will launch more than 

231,000 lbs. (105 t) to low-Earth orbit and more 

than 83,000 lbs. (38 t) to TLI. 

– Block 2 in the crew configuration will carry more 

than 286,000 lbs. (130 t) to low-Earth orbit and 

more than 94,000 lbs. (43 t) to TLI. 

– The design for each variant’s cargo version is 

capable of launching thousands more pounds 

to low-Earth orbit and TLI compared to its crew 

variant. 

– SLS with a 27.6-ft. (8.4 m)-diameter payload 

fairing offers immense volume for large payloads, 

such as habitat modules, space telescopes, and 

interplanetary probes. Additional stages can even 

be encapsulated with a spacecraft to make highenergy missions to the outer planets possible. 

– The ultimate Block 2 design in its cargo 

configuration can launch more than 101,000 lbs. 

to TLI and more than 80,000 lbs. to Mars.

The initial SLS Block 1 rocket configuration is manifested 

for the first three Artemis missions to the Moon. The Block 

1B variant will follow the Block 1 rocket design. The Block 

1B variant incorporates several upgrades to improve SLS 

performance, allowing the rocket to launch larger and heavier 

payloads to deep space destinations. 

SLS Block 1B uses the same core stage and twin fivesegment solid rocket boosters as the Block 1 rocket. Newproduction RS-25 engines will provide slightly more thrust 

than the shuttle-era engines and cost 30 percent less to 

manufacture. 

More Powerful Rockets for Future Missions

The primary increase in performance for the Block 1B 

rocket will come from replacing the single-engine ICPS with 

a new, more powerful four-engine Exploration Upper Stage 

(EUS). The Block 2 variant retains the core stage, RS-25 

engines, and EUS but replaces the Block 1 steel case 

booster motor design with a lighter composite case, new 

propellant formulation, and other upgrades that increase 

overall payload performance.

17
SLS OVERVIEW

SLS VEHICLE-LEVEL TESTING

SLS Vehicle-Level Testing

18

The SLS Program conducted extensive testing on the 

rocket, ranging from basic structural materials testing to 

full-up integrated testing of the entire Artemis I SLS rocket. 

Element-level testing of the engines, boosters, core stage, 

and upper stage elements are discussed in those sections. 

Avionics, the hardware and software that serve as the 

“brains” of the rocket, were developed and tested at 

Marshall. The Integrated Avionics Test Facilities team 

provided the structure and simulation capability to model the 

environments the rocket will experience during launch. 

The avionics team was able to put development and flightlike hardware and software to the test in a virtual launch 

environment. Using specially developed software tools, the 

team simulated a variety of weather conditions as well as 

the Earth’s rotation, SLS performance, and other conditions. 

They exercised flight avionics with engines, boosters, 

and Orion computer systems in combination with these 

additional variables. In fact, the team flew thousands of 

virtual missions in the lab before the Artemis I mission.

In addition to avionics testing, engineers at Marshall 

conducted a test campaign consisting of dozens of acoustic 

tests on a five-percent scale SLS model. The scale-model 

acoustic test program helped engineers understand how 

sounds and vibrations could affect SLS, its crew, and 

payloads in the launch environment. The small-scale model 

had four operational liquid engines and two solid rocket 

motors to represent SLS propulsion. The series also tested 

the water sound suppression system for the launch pad.

In another test, engineers developed algorithms that could 

make an F/A-18 test aircraft fly like SLS to test adaptive SLS 

flight control software capable of responding to abnormal 

conditions like higher thrust or wind gusts to see if the flight 

control system responds as designed.

Wind tunnel tests helped refine designs and smooth airflow 

in flight, determine the effects of wind before the rocket 

clears the launch tower, how SLS heats up as it pushes 

through the atmosphere, and how it responds to buffeting 

at or near the speed of sound. Engineers at NASA's 

Ames Research Center in California and NASA'S Langley 

Research Center in Hampton, Virgina, tested accurate scale 

models of the SLS crew and cargo variants in wind tunnel 

facilities at those centers. 

In 2013, NASA conducted a series of F/A-18 research flights to test SLS 

prototype software, including the previously adaptive augmenting control 

component. Adaptive augmenting contol benefits total attitude control and 

increases flight control system performance when excessive tracking error 

is present and decreases responsiveness to undesirable frequency content. 

It expands the envelope under which the flight control system is capable of 

safely flying the vehicle.

The Systems Integration Lab at Marshall includes flight computers and 

avionics functionally identical to the core stage avionics to test all systems 

prior to flight.
SLS OVERVIEW

SLS VEHICLE-LEVEL TESTING

While the scale model acoustic test, adaptive flight control 

software, and wind tunnel tests were conducted relatively 

early in the SLS development phase, a major series of 

integrated vehicle tests was also conducted when the rocket 

was assembled in Kennedy's Vehicle Assembly Building. 

The Integrated Test and Check Out (ITCO) series, performed 

after SLS was assembled in the Vehicle Assembly Building 

and at the launch pad, thoroughly tested all the systems, 

end-to-end, prior to launch. Tests included powering up the 

rocket, ensuring avionics communicated with each other 

and with NASA’s tracking system, a “wet dress rehearsal” to 

practice filling and draining propellant tanks with cryogenic 

propellant, and more. Also before launch, engineers will 

perform a test on the SLS rocket's flight termination 

system–and capability required on all rockets-and is only 

used if the rocket's flight has to be ended early.

For the early part of this test series, engineers used an Orion 

simulator instead of the Artemis I spacecraft. The Artemis I 

core stage was attached to the solid rocket boosters 

previously stacked on the mobile launcher. The launch 

vehicle stage adapter and ICPS were also integrated with 

the core stage. Because CubeSat payloads were being 

installed in the Orion stage adapter, an Orion stage adapter 

test article was stacked on the ICPS. Finally, an Orion/

service module simulator was mated to the Orion stage 

adapter test article while Orion’s launch abort system was 

being installed on the Artemis I Orion.

Marshall’s Systems Integration Lab has the capabilities to allow the software

team to fly thousands of virtual launches in a simulated environment that 

included wind, weather, and Earth’s rotation. 19

An Orion simulator mimicked the weight and weight 

distribution of the real spacecraft. The ITCO marked a 

key milestone prior to flight. The test series proved the 

functionality and system interoperability of flight and ground 

systems and provided key data on the vehicle design for 

future missions. During testing, the team collected data 

on vibrations, communications, launch pad umbilical 

retraction, avionics operation, and core stage and ICPS 

main propulsion systems, among other things. 

Ames produced a visualization of SLS exhaust gas flow during liftoff from 

Launch Complex 39B to accurately understand how liquid and gases 

flowing during launch can cause various kinds of waves at the launch pad.

A five-percent scale model of SLS undergoes acoustic testing in 2014 at 

Marshall. 
SLS OVERVIEW

SLS VEHICLE-LEVEL TESTING

20

TEN ITCO TESTS TO PREPARE FOR FLIGHT:

1. Modal Tests: These tests characterize vehicle 

dynamics and include booster push/pull testing, 

a modal tap test, and integrated modal testing on 

the mobile launcher and crawler-transporter with 

Orion stage adapter test article and Orion mass 

simulator using hydraulic shakers and calibrated 

hammers.

2. Interface Verification Test: Also performed with 

the Orion stage adapter test article and the Orion 

simulator "as well as" with the Artemis I Orion, 

this test verifies functionality and interoperability 

of SLS-to-Orion interfaces.

3. Communications End-to-End Test: This critical 

test validates communications between the 

vehicle and tracking network.

4. Umbilical Release and Retract Test:

Testing the timing of booster arming and firing 

and the command for umbilical release.

5. Vehicle Assembly Building Project-Specific 

Engineering Test: Element-level testing of SLS in 

the Vehicle Assembly Building.

6. Countdown Sequence Test: Training the launch 

team with Artemis I flight hardware in the loop.

7. Flight Safety System: Rehearsal for preand post-wet dress and ordnance and flight 

termination system communications.

8. Dynamic Rollout Test: Rolling the vehicle

from the Vehicle Assembly Building to Launch 

Complex 39B and back to compare actual loads 

to analytical models.

9. Pad Project-Specific Engineering Test: At the 

launch pad, testing radio frequency; guidance, 

navigation, and control; and performing final 

ordnance tests.

10. Wet Dress Rehearsal: Testing propellant 

loading procedures, structural response, thermal 

conditioning and loading procedures; vehicle 

control system; avionics and software checkout; 

electromagnetic interference; guidance and 

navigation; main propulsion system; and engine 

and booster nozzle steering.

Modal testing underway in High Bay 3 inside the Vehicle Assembly Building 

at Kennedy, using the Orion stage adapter structural test article and the 

mass simulator for Orion. The test hardware articles have the same weight 

and mass characteristics as their respective flight components.
SLS OVERVIEW

SLS VEHICLE-LEVEL TESTING

At the conclusion of ITCO, the Orion mass simulator and 

Orion stage adapter test article were removed from the 

stack. The Artemis I Orion stage adapter, with CubeSat 

payloads installed, and the Orion spacecraft were placed on 

the integrated stack for flight.

The final major test of the ITCO series was wet dress 

rehearsal. For this test of the full flight stack, the crawlertransporter carried the Artemis I rocket and Orion spacecraft 

on the mobile launcher to Launch Complex 39B. There, 

the rocket – and the launch team – went through a full 

countdown rehearsal, including power up, systems 

checkout, and filling the entire rocket and spacecraft with all 

the propellants.

21

A scale model of SLS was tested in an 11-by 11-ft. (3.4-by 3.4-m) Transonic Wind Tunnel at Ames. Data from the wind tunnel tests at Ames and Langley was 

used to improve the design and stability of SLS.
Super Heavy Lifting on the Ground: 

SLS Transportation, Logistics, and Pathfinders 

SLS OVERVIEW

TRANSPORTATION, LOGISTICS, 

AND PATHFINDERS

NASA has not built a rocket on the scale of SLS, able to 

take astronauts and cargo to the Moon, since the Saturn V 

of the Apollo Program in the 1960s and 1970s. 

To give transportation and ground handling crews the 

opportunity to rehearse and perfect logistics and handling 

procedures prior to receiving Artemis I hardware, the 

SLS Program provided several full-scale “pathfinders” to 

pave the way for smooth shipping, handling, and lifting 

operations.

The core stage pathfinder is a full-scale mockup 

structurally similar to the core stage in shape, size, 

weight, center of gravity, and handling interfaces. Lacking 

the internal tanks and equipment of a flight stage, the 

pathfinder was used to practice transport, handling, and 

lifting operations at Michoud, Stennis, and Kennedy before 

teams worked with the Artemis I core stage.

Moving flight hardware during manufacturing and testing 

within facilities and onto rail cars, barges, and the Super 

Guppy requires care and specialized equipment. These 

elements are too large to transport using dollies and hand 

trucks! While the RS-25 engines move by truck and the 

booster motor segments travel by rail, the core stage, 

ICPS, and launch vehicle stage adapter require their own 

transportation and handling equipment. 

NASA’s Super Guppy aircraft transported the Orion stage 

adapter to Kennedy.

22

The core stage pathfinder mimics the structure of the SLS core stage, providing transportation, logistics, and lifting crews with the opportunity to rehearse with 

full-scale hardware before handling one-of-a-kind flight hardware.
SLS OVERVIEW

TRANSPORTATION, LOGISTICS, 

AND PATHFINDERS

NASA’s barge Pegasus is the largest vehicle used to 

transport SLS elements as well as the core stage pathfinder. 

Pegasus ferried the Artemis I core stage from Michoud 

where it was manufactured, to Stennis for Green Run testing 

to hot fire the core stage. After Green Run, Pegasus carried 

the core stage to Kennedy. Pegasus also transported the 

launch vehicle stage adapter from Marshall to Kennedy.

Pegasus was designed and built in 1999 to transport space 

shuttle external tanks from Michoud to Kennedy. It replaced 

the Poseidon and Orion barges that were used to carry 

Saturn rocket stages and hardware for the Apollo Program. 

Pegasus was modified in 2014 to carry the longer SLS core 

stage. A 115-ft. (35 m) section was removed and replaced 

with a 165-ft. (50 m) section capable of carrying more 

weight and lengthening Pegasus from 260 ft. (79 m) to 310 

ft. (94 m). Pegasus has no engines and instead is moved by 

tugboats and towing vessels.

ULA uses its R/S RocketShip, formerly the Delta Mariner, 

to transport the ICPS from its rocket factory in Decatur, 

Alabama, to the Delta Operations Center near Kennedy prior 

to stacking in the Vehicle Assembly Building. 

For surface transportation, SLS relies on specialized 

Ground Support Equipment (GSE). This is a set of modular 

equipment ranging from smaller brackets, shackles, and 

pins that secure the giant rocket hardware to the slow, 

flatbed motorized transports that move rocket components 

between buildings, barge, and test stands. 

A full-scale SLS core stage pathfinder was used by crews at Michoud, 

Stennis, and Kennedy to practice handling, logistics, crane lifts, and other 

operations before working with Artemis I flight hardware.

Engineers and technicians at Kennedy used the 212-ft. (65 m) pathfinder 

core stage simulator to practice lifts and moves in the Vehicle Assembly 

Building.

23
SLS OVERVIEW

TRANSPORTATION, LOGISTICS, 

AND PATHFINDERS

Like the flight hardware that depends on it, the GSE was 

designed and built to exact specifications, and its uses – 

and instructions for those uses – are documented in detail. 

Every move is carefully choreographed by the operations 

teams that use it. 

NASA's barge Pegasus, used to transport external tanks during the Space 

Shuttle Program, was lengthened and strengthened to transport the SLS 

core stage. A 115-ft. (35 m) section of the barge was removed and replaced 

with a specially reinforced 165-ft. (50 m) section to increase the weight 

Pegasus can carry. The length of the barged increased from 260 ft. (79 m) to 

310 ft. (94 m).

EGS and Jacobs technicians worked with inert booster motor segments as 

pathfinders in Kennedy's Rotation, Processing, and Surge Facility (RPSF) 

and Vehicle Assembly Building before assembling the Artemis I booster 

motor segments.

24

NASA's Super Guppy cargo aircraft transported the Orion stage adapter from Marshall, where it was manufactured, to Kennedy.
SLS OVERVIEW

EXTERIOR FEATURES OF SLS 

Exterior Features of SLS

Thermal Protection System

SLS has several distinctive external features. The orange 

color of the core stage is the thermal protection system, or 

spray-on foam insulation. This insulation, along with other 

materials such as cork, provides thermal protection for every 

part of the rocket, although it is most visible on the core 

stage. The insulation is flexible enough to move with the 

rocket but rigid enough to take the aerodynamic pressures 

as SLS accelerates from 0 to 17,400 mph (28,003 km/h) and 

soars to more than 100 mi. (161 km) above Earth in just 

8 minutes.

The cryogenic propellant (liquid hydrogen and liquid oxygen) 

that powers the RS-25 engines must stay extremely cold 

to remain liquid. Hydrogen must remain at -423 degrees 

Fahrenheit (-253 degrees Celsius) and oxygen at -297 

degrees Fahrenheit (-183 degrees Celsius). If temperatures 

rise too high, the propellant will become a gas. 

Materials engineers qualified the third-generation, orangecolored spray-on foam insulation to meet the harsh 

environments that the SLS will experience. At the same 

time, they made the foam more environmentally friendly. 

When the foam is applied, it gives the rocket a light-yellow 

color that the Sun's ultraviolet rays eventually "tan," giving 

the SLS core stage its signature orange color.

The SLS gets its signature orange color when its spray-on foam insulation darkens with exposure to sunlight. The core stage below the work platform was 

exposed to months of sunlight during Green Run testing at Stennis, while the launch vehicle stage adapter being lowered into place above the platform has 

been stored indoors since its completion.

25
In addition to the SLS core stage’s distinctive orange color, 

several other markings are visible on the outside of the 

rocket. The most visible are the national and agency livery 

markings such as “USA,” the U. S. flag, the NASA “meatball” 

and “worm” marks, and the ESA mark. 

SLS, as well as the Orion crew spacecraft and the mobile 

launcher, also have black-and-white markings that play 

an important role in Artemis I. These photogrammetric 

markings are the black and white checkerboards, squares, 

and circles on the outside of the rocket. These markings 

serve as imagery references for engineering photo and 

video documentation of SLS attitude and position relative to 

ground structure during liftoff and ascent. Markings range in 

size from 0.2 in. (0.5 cm) to 3 x 3 ft. (0.9 x 0.9 m). On the solid 

rocket boosters, some of the markings are a multi-checkered 

pattern measuring 24 x 130 in. (0.6 m x 3.3 m).

Some of the markings are visible only to internal cameras 

and will capture separation and jettison events. The launch 

vehicle stage adapter has eight internal markings; the ICPS 

has 12; the forward bay of the European Service Module has 

30; the spacecraft adapter has 12; and spacecraft adapter 

jettison panel 1 has 12 markings.

Engineers are interested in every movement of the rocket, 

both independently and in relation to the mobile launcher, 

in every phase of flight, from the launch pad to its return to 

Livery and Photogrammetric Markings

SLS OVERVIEW

EXTERIOR FEATURES OF SLS 

Earth. Most of the markings will be used during separation 

events, such as SLS from the mobile launcher, boosters from 

the core stage, core stage/launch vehicle stage adapter from 

the ICPS, and ICPS/Orion stage adapter from Orion and its 

service module.

The imagery markings help to characterize these 

movements, and the data will feed back into computer 

models to understand actual vs. predicted movements. 

Every key launch event and its marking were analyzed for 

placement. Key considerations were where to place onboard 

cameras to survive the harsh launch environment, as well as 

where ground cameras are located. 

SLS has four cameras on the engine section that look 

forward, two on the intertank looking aft, and two inside the 

launch vehicle stage adapter to capture the ICPS separation 

event. The engine section cameras are forward-facing and 

have a tilt of 10 degrees and a pan of 0 degrees. The aftfacing intertank cameras have a tilt of 2.5 degrees and a pan 

of 5 degrees. There are more than 150 ground cameras used 

for inspecting or monitoring the vehicle during launch. A few 

of those are for public affairs purposes, but most of them 

provide imagery to engineers. For Artemis I, NASA will also 

have one WB-57 aircraft capturing aerial imagery. There are 

also plans for other airborne and ship-based imagery during 

re-entry and recovery of Orion.

Technicians with lead solid rocket boosters contractor Northrop Grumman paint photogrammetric markings on one segment of an SLS solid rocket motor. 

The black-and-white targets painted on each element of the rocket provide targets for cameras, which then use those positions compared with fixed 

positions on the ground and on the mobile launcher to precisely locate SLS in space.

26
SLS OVERVIEW

EXTERIOR FEATURES OF SLS 

As a test flight, the basic Artemis I mission is to successfully 

confirm performance and operational capability of the 

integrated flight and ground elements in performing the 

lunar mission, including for SLS countdown, launch, ascent, 

and putting Orion on course to the Moon. Success will be 

measured by flight data collected on the ground and in flight. 

Much of that flight data will be generated by computers on 

the engines, boosters, core stage, ICPS, and thousands of 

sensors attached to the rocket. 

That data and instrumentation to capture the data is divided 

into three categories: operational flight instrumentation, 

engineering flight instrumentation, and development 

flight instrumentation. Operational data is hardware and/

or software required to operate the vehicle. Engineering 

data is hardware or software data mainly used for postflight performance analysis. Developmental data is used to 

increase confidence in the computer models – predictions – 

of how the vehicle should perform.

Instrumentation and Rocket Telemetry

SLS will transmit data from more than 27,000 sources of 

data to the ground for analysis. Of those, more than 20,000 

channels will be operational and engineering data with the 

rest devoted to development data. Each element – core 

stage, engines, boosters, payload, command telemetry, 

and imagery – has a specified allocated bandwidth for 

transmission during flight.

All this data will be collected and analyzed to ensure SLS 

is the most reliable, highest-performing, and safest rocket 

that NASA has ever sent to deep space. It is part of the 

Artemis I test flight philosophy. Engineers will rigorously 

test all the systems in deep space, because Artemis I is 

just the beginning. Following Artemis I, crewed flights will 

commence, culminating with the first woman and the first 

person of color walking on the Moon.

Part of the Kennedy Uplink Station, the S-band ground tracking system at Kennedy provides crucial tracking and communication capabilities following liftoff 

of SLS and Orion.

27
THE ROLE OF SLS IN LAUNCHING ARTEMIS I

THE ROLE OF SLS IN 

LAUNCHING ARTEMIS I

*Numbers based on 2021 mission analysis as this guide was in development and will vary based on season, 

launch date, and time. Numbers are approximated to meet security, export control, and proprietary requirements.

The Artemis I countdown will begin with a “call to stations” 

for engineers and technicians working operations consoles 

at the Launch Control Center (LCC) at Kennedy, the Mission 

Control Center at Johnson, the SLS Engineering Support 

Center (SESC) at Marshall, and several contractor locations. 

28

Artemis I will provide the first integrated flight test of SLS, 

Orion, and ground processing and launch facilities at 

Kennedy. For Artemis I, SLS will launch an uncrewed Orion 

to a distant retrograde orbit about the Moon in a flight test 

designed to verify vehicle models, manufacturing, and 

operations. The data engineers receive from Artemis I on the 

vehicle’s performance will be valuable for future flights with 

astronauts. 

Artemis I: SLS Flight Profile

Major events of the Artemis I flight, including solid rocket booster jettison, core stage and launch vehicle stage adapter separation, and ICPS and Orion stage 

adapter separation from Orion. Following separation with Orion, CubeSat payloads will be released into deep space.
THE ROLE OF SLS IN LAUNCHING ARTEMIS I

For the flight, SLS will lift off, and the solid rocket boosters 

will burn through their propellant and separate after 

approximately two minutes. The core stage and RS-25s will 

deplete propellant after approximately six more minutes. 

After main engine cutoff, the ICPS, Orion stage adapter, and 

Orion will separate from the core stage and launch vehicle 

stage adapter. Engineers on the ground will verify the health 

of ICPS and Orion systems before giving the approval 

for the TLI burn by the ICPS. The TLI maneuver precisely 

targets a point about the Moon that will guide Orion close 

enough to be captured by the Moon’s gravity.

Following the TLI burn, the ICPS separates from Orion. 

Orion’s service module propels it from this point, making 

course correction burns as needed to begin its three-week 

mission. Its mission almost complete, the upper stage, 

meanwhile, continues on a similar path, deploying several 

CubeSats along the way to study the Moon or head farther 

out to deep space destinations.

The boosters will fall into the Atlantic Ocean about 140 mi.

(225 km) off the Florida coast, north of the Bahamas. The 

core stage/launch vehicle stage adapter will fall into the 

Pacific Ocean east of Hawaii, west of Baja, California. After 

Orion separation, the ICPS will enter heliocentric (around the 

Sun) orbit.

Flight testing mitigates risk by collecting flight data to further 

anchor engineering models used to certify the design. Each 

program – EGS, Orion, and SLS – has objectives for the 

Artemis I flight test mission. 

Artemis I is a test flight to verify SLS vehicle models, 

manufacturing, and operations. The measure of mission 

success will be the data returned on the vehicle and its 

performance. 

ARTEMIS I OBJECTIVES SPECIFIC TO SLS:

– Testing pre-launch operations.

– Collecting flight telemetry and imagery to 

evaluate structural integrity of the vehicle from 

ascent through ICPS/Orion separation.

– Testing the core stage flight computers’ ability 

to run an autonomous launch sequence.

– Initiation of hydrogen burn-off igniters. 

– Guidance and navigation. 

– Core stage engine ignition, throttling, steering, 

and cutoff.

– Booster ignition, separation, and ocean impact.

– Mobile launcher umbilical separation.

– Liftoff and launch tower clearance.

– Performance of a heads-down roll maneuver.

– Transonic, maximum dynamic pressure, and 

maximum acceleration.

– Testing communication systems.

– Core stage/ICPS staging and core stage 

ocean impact.

– ICPS operations, including steering, engine 

start and shutdown, perigee raise and TLI 

engine burns, and disposal maneuver.

– Orion/ICPS staging.

– Secondary payload deployment.

29

Technicians installed the liquid hydrogen tank structural test article in its 

test stand at Marshall at night when winds were minimal.
ARTEMIS I SECONDARY PAYLOADS

The unmatched SLS payload mass capability and the 

unused volume of the Orion stage adapter provide a rare 

opportunity for small, low-cost science and technology 

experiments to be deployed into deep space.

These secondary payloads are not much larger than a 

shoebox but contain science and technology investigations 

or technology demonstrations that help pave the way for 

future deep space human exploration. International space 

agency partners and universities are involved with several of 

the CubeSat payloads.

Artemis I Secondary Payloads

The Artemis I CubeSats are 6U in size. One U – or unit – is 

10 cm x 10 cm x 10 cm. The Artemis I payloads are limited 

to about 30 lbs. (14 kg) each. Several of the CubeSats 

chosen to fly on Artemis I are lunar-focused and may help 

NASA address Strategic Knowledge Gaps to inform 

research strategies and prioritize technology development of 

human and robotic exploration. 

Other missions will be testing innovative propulsion 

technologies, studying space weather, analyzing the effects 

of radiation on organisms, and providing high-resolution 

imagery of Earth and the Moon. 

The NEA Scout CubeSat payload is integrated into its dispenser 

prior to the Artemis I flight.

30

Payload berth locations on the Orion stage adapter.
ARTEMIS I SECONDARY PAYLOADS

The Artemis I test flight includes objectives such as testing SLS performance, Orion's heat shield at lunar re-entry velocities, testing systems in deep space, 

exercising countdown and mission operations, and deploying CubeSat payloads in deep space.

31

The Jacobs team at NASA Kennedy installing the last of 10 CubeSats in the SLS rocket’s Orion stage adapter. BioSentinel, the final CubeSat to be loaded, 

will study how radiation affects living organisms in deep space. 
The CubeSats will be deployed after Orion separates and 

is a safe distance away. Each payload will be ejected with 

a spring mechanism from dispensers installed on the Orion 

ARTEMIS I SECONDARY PAYLOADS

32

stage adapter. Artemis I manifested payloads are listed 

below with their provider, area of exploration, and a brief 

summary:

Payload Developer(s) Sponsor Destination Mission

ArgoMoon Argotec Agenzia Spaziale 

Italiana

Geocentric 

orbit with high 

eccentricity and 

apogee close to 

the Moon

Photograph the ICPS, CubeSat 

deployment, the Earth and Moon 

using HD cameras and advanced 

imaging software 

BioSentinel NASA Ames, NASA 

Johnson, Loma Linda 

University Medical Center, 

University of Saskatchewan

NASA Advanced 

Exploration Systems 

(AES)

Heliocentric orbit 

via lunar flyby

Use yeast as a biosensor to 

evaluate the effects of ambient 

space radiation on DNA

CubeSat to Study Solar 

Particles (CuSP)

Southwest Research 

Institute, NASA Goddard

NASA Science Mission 

Directorate (SMD)

Deep space Study the sources and 

acceleration mechanisms of solar 

and interplanetary particles in 

near-Earth orbit

EQUilibriUm Lunar-Earth 

point 6U Spacecraft 

(EQUULEUS)

University of Tokyo Japanese Aerospace 

Exploration Agency

(JAXA)

Earth-Moon L2 

point

Demonstrate trajectory control 

techniques within the Sun-EarthMoon region and image Earth’s 

plasmasphere

Lunar IceCube Morehead State 

University, NASA JPL, 

NASA Goddard, BUSEK

NASA Next Space 

Technologies for 

Exploration Partnerships 

(NextSTEP)

Lunar orbit Search for water (and other 

volatiles) in ice, liquid, and vapor 

states using infrared spectrometer

Lunar-Polar Hydrogen 

Mapper (LunaH-Map)

Arizona State University NASA SMD Lunar orbit Perform neutron spectroscopy 

to characterize abundance of 

hydrogen in permanently shaded 

craters

LunIR Lockheed Martin Space 

Systems

NASA NextSTEP Heliocentric orbit 

via lunar flyby

Use a miniature high-temperature 

Mid-Wave Infrared (MWIR) sensor 

to characterize the lunar surface

Near Earth Asteroid 

(NEA) Scout

NASA Marshall NASA AES NEA within ~1.0 

astronomical unit 

(AU) of Earth

Detect target NEA, perform 

reconnaissance and close 

proximity imaging 

Outstanding MOon 

exploration Technologies 

demonstrated by Nano 

Semi-Hard Impactor 

(OMOTENASHI)

Institute of Space and 

Astronautical Science 

(ISAS)/JAXA

JAXA Lunar surface Develop world’s smallest lunar 

lander and observe lunar radiation 

environment

Team Miles Miles Space, LLC NASA Cube Quest 

Challenge, sponsored by 

NASA Space Technology 

Mission Directorate's 

Centennial Challenges 

Deep space Demonstrate propulsion using 

plasma thrusters; compete in 

NASA’s Deep Space Derby
ARTEMIS I SECONDARY PAYLOADS

For Artemis I, several “bus stops” were defined to provide 

payload developers with reference points when deciding 

when to deploy from the vehicle. For example, bus stop 1 is 

the first opportunity to deploy after Orion has separated and 

the ICPS has completed its mission operations. Bus stop 

33

1 also coincides with the entrance to the second Van Allen 

Belt. Bus stop 2 is about one hour past the Van Allen Belts 

to reduce radiation exposure to the CubeSats. Bus stop 3 

is equidistant between the Earth and Moon. Some payloads 

are deploying between bus stops.

Artemis I 

CubeSat Mission Estimated 

Deployment Time Mission Orbit Mission 

Duration Disposal

ArgoMoon

Perform proximity operations with the ICPS 

post-disposal; take external imagery of Earth 

and Moon by testing an advanced software 

imaging recognition system with highdefinition cameras

L + ~ 3 hrs. + 40 min. Geocentric 180 days

Heliocentric

orbit

CuSP

Study solar and interplanetary particles 

supporting space weather research by 

determining proton radiation levels during 

Solar Energetic Particle (SEP) events and 

identifying suprathermal properties that could 

help predict geomagnetic storms

L + ~ 8 hrs. + 3 min. Heliocentric 75 days

Heliocentric

orbit

LunaH-Map

Research to understand the quantity of 

hydrogen-bearing materials in cold traps in 

permanently shaded craters of the Moon’s 

South Pole

L + ~ 5 hrs. + 33 min. Lunar 601 days 

(1.6 years)

Lunar 

surface

LunIR

Perform a lunar flyby using a miniature 

high-temperature Mid-Wave Infrared 

(MWIR) sensor collecting spectroscopy and 

thermography data to address questions 

related to surface characterization, remote 

sensing, and site selection for future missions

L + ~ 6 hrs. + 3 min. Lunar flyby 30 days

Heliocentric

orbit

BioSentinel Contains a yeast radiation biosensor that will 

measure effects of space radiation on DNA

L + ~ 3 hrs. + 40 min. Lunar flyby 1 year

Heliocentric 

orbit

Lunar 

IceCube

Search for water in ice, liquid, and vapor 

forms as well as other lunar volatiles using a 

compact infrared spectrometer

L + ~ 3 hrs. + 40 min. Lunar < 2 years

Lunar 

surface

NEA Scout

Equipped with a solar sail to rendezvous with 

an asteroid, gather detailed imagery, and 

observe the asteroid’s position in space

L + ~ 5 hrs. + 10 min.

Earth and lunar flybys, targeting 

cislunar escape, enabling 

rendezvous with near-Earth 

asteroid

2.5 years

Heliocentric

orbit

OMOTENASHI

Land on the lunar surface to demonstrate 

the feasibility of the hardware for distributed 

cooperative exploration systems 

L + ~ 3 hrs. + 40 min. Lunar 5 days

Lunar 

surface

EQUULEUS

Fly to a libration orbit around the Earth-Moon 

L2 point and demonstrate trajectory control 

techniques within the Sun-Earth-Moon region

L + ~ 3 hrs. + 40 min. Lunar 270 days

Heliocentric 

orbit

Team Miles

Fly autonomously using a sophisticated 

onboard computer system with propulsion 

supplied by evolutionary plasma thrusters

L + ~ 7 hrs. + 3 min. Heliocentric 1 year max.

Heliocentric

orbit
THE 

ELEMENTS 

OF SLS

Each major element of SLS – the 

core stage, RS-25 engines, solid 

rocket boosters, ICPS, Launch 

vehicle stage adapter, and Orion 

stage adapter – serves a unique 

purpose. Each element is built and 

tested by a prime contractor working 

with numerous subcontractor 

suppliers. As part of the national 

strategic infrastructure, SLS is 

built by skilled American engineers 

and technicians at small and large 

contractor locations across the 

United States.

THE ELEMENTS OF SLS

34
THE ELEMENTS OF SLS

CORE STAGE

Core Stage

35

The SLS core stage is the tallest rocket 

stage NASA has ever built. It measures 

approximately 212 ft. (64.6 m) tall and 

27.6 ft. (8.4 m) in diameter (excluding 

thermal protection system foam and 

flanges). Its fully fueled weight, excluding 

engines, is 2.4 million lbs. (1,088 t). 

The SLS core stage contains four RS-25 

engines, their liquid hydrogen and liquid 

oxygen propellant supply, and the 

avionics and software that control SLS 

operation and flight until the core stage 

separates from the ICPS. It is literally the 

core of SLS, supporting other stages, 

spacecraft, and payloads atop its uppermost section and serving as the attach 

point for the two solid rocket boosters. 

The core stage is designed to operate for 

the entire roughly 480-second launch from ground to Earth 

orbit, reaching speeds of nearly Mach 23 and more than 

530,000 ft. (161.5 km) in altitude before it separates from 

the ICPS, Orion stage adapter, and Orion spacecraft. 

The core stage is made up of 10 major barrel sections, four 

dome sections, and seven rings. Each cylindrical barrel 

section consists of eight aluminum panels which vary in 

length and height depending on the section. Those panels 

are friction-stir welded or bolted vertically and horizontally 

to form the five major sections of the core stage:

– Engine section.

– Liquid hydrogen tank.

– Intertank.

– Liquid oxygen tank.

– Forward skirt.

The intertank is the lone bolted section to provide added 

strength to carry booster loads. 

The core stage is a major new development for the SLS 

Program, while other key elements, such as the RS-25 

engines, solid rocket booster structures, and ICPS have 

previous spaceflight experience. 

A key goal of the SLS design was to reuse space shuttle 

components or design within shuttle heritage experience 

where possible. For example, the core stage has the same 

diameter as the shuttle external tank and the propellant 

feedlines, and fill and drain ducts were sized around 

heritage joints and existing valves. 

Beginning at the bottom, or aft end, of the stage, the engine 

section houses four RS-25 main engines, the engine thrust 

structure, propellant ducts, various avionics systems, engine 

thrust vector control systems, and serves as the aft attach 

point for the two solid rocket boosters. 

The SLS core stage, the tallest rocket stage NASA has ever built, is lowered 

between the Artemis I boosters in the Vehicle Assembly Building.
THE ELEMENTS OF SLS

CORE STAGE

36

The engine section consists of a single barrel section and is 

27.6 ft. (8.4 m) in diameter, 22.5 ft. (6.9 m) tall, and consists 

of welded aluminum isogrid panels. An aerodynamic boat 

tail fairing at the bottom channels airflow and protects the 

engines from extreme temperatures during launch.

The liquid hydrogen fuel tank is 27.6 ft. (8.4 m) in diameter 

and 130 ft. (39.7 m) tall. It consists of five welded barrel 

sections each 22 ft. (6.7 m) tall and two end domes. The 

aft end of the liquid hydrogen tank includes four liquid 

hydrogen feedlines to the RS-25 engines. The tank has a 

capacity of 537,000 gal. (2 million L) of liquid hydrogen. 

The SLS core stage is comprised of 10 barrel sections, four dome sections, and seven rings as shown in this illustration of the core stage major components.
THE ELEMENTS OF SLS

CORE STAGE

The SLS Artemis I engine section, left, and liquid hydrogen tank, right, at Michoud prior to integration.

The intertank separates the upper hemispherical dome 

of the liquid hydrogen tank from the lower hemispherical 

dome of the liquid oxygen tank and serves as the forward 

attach point for the boosters. The intertank measures 27.6 

ft. (8.4 m) in diameter and 21.8 ft. (6.7 m) tall. It contains 

a thrust structure to carry loads imparted from the solid 

rocket boosters during ascent. The intertank also contains 

several avionics components, including two rear-facing 

cameras and interfaces to the liquid hydrogen and liquid 

oxygen tanks.

The liquid oxygen tank is 27.6 ft. (8.4 m) in diameter and 

51 ft. (15.6 m) tall. It consits of two 15.6-ft. (4.8 m) barrel 

sections of isogrid aluminum panels and two domes. 

Liquid oxygen is fed to the engine section and engines 

through a pair of “downcomer” ducts that exit the intertank 

on opposite sides and run down the core stage. The liquid 

oxygen tank has a capacity of 196,000 gal. (741,941 L). 

The thermal protection system on the tank minimizes 

boiloff of the -297 degrees Fahrenheit (-182.8 Celsius) 

liquid oxygen. Gaseous oxygen is vented overboard. 

37

The SLS Artemis I intertank at Michoud, prior to integration between the 

propellant tanks, has forward attach points for the two solid rocket boosters.
THE ELEMENTS OF SLS

CORE STAGE

The forward skirt is located at the top of the core stage. It 

connects the core stage to the Integrated Spacecraft/Payload 

Element. The aluminum isogrid structure is 27.6 ft. (8.4 m) in 

diameter and 10.4 ft. (3.2 m) tall. It houses the majority of the 

vehicle’s avionics and has connections to launch pad utility 

umbilicals, the vehicle stabilization system that helps secure 

SLS to the mobile launcher, access doors, vent system, 

pressurant lines, and antennas.

The main propulsion system in the core stage consists of the 

ducts, valves, and other equipment that supply and control 

the flow of liquid hydrogen and liquid oxygen propellants, as 

well as gaseous helium and nitrogen pressurants for valve 

actuation and line/volume purges. To accomplish those 

functions, the main propulsion system has four subsystems: 

– Liquid oxygen.

– Liquid hydrogen.

– Pressurization.

– Pneumatics supplied by ground systems prior to launch.

Major drivers in the design of the main propulsion system 

included the main propellant tank configuration, main 

engine configuration, reliability and affordability, mission 

requirements, and component mounting. For instance, the 

main propulsion system flow rates and interfaces were 

designed around the RS-25 configuration and the need to 

supply propellants to the engines under temperature and 

pressure conditions required by the engines. The orientation 

of the engine hydrogen and oxygen feedlines in the engine 

section determined the feed system layout for the main 

propulsion system.

The liquid oxygen tank being manufactured for the Artemis I flight at Michoud.

The core stage forward skirt contains the flight computers for the Block 1 

SLS rocket.

Connecting feedlines and other external components to the fully assembled 

Artemis I core stage at Michoud.

38
THE ELEMENTS OF SLS

CORE STAGE MANUFACTURING, TEST, 

AND CHECKOUT

The SLS core stage is manufactured at Michoud, where 

the Saturn rocket stages used during the Apollo Program 

and the space shuttle’s external tanks were manufactured. 

Boeing, as the prime contractor for the SLS core stage, is 

responsible for the design, manufacturing, and testing of 

the stage.

Manufacturing, Test, and Checkout

Hydraulic cylinders applied millions of pounds of force to the liquid oxygen 

tank test article, completing 20 tests until it failed, providing engineers with 

valuable data on the tank’s structural capabilities.

A significant development campaign preceded and ran 

concurrently with manufacturing of flight core stage 

components. Hundreds of metal “coupons” followed by 

test panels were welded at Marshall to develop the frictionstir welding process used to manufacture the core stage 

components at Michoud. 

Full-size core stage barrel sections and tanks were welded 

using production tools at Michoud. Those included 

production of full-size flight-like structural test articles for the 

engine section, liquid hydrogen tank, intertank, and liquid 

oxygen tank. 

The test version of the SLS liquid hydrogen tank withstood more than 260 

percent of expected flight loads over five hours before it buckled, then 

ruptured, giving engineers real-world data to reinforce computer models.

These were heavily instrumented with a range of sensors 

and installed in new test stands and fixtures at Marshall. 

They were subjected to flight loads created by hydraulic 

actuators applying millions of pounds of force to verify 

predicted performance and establish a margin of safety. 

The core stage structural tests, combined with testing 

of the SLS upper stage and adapters, was the largest 

structural test campaign at Marshall since tests conducted 

for the Space Shuttle Program more than 30 years ago. 

During the test campaign, five structural test articles 

underwent 199 separate test cases, and more than 421 

gigabytes of data were collected to verify data from 

computer models used to design the rocket. 

39
THE ELEMENTS OF SLS

CORE STAGE MANUFACTURING, TEST, 

AND CHECKOUT

Likewise, avionics and flight software, the “brains” of SLS, 

were developed, tested, and virtually flown thousands of 

times at Marshall's Integrated Avionics and Software and 

Systems Integration laboratories before the flight hardware 

and software were installed in the Artemis I core stage.

In addition, Artemis I core stage suppliers tested individual 

components before shipping to Michoud. Once at Michoud, 

Boeing tested the components and functions before 

installing them on the core stage. The completed stage 

underwent basic electrical and pneumatic testing before 

shipment to Stennis for the Green Run test campaign. 

“Green run” describes the first operational test of a new 

component. 

At Stennis, teams from Boeing, SLS, and Stennis used the 

Green Run test series of progressively more flight-like tests 

to activate stage systems, culminating in a hot fire of the 

engines that simulated launch and flight of the Artemis I 

core stage. 

Beginning in early 2020, the Artemis I core stage was 

installed in the B-2 test stand, used previously to support 

Saturn and shuttle propulsion tests. During the year it was 

subjected to a series of nine major Green Run tests: 

– Modal (vibration).

– Core stage avionics power on and checkout.

– Safing checks (how to shut down all core stage 

systems in case of an anomaly).

– Main propulsion system (stage propellant valves and 

ducts) and RS-25 leak checks and functional tests. 

– Hydraulic and thrust vector control (engine steering) 

checkout.

– Simulated countdown.

– Countdown and wet dress rehearsal (full stage 

operation, including flowing propellants to the engines 

for chilldown).

– Countdown and hot fire (limited duration test up to 

thrust vector control gimbal).

– Countdown and hot fire (full test of the stage including 

engines in flight-like operation).

At the end of testing, the stage was inspected and 

refurbished before shipping to Kennedy onboard NASA’s 

barge Pegasus.

40

Eight major "Green Run" tests at Stennis of the Artemis I core stage and RS-25 engines culminated in a full-duration hot firing, the largest test of liquid-fueled 

engines since the Apollo Program.
– There are 562 cables in the core stage. The largest 

number – 231 – are located in the engine section.

– There are 45 mi. of cabling in the core stage and 

more than 18 mi. in the engine section alone.

– There are 775 independent sensors that have wire 

routing to them.

– There are approximately 100,000 clamps and ties 

securing wires and cables throughout the core stage.

– The liquid hydrogen tank shrinks about 

6 in. (15.24 cm) in length and 1 in. (2.54 cm) 

in diameter when filled with cryogenic fuel.

– The liquid oxygen tank shrinks approximately 1.5 in. 

(3.81 cm) in length and 0.5 in. (1.27 cm) in diameter 

when filled with cryogenic propellant.

– To compensate for those changes, everything that 

attaches to them – ducts, vent lines, systems tunnel, 

brackets, etc. – must be connected by accordion-like 

bellows sections, slotted joints, telescoping sections, 

or ball joint hinges.

– Roughly 14,500 fasteners need to be drilled and filled 

in the intertank.

– The flight computer uses the same class 

microprocessor as the original Macintosh PowerBook 

G3. This is somewhere between a Pentium II and 

Pentium III. However, the operating system is much 

more sophisticated. 

– Each flight computer is rated to operate over a 

temperature range of -11 to 97.7 degrees Fahrenheit 

(-24 to 36.5 degrees Celsius).

THE ELEMENTS OF SLS

CORE STAGE FUN FACTS

Core Stage Fun Facts

41
THE ELEMENTS OF SLS

RS-25 ENGINES

RS-25 Engines

Four RS-25 engines power SLS for its eightminute climb to Earth orbit, together with a 

pair of solid rocket boosters that operate for 

the first two minutes of ascent. The RS-25 is 

formerly known as the Space Shuttle Main 

Engine (SSME). It flew successfully on 135 

space shuttle missions. 

The RS-25s have accumulated more than 

3,000 starts and one million seconds of 

ground and flight hot-fire experience. The 

RS-25, manufactured by Aerojet Rocketdyne, 

is the most efficient rocket engine in its class, 

allowing heavier payloads to be carried 

without increasing the rocket's size.

The RS-25 is a staged-combustion cycle 

engine that produces approximately 500,000 

lbs. of thrust. Each engine has an onboard 

The RS-25s have been upgraded with new controllers that were hot-fire 

42 tested prior to the Artemis I flight.

computer that automatically controls start and shutdown, 

thrust ranging from 65 percent to 109 percent, propellant 

mixture ratio, and engine health. 

During ascent, the engines are gimballed through two planes 

by hydraulic actuators to produce vehicle pitch, yaw, and roll. 

Several key design features that contribute to the RS-25’s 

high performance:

– Its cyrogenic liquid hydrogen and liquid oxygen 

propellants, which are more efficient than

hydrocarbon engines.

– Its staged-combustion operating cycle, in which 

propellants are burned twice, first in preburners then 

in the main combustion chamber, and its two highpressure turbopumps (liquid oxygen and liquid hydrogen) 

fed by two low-pressure pumps, creating higher main 

combustion chamber pressures.

It was that power, efficiency, and reliability – as well as the 

knowledge and experience base – that led to selection of 

the RS-25 for SLS. Each RS-25 is roughly 14 ft. (4.3 m) 

tall, 8 ft. (2.4 m) in diameter, and weighs approximately 

7,750 lbs. (3.5 t). Unlike the space shuttle, SLS will not 

reuse its RS-25s as the core stage size, as well as altitude 

and speed at MECO, make recovery impractical without 

significant sacrifice in payload-carrying capability. SLS is 

designed to launch the most ambitious space exploration 

missions and requires maximum performance.
THE ELEMENTS OF SLS

RS-25 ENGINES

The first four SLS missions will be powered by 14 flight-proven 

engines and two new engines assembled from shuttle-era engine 

components. Upgrades to the engines include development of 

new engine controllers and software and the addition of nozzle 

insulation to protect them from booster exhaust due to the 

engine and booster nozzles being located roughly in the same 

plane. New RS-25 engines now in manufacturing will be available 

for the fifth and subsequent missions.

The operations of the SLS RS-25s differs from operations during 

the Space Shuttle Program. Each shuttle mission used three 

engines, while each SLS mission uses four. Shuttles routinely 

operated with SSMEs throttled to 104.5 percent, or roughly 

491,150 lbs. (2,185 kN) of thrust. Each SLS engine will operate 

at 109 percent thrust – approximately 512,300 lbs. (2,279 kN) 

maximum thrust in a vacuum. 

The RS-25 uses a staged-combustion engine cycle that burns 

liquid hydrogen and liquid oxygen propellants at very high 

pressure. These engines operate in temperature extremes from 

-423 degrees Fahrenheit (-253 degrees Celsius) to 6,000 degrees 

Fahrenheit (3,316 degrees Celsius) and at pressures exceeding 

7,000 psi (48,263 kPa). The engine was certified by ground 

testing during the shuttle program to operate at the higher thrust, 

though it was never used operationally. 

With SLS, the RS-25 will experience several additional 

differences in performance requirements and operating 

environments. The SLS engine compartment will be colder 

because it is located directly below the liquid hydrogen fuel tank 

instead of the separate arrangement of the shuttle orbiter and 

external tank. The SLS engines will face higher liquid oxygen 

inlet pressures due to the higher position of the liquid oxygen 

tank relative to the engines as compared to the shuttle and 

external tank.

The Artemis I RS-25 liquid fuel engines operated successfully as part 

of the core stage Green Run hot fire test at Stennis in early 2021.

43

Artemis engine serial numbers and their position in the core stage 

relative to the boosters.
THE ELEMENTS OF SLS

RS-25 MANUFACTURING, TEST, 

AND CHECKOUT

In addition, the engine nozzles will also be subjected to a hotter 

launch pad environment due to their location closer to the SLS 

booster exhaust nozzles compared to a location farther above 

the booster exhaust nozzles on the space shuttle. Operationally, 

pre-launch engine conditioning will be different because of those 

environments, and the engine throttling and gimballing profile 

during ascent will be different due to vehicle acceleration and 

trajectory profile.

The SLS engines start in a staggered fashion: engine 1, 

engine 3, engine 4, then engine 2, approximately six seconds 

before booster ignition at T-0 and will follow this thrust profile:

– Engines start about 6 seconds prior to booster ignition.

– Engines reach 100 percent of rated power level about one 

second before booster ignition.

– Engines throttled to 109 percent rated power level at 

booster ignition (T-0).

– At T + 55 seconds, engines can be throttled down to lessen 

stress on the rocket during maximum dynamic pressure 

(max Q).

– At T + 81 seconds engines throttle back up to 109 

percent rated power level.

– At T + 123 seconds engines throttle down to 85 

percent rated power level (booster separation 

“bolt bucket” to reduce stress on attach struts 

and frangible bolts).

– At T + 132 seconds engines throttle back up to 

109 percent rated power level following booster 

separation.

– At T + 421 seconds engines throttle back as 

needed to reduce acceleration forces (max g 

level).

– At T + 476 seconds engines throttle back to 67 

percent rated power level.

– At T + 483 seconds, MECO.

The Artemis II RS-25 engines are designated as 

backups for the Artemis I engines. Engines 2047, 

2059, 2062, and 2063 have completed modification 

and are ready for flight if needed.

44

Flight engines are processed by Aerojet Rocketdyne at NASA 

Stennis. The company also supports engine integration into the 

core stage at Michoud, engine testing at Stennis and vehicle 

integration and launch at Kennedy.

Because of differences in SLS requirements and operating 

environment, the SLS Program conducted a series of “adaptation” 

firing tests from 2015 to 2019 at Stennis with a pair of existing 

ground test RS-25s. Testing also included running the engines at 

113 percent thrust to demonstrate new-production engines can 

run safely at 111 percent in case of a contingency. 

The series also included Green Run testing of all 16 new engine 

controllers, as well as testing of new parts manufactured with new 

techniques aimed at restarting engine production. A total of 32 

tests amassed nearly 15,000 seconds of hot fire time.

The 14 previously flown engines do not require certification firing 

tests because they are flight-proven and certified to operate at 

109 percent thrust. The Stennis test stand was also used to Green 

Run test the two new engines built from shuttle components.

Manufacturing, Test, and Checkout

RS-25 engine and controller hot fire testing at Stennis. 
THE ELEMENTS OF SLS

RS-25 FLIGHT HISTORY

Engines installed on the Artemis I core stage are serial 

numbers 2045, 2056, 2058, and 2060. All were reconfigured 

for SLS and accepted for flight without additional hot fire 

testing, having flown previously. All meet the SLS engine life 

requirements of four starts and 1,700 seconds operation time 

remaining. All four RS-25s slated for Artemis I have a rich 

history in NASA’s Space Shuttle Program flying to low-Earth 

orbit. They are veterans of these successful space shuttle 

missions:

Flight History of Artemis I RS-25 Engines

Engine 2045: STS - 89, 95, 92, 102, 105, 110, 113, 121, 

118, 127, 131, 135

– STS-89, Endeavour, flew in 1998, 

the eighth Shuttle-Mir docking.

– STS-95, Discovery, flew in 1998, 

Sen. John Glenn’s flight.

– STS-92, Discovery, flew in 2000, ISS assembly flight, 

Zenith Z1 Truss, pressurized mating adapter (PMA-3), 

and was the 100th space shuttle flight.

– STS-102, Discovery, flew in 2001, ISS assembly flight, 

first use of Multi-Purpose Logistics Module (MPLM), 

Leonardo.

– STS-105, Discovery, flew in 2001, ISS assembly flight, 

second flight of Leonardo.

– STS-110, Atlantis, flew in 2002, ISS assembly flight, 

S0 Truss segment, Mobile Transporter.

– STS-113, Endeavour, flew in 2002, ISS assembly flight, 

P1 Truss.

– STS-121, Discovery, flew in 2006, ISS utilization 

mission, only launch on Independence Day, 

MPLM Leonardo.

– STS-118, Endeavour, flew in 2007, ISS assembly flight, 

starboard S5 truss, External Stowage Platform 3, final 

Spacehab logistics module flight.

– STS-127, Endeavour, flew in 2009, ISS assembly flight, 

JEM/Kibo Exposed Facility, record for most humans in 

space at the same time in same vehicle (13) and tied 

record of 13 people in space at one time (13).

– STS-131: Discovery, flew in 2010, ISS flight, MPLM.

– STS-135: Atlantis, flew in 2011, ISS utilization flight, 

MPLM, last shuttle mission.

45

Engine 2056: STS - 104, 109, 114, 121

– STS-104, Atlantis, flew in 2001, ISS assembly, installed 

Quest joint airlock module.

– STS-109, Columbia, flew in 2001, Hubble Space 

Telescope servicing mission.

– STS-114, Discovery, flew in 2005, ISS assembly flight, 

first mission since Columbia accident.

– STS-121, Discovery, flew in 2006, ISS logistics mission, 

Leonardo MPLM to Unity.

Engine 2058: STS - 116, 120, 124, 119, 129, 133

– STS-116, Discovery, flew 2006, ISS assembly flight, 

P5 truss.

– STS-120, Discovery, flew in 2007, ISS assembly flight, 

delivered Harmony module.

– STS-124, Discovery, flew in 2008, ISS assembly flight, 

delivered JEM/Kibo.

– STS-119, Discovery, flew in 2009, ISS assembly flight, 

starboard Integrated Truss Segment, solar arrays, 

batteries.

– STS-129, Atlantis, flew in 2009, ISS assembly flight, 

2 ExPRESS logistics carriers.

– STS-133, Discovery, flew in 2011, ISS assembly flight, 

Permanent MPLM/Leonardo, 3rd ExPRESS carrier, 

Robonaut, last flight of Discovery.

Engine 2060: STS - 127, 131, 135

– STS-127, Endeavour, flew in 2009, ISS assembly flight, 

Kibo module.

– STS-131, Discovery, flew in 2010, ISS flight, MPLM.

– STS-135, Atlantis, flew in 2011, ISS utilization flight, 

MPLM, last shuttle mission.
THE ELEMENTS OF SLS

RS-25 FUN FACTS

– The thrust provided by the SLS RS-25 engines could keep 

eight Boeing 747s aloft.

– The RS-25 is so powerful that it could power 846,591 mi. 

of residential streetlights – a street long enough to go to the 

Moon and back, then circle the Earth 15 times.

– Four RS-25 engines push the SLS rocket 73 times faster 

than an Indianapolis 500 race car travels.

– The RS-25 could provide twice the power needed to move 

all 10 existing Nimitz-class aircraft carriers at 30 knots.

– The RS-25 generates about 20 percent more thrust at sea 

level than comparable kerosene engines using the same 

amount of hydrocarbon fuels.

– The RS-25 exhaust is clean, superheated water vapor.

– Each turbine blade powering the RS-25’s high-pressure fuel 

turbopump produces more horsepower than a Corvette 

ZR1’s 638 horsepower, and its airfoil is the size of a quarter.

– In the RS-25, coolant travels through the main combustion 

chamber in two milliseconds, increasing its temperature by 

400 degrees Fahrenheit (204 degrees Celsius).

– Pressure within the RS-25 is equivalent to an ocean depth 

of three miles – about the same distance where Titanic lies 

below the surface of the Atlantic Ocean.

– Together, the SLS’s four RS-25 engines gobble propellant 

at the rate of 1,500 gal. (5,678 L) per second during their 

eight minutes of operation – more than enough to drain an 

Olympic-size swimming pool in one second.

– Hot gases exit the RS-25’s nozzle at 9,600 mph (15,450 

km/h) – 13 times the speed of sound, or fast enough to go 

from Los Angeles to New York City in 15 minutes.

– While the RS-25 is about the same size and weight as 

the two turbojet engines on an F-15 fighter, it generates 

eight times more thrust, which it achieves in less than five 

seconds, operating between -400 degrees Fahrenheit (-240 

degrees Celsius) and 6,000 degrees Fahrenheit (3,316 

degrees Celsius).

RS-25 Fun Facts

46
THE ELEMENTS OF SLS

SOLID ROCKET BOOSTERS

Solid Rocket Boosters

47

A pair of solid rocket boosters attached to 

the core stage supply more than 75 percent 

of total SLS thrust for the first two minutes 

of flight, operating with the four RS-25 

main engines. Based on the space shuttle 

solid rocket boosters, the SLS boosters are 

the largest, most powerful solid propellant 

boosters ever built for flight. Each SLS 

booster is 177 ft. (54.1 m) tall, 12 ft. (3.7 m) in 

diameter, and weighs 1.6 million lbs. (726 t) 

when filled with solid propellant. 

The propellant on the SLS Block 1 rocket 

boosters consists of PBAN, ammonium 

perchlorate, and aluminum powder. Standing 

17 stories tall and burning approximately 5.5 

tons (5 t) of propellant each second, each 

booster generates more thrust than 14 fourengine jumbo commercial airliners.

The SLS booster is based on three decades of knowledge 

and experience gained with the space shuttle booster 

with several design, process, and testing improvements 

for greater performance, safety, and affordability. Shuttleheritage hardware transferred to the SLS Program for early 

flights includes forward structures, metal cases, aft skirts, 

and thrust vector control elements. 

Close-up view of the throat plug break up and expulsion from the nozzle 

during ignition of the Qualification Motor 2 full-scale test firing in Utah.

The major difference between the shuttle and SLS boosters 

is the addition of a fifth solid propellant segment to the 

four-segment shuttle booster, allowing SLS to send more 

weight to TLI than the shuttle lofted to low-Earth orbit. The 

larger SLS motor burns about three seconds longer and has 

more than 200,000 lbs. additional thrust. Other new design 

features of the SLS booster include:

– New manufacturing processes.

– New nozzle design three inches wider than the shuttle 

nozzle to support increased thrust.

– Modified propellant formulation with lowered burn rate.

– New grain design with 12-fin forward segment.

– New asbestos-free insulation and liner configuration.

– New avionics.

– Improved nondestructive evaluation processes.

– Aft booster attach rings moved 20 ft. (6 m) aft from the 

space shuttle external tank location to allow them to 

attach to the core stage engine section rather than the 

liquid hydrogen tank.

The SLS booster is optimized for a single use, to launch 

heavier payloads and reduce operational costs associated 

with the reusable booster used during the Space Shuttle 

Program. To that end, parachutes and other recovery 

features have been removed from the SLS booster. Deletion 

of the recovery systems translated into approximately 2,000 

lbs. (0.9 t) additional payload to TLI, the maneuver that 

sends Orion to the Moon.

Each SLS solid rocket booster has three major assemblies: 

forward skirt, motor, and aft.

The forward skirt assembly includes the nose cap, frustum 

with four solid fuel booster separation motors, and forward 

skirt. The forward skirt houses booster avionics, the flight 

termination system, and the core stage attach support 

posts that carry most of the static and flight loads for the 

SLS stack.
THE ELEMENTS OF SLS

SOLID ROCKET BOOSTERS

The motor assembly has five segments, each with two case 

segments filled with rubbery propellant. Beginning from the 

aft, or rear, end of the booster, the segments are: 

– Aft.

– Center aft.

– Center center.

– Center forward.

– Forward.

The forward segment contains the igniter that fires the 

length of the hollow motor segments to ignite all segments 

simultaneously. The segments, once ignited, burn from the 

inside out until all propellant is consumed. 

The forward assemblies for the SLS solid rocket boosters include 

aerodynamic nose cones, frustums, and forward skirts containing avionics.

48

The forward attach struts are also located on the forward 

segment. The aft motor segment is attached to an ablative 

exhaust nozzle that can be gimballed to steer the rocket. It 

contains the aft core stage attach struts.

The aft skirt assembly on each booster consists of the aft 

skirt, the thrust vector control system for the booster, and 

four solid booster separation motors. The thrust vector 

control system gimbals the exhaust nozzle and steers the 

vehicle. The boosters provide 90 percent of vehicle steering 

for the first two minutes of flight.

In addition to the booster motor, Northrop Grumman, lead 

booster contractor, also produces the booster separation 

motors used to push the boosters away from SLS at motor 

burnout. Each booster has four separation motors in the 

nose and four on the aft skirt for a total of 16 on the vehicle. 

After the RS-25 engines start, booster ignition occurs at 

T-0 seconds and the vehicle lifts off the mobile launcher 

platform and begins its ascent. The propellant grain design 

inside the motor segments – the shape of the hole running 

the length of the motor – is designed to provide a maximum 

3.6 million lbs. (16,014 kN) thrust for roughly 25 seconds, 

ramp down to about 2.8 million lbs. (12,455 kN) thrust as 

SLS passes through max Q, and then ramp up to about 3.3 

million lbs. (14,679 kN) of thrust before beginning to tail off 

about 90 seconds into flight. 

The solid rocket boosters’ aft assembly includes the aft skirts with thrust 

vector control system inside that helps steer SLS during ascent. The entire 

weight of the SLS rocket goes through the aft skirt structures.
THE ELEMENTS OF SLS

SOLID ROCKET BOOSTERS

Booster separation occurs at about 2 minutes 12 seconds, 

142,000 ft. (43.3 km) at Mach 4.3. In order to separate from 

the vehicle, pyrotechnically activated separation bolts on 

the booster attach struts fire and four solid fuel separation 

motors at the top and bottom of each booster fire to push 

49

the empty boosters safely away from the core stage. Each 

booster separation motor generates about 20,000 lbs. (89 

kN) of thrust. The boosters splash down in the Atlantic 

Ocean roughly 5.5 minutes after launch.

The five-segment SLS solid rocket boosters generate 7.2 million lbs. (32,027 kN) of thrust – more than 75 percent of the rocket’s total thrust for the first two 

minutes of flight.
THE ELEMENTS OF SLS

SOLID ROCKET BOOSTERS 

MANUFACTURING, TEST, AND CHECKOUT

SLS boosters are manufactured by Northrop Grumman in 

Utah and at Kennedy. In Utah, motor segment cases are 

lined with insulation and then filled with solid propellant. 

Each segment undergoes a rigorous nondestructive 

inspection process to confirm it is ready for flight. Motor 

segments are shipped by rail to Kennedy prior to flight.

Northrop Grumman builds the aft and forward skirt 

assemblies at several facilities near the launch site in Florida. 

Previously flown structures are refurbished at the Hangar AF 

complex at the Cape Canaveral Space Force Station, then 

moved to the Booster Fabrication Facility (BFF) at Kennedy. 

There, Northrop Grumman installs avionics, thrust vector 

control systems, booster separation motors, and thermal 

protection. These systems are thoroughly tested at the BFF 

before delivery to the EGS program along with the motor 

segments and aft exit cones delivered from Utah. 

Manufacturing, Test, and Checkout

EGS then builds the overall aft assembly in the RPSF at 

Kennedy by attaching the aft motor segment to the aft 

skirt assembly and adding the lower core stage attach 

struts. That aft assembly is moved to the Vehicle Assembly 

Building and is the first element lowered onto the mobile 

launcher to begin the rocket assembly.

The rest of the motor segments are then stacked and 

pinned on top of each other: center aft, center center, center 

forward, and finally the forward motor segment. A forward 

assembly, consisting of a forward skirt and nose cone, is 

then attached to each booster. After booster stacking, the 

core stage is lowered between the boosters. Each booster is 

mated to the SLS core stage by braces on the forward and 

aft booster segments. On the mobile launcher, the booster 

aft skirts carry the entire load, or weight, of the SLS and 

Orion stack.

50

Artemis I booster motors travel by rail, left, from prime contractor Northrop Grumman facilities in Utah to Kennedy. Right, motor segments are offloaded, 

inspected, and stored at Kennedy’s RPSF before transport to the Vehicle Assembly Building for stacking on the mobile launcher.
THE ELEMENTS OF SLS

SOLID ROCKET BOOSTERS 

MANUFACTURING, TEST, AND CHECKOUT

The SLS five-segment solid rocket motor is the result of 

experience of the shuttle booster motor as well as extensive 

post-shuttle development. Northrop Grumman conducted 

numerous tests on subscale motors to evaluate specific 

components or materials such as the motor case insulation 

and nozzle materials and configuration. The company also 

conducted a series of full-scale development motor tests 

and qualification motor tests. 

Three development motor tests in 2009, 2010, and 2011 

were used to evaluate the five-segment design and various 

other design changes. The Development Motor-1 test was 

the first to evaluate thrust, roll control, acoustics, and motor 

vibrations using 650 data channels. The Development 

Motor-2 test motor was chilled to 40 degrees Fahrenheit (4.4 

degrees Celsius) to verify performance of 53 test objectives 

using more than 760 data channels. Development Motor-3

was the most heavily instrumented motor to date, with more 

than 970 sensors collecting data for 37 test objectives 

after the motor was heated to 90 degrees Fahrenheit (32.2 

degrees Celsius). 

Subsequently, Northrop Grumman conducted two full-scale 

qualification motor tests at its Utah test facilities in 2015 

and 2016. Test motors were again heated to 90 degrees 

Fahrenheit (32.2 degrees Celsius) and cooled to 40 degrees 

Fahrenheit (4.4 degrees Celsius), respectively. Engineers 

collected additional data on motor upgrades such as the 

new insulation and booster case liner, redesigned exhaust 

nozzle, etc. to support more than 100 test objectives. This 

is how solid rocket motor designs are determined to be 

ready for flight. Once these ground tests are complete, the 

manufacturing process is carefully controlled to ensure 

the flight boosters will perform as well as the ground test 

articles.

Boosters lead contractor Northrop Grumman and NASA hot-fired several full-scale solid rocket motors to help qualify them for the SLS Program.

Birds-eye view of the Artemis I solid rocket boosters, the first element to be 

stacked on the mobile launcher in the Vehicle Assembly Building, awaiting 

the core stage. 51
THE ELEMENTS OF SLS

SOLID ROCKET BOOSTERS FLIGHT HISTORY

Several missions’ worth of space shuttle booster hardware 

was transferred to the SLS Program for its early missions, 

while Northrop Grumman restarted booster manufacturing, 

Flight History of the SLS Booster Structures

52

incorporating several new features. The charts below 

summarize the shuttle flight history behind each of the 

Artemis I booster components.

Artemis I booster aft assemblies ready for stacking in Kennedy Vehicle 

Assembly Building.
THE ELEMENTS OF SLS

SOLID ROCKET BOOSTERS FUN FACTS

– The SLS solid rocket boosters are 177 ft. (53.9 m) tall, 

taller than the Statue of Liberty from base to torch.

– Each booster is 12 ft. (3.6 m) in diameter.

– The boosters are the first element to be installed on the 

mobile launcher.

– The weight of the entire 5.75 million-lbs. (2,608 t) rocket 

rests on the booster aft skirts.

– Each booster weighs 1.6 million lbs. (726 t) when loaded 

with propellant.

– Each booster burns approximately 5.5 tons (5 t) of 

propellant a second. 

– Each booster generates 3.6 million lbs. of thrust, more 

thrust than 14 four-engine jumbo commercial airliners.

– During the first two minutes of flight, the boosters 

provide more than 75 percent of the total SLS thrust.

– During hot fire testing in the Utah desert, the booster 

motor burns so hot that sand hit by the nozzle exhaust 

turns to glass.

– The boosters operate for about 2 minutes 12 seconds 

and are then jettisoned into the Atlantic Ocean.

– Once all the propellant in the solid rocket boosters has 

burned, 16 small solid rocket motors, called booster 

separation motors, in the forward and aft sections of 

each booster, fire simultaneously to safely push the 

boosters away from the SLS rocket.

– If their heat energy were converted to electric power, the 

two solid rocket boosters firing for two minutes would 

produce 2.3 million KWh of power, enough to supply 

power to more than 92,000 homes for a full day.

SLS Solid Rocket Boosters Fun Facts

53

The completed Artemis I boosters are shown stacked on the mobile 

launcher in the Vehicle Assembly Building at Kennedy Space Center before 

integrating the other elements of SLS and Orion.
THE ELEMENTS OF SLS

INTEGRATED SPACECRAFT/PAYLOAD ELEMENT

Integrated Spacecraft/Payload Element

54

The SLS Block I configuration will be 

used for NASA’s first three Artemis 

missions. The Integrated Spacecraft/

Payload Element for the SLS Block I 

crew configuration is located above 

the core stage and below the Orion 

spacecraft. It includes elements for 

in-space propulsion, adapters, and a 

separation system. 

On the Artemis I flight, the Integrated 

Spacecraft/Payload Element also 

includes a deployment system for 

secondary payloads. On Artemis I, the 

ICPS fires first to raise Orion’s orbit 

and then a second time to send Orion 

on a path to the Moon. The launch 

vehicle stage adapter partially encloses 

the ICPS and serves as an interface 

between the larger core stage below and the smaller Orion 

stage adapter above. The Orion stage adapter connects the 

ICPS to Orion.

Jacobs crews bolt the launch vehicle stage adapter to the SLS core stage 

in the Vehicle Assembly Building.
THE ELEMENTS OF SLS

INTERIM CRYOGENIC PROPULSION STAGE

The 45-ft. (13.7 m)-tall, 16.7-ft. (5.1 m)

-diameter ICPS is a modified Delta Cryogenic 

Second Stage, a proven upper stage used 

on ULA’s Delta IV family of launch vehicles. 

ULA builds the ICPS at its rocket factory 

in Decatur, Alabama. After completion, it’s 

shipped to ULA’s Delta Operations Center 

at Cape Canaveral Space Force Station on 

ULA's R/S Rocketship cargo ship for final 

checkout prior to stacking in the Vehicle 

Assembly Building.

Modifications to the Delta stage for the Block 

1 SLS missions include lengthening the 

liquid hydrogen tank by 18.4 in. (46.7 cm), 

adding a second hydrazine bottle for attitude 

control, a new navigation system, Orion 

and launch vehicle stage adapter electrical 

and mechanical interfaces, a modified 

Interim Cryogenic Propulsion Stage

liquid hydrogen vent and relief valve, an RL10 in-flight 

helium injector purge to support engine restart, and RL10 

qualification to SLS environments.

The stage is powered by liquid hydrogen and liquid oxygen, 

feeding a single Aerojet Rocketdyne RL10B-2 engine 

producing 24,750 lbs. (110 kN) of thrust. The RL10 has 

been in use more than 50 years to launch numerous military, 

government, and commercial satellites into orbit and send 

spacecraft to every planet in the solar system. 

APPROXIMATE TIMELINE OF ICPS EVENTS DURING THE ARTEMIS I FLIGHT

Major ICPS event Approximate time post-launch (T-0)

ICPS/core stage separation T-0 + 8 minutes and 30 seconds

ICPS coast to near apogee T-0 + 8 minutes and 20 seconds to 51 minutes

ICPS perigee raise burn T-0 + 50 minutes and 30 seconds to 51 minutes and 20 seconds

Parking orbit coast T-0 + 51 minutes to 1 hour and 36 minutes

ICPS TLI burn T-0 + 1 hour and 37 minutes to 1 hour and 55 minutes

Coast to Orion separation from ICPS T-0 + 1 hour and 55 minutes to 2 hours and 5 minutes

Post-separation coast T-0 + 2 hours and 5 minutes to 3 hours and 45 minutes

ICPS disposal maneuver to heliocentric orbit T-0 + 3 hours and 45 minutes to 3 hours and 48 minutes 

*Numbers based on 2021 mission analysis as this guide was in development and will vary based on season, launch date, and time. Numbers are 

approximated to meet security, export control, and proprietary requirements.

For the Artemis I mission, the ICPS will perform three burns: 

– A perigee burn to circularize Orion’s orbit.

– A TLI burn to push Orion out of Earth orbit to the Moon.

– A disposal burn after Orion separation to send ICPS 

into an orbit around the sun (heliocentric orbit).

55

The ICPS is a single-engine liquid hydrogen/liquid oxygen stage based on 

the Delta Cryogenic Second Stage from ULA that produces 24,750 lbs. 

(110 t) of thrust and performs the TLI burn to send Orion toward the Moon.
THE ELEMENTS OF SLS

LAUNCH VEHICLE STAGE ADAPTER

The cone-shaped launch vehicle stage 

adapter partially encloses the ICPS 

and provides the interface between the 

27.6-ft. (8.4 m)-diameter core stage 

and 16.7-ft. (5.1 m)-diameter ICPS. The 

adapter is 27.5 ft. (8.4 m) tall. Hatches in 

the adapter allow technicians access to 

the ICPS during processing at Kennedy. 

The launch vehicle stage adapter also 

protects avionics and electrical devices 

in the ICPS from extreme vibration and 

acoustic conditions during launch and 

ascent. 

A pneumatically actuated frangible joint 

assembly at the top of the launch vehicle 

stage adapter separates the ICPS, Orion 

stage adapter, and Orion from the core 

stage and launch vehicle stage adapter 

during ascent. 

Launch Vehicle Stage Adapter

56

Cameras inside the adapter provide engineers with data on 

its performance and location in space after the core stage 

and launch vehicle stage adapter separate from the ICPS 

and Orion. The launch vehicle stage adapter stays attached 

to the core stage and they are disposed of together in the 

Pacific Ocean. The launch vehicle stage adapter adapter partially encloses the ICPS and 

contains the pyrotechnic system to separate itself and the core stage from 

the ICPS and Orion.

Teledyne Brown Engineering manufactures the launch vehicle stage adapter 

at Marshall, where technicians manually apply spray-on insulation, which 

turns orange in sunlight.
THE ELEMENTS OF SLS

ORION STAGE ADAPTER

The highest SLS element in the SLS stack, the 

Orion stage adapter, connects the ICPS to the 

Orion spacecraft. The Orion stage adapter is 

18 ft. (5.5 m) in diameter, 5 ft. (1.5 m) tall, and is 

made of lightweight aluminum. 

The adapter contains a diaphragm that provides 

a barrier to prevent gases, such as hydrogen, 

generated during launch from entering Orion. For 

Artemis I, the Orion stage adapter will also carry 

small secondary payloads, called CubeSats. 

SLS provided a comprehensive secondary 

payload deployment system for the CubeSats, 

including mounting brackets for commercialoff-the-shelf dispensers, cable harnesses, a 

vibration isolation system, and an avionics unit. 

Following separation from Orion, when the 

uncrewed spacecraft is a safe distance away, 

the avionics unit in the Orion stage adapter 

Orion Stage Adapter

57

secondary payload deployment system will begin sending the 

signals to release the payloads at regular intervals (to ensure no 

re-contact) at pre-selected times. Following secondary payload 

deployment, the Orion stage adapter remains attached to the 

ICPS and enters a heliocentric disposal trajectory.

The completed Orion stage adapter after delivery from Marshall to 

Kennedy. The brackets to hold the dispensers for the CubeSat payloads and avionics unit are visible.

The ring-shaped Orion stage adapter is filled with 10 shoebox-sized 

CubeSats that will deploy when the ICPS separates from Orion on its 

way to the Moon.
THE ELEMENTS OF SLS

ISPE MANUFACTURING, TEST, AND CHECKOUT

The ICPS is manufactured by ULA. Its RL10 engine is 

manufactured by Aerojet Rocketdyne in its West Palm 

Beach, Florida facility.

Teledyne Brown Engineering manufactures the launch 

vehicle stage adapter using self-reacting friction-stir welding 

tools at the Advanced Weld Facility at Marshall. The adapter 

consists of two cones and two ring sections. Technicians 

first vertically weld panels to make the bottom cone. 

Then they weld panels to make the upper cone. Finally, a 

circumferential weld joins the two cones. Welded rings go on 

the top and bottom of the cone. 

The first launch vehicle stage adapter manufactured at 

Marshall’s Advanced Weld Facility was used as a test 

article along with the ICPS, Orion stage adapter, and a core 

stage simulator for a series of structural tests conducted 

at Marshall. Engineers subjected the stack of test articles 

to loads up to 40 percent greater than they will experience 

during ascent and flight. The results of this Integrated 

Structural Test were used to validate computer models 

simulating how the Integrated Spacecraft/Payload Element 

will behave in flight.

The Orion stage adapter is manufactured in-house at 

Marshall. Technicians in the Advanced Weld Facility have 

made three adapters in support of Artemis I. The first 

adapter was used in the Integrated Structural Test described 

above. It was later shipped to Lockheed Martin in Denver, 

where engineers used it for additional structural testing. 

The second adapter flew on Exploration Flight Test-1 in 

December 2014, connecting the Orion spacecraft to a ULA 

Delta IV launch vehicle for Orion’s initial test flight. The third 

adapter is the Artemis I flight article.

The Integrated Structural Test series at Marshall was the 

beginning of the largest structural testing campaign since the 

Space Shuttle Program. The test qualified the launch vehicle 

stage adapter, ICPS, Orion stage adapter, and frangible joint 

assembly that separates the ICPS and Orion from SLS. The 

integrated stack, which included an Orion simulator, was 

subjected to forces up to 40 percent higher than anticipated 

flight loads. Approximately 50 test cases collected about 

1,900 channels of data including temperature, deflection, 

torsion, compression, and other factors.

Manufacturing, Test, and Checkout

58

The Integrated Structural Test at Marshall included applying loads 40 

percent greater than expected during launch to test versions of the launch 

vehicle stage adapter, frangible joint assembly, ICPS, Orion stage adapter, 

and a mass simulator for Orion.

The launch vehicle stage adapter structural test article for the Integrated 

Structural Test was manufactured and tested at Marshall.
THE ELEMENTS OF SLS

SLS AVIONICS AND SOFTWARE

SLS Avionics and Software

The SLS core stage, engines, boosters, and ICPS all have 

computers and software that monitor and control their 

functions. The avionics in the engines, boosters, and ICPS 

are connected to the flight avionics in the core stage. The 

core stage flight computers use data from the distributed 

avionics systems from the boosters, engines, and 

throughout the core stage to control the rocket and carry 

out its mission. It also transmits vehicle performance data 

to controllers on the ground on Artemis I and to the crew in 

Orion on later missions.

Core stage avionics and flight software serve as the “brains” 

of the rocket. They contain and execute the commands 

to prepare and launch SLS, route data and commands to 

the stage, distribute power, produce navigation and flight 

control data, produce range safety tracking data, execute 

flight termination commands, produce motion imagery, 

provide telemetry to ground systems, synchronize and 

process data, monitor stage conditions, and receive/

execute flight safety commands.

Core stage avionics consist of four main subsystems:

– Flight control.

– Telemetry.

– Flight safety. 

– Electrical power. 

Avionics equipment is distributed among the forward skirt, 

intertank, and engine section in the core stage (the solid 

rocket boosters and ICPS also contain avionics).

Three flight computers and four power, data, telemetry, and 

navigation systems are located in the forward skirt. Each of 

the three flight computers uses three microprocessors. Each 

flight computer executes the same software for redundancy. 

The intertank houses 26 avionics systems for power, 

power distribution, data receiving/handling, telemetry, and 

vehicle camera control. The engine section contains 10 

avionics systems related to engine monitoring and vehicle 

navigation.

SLS flight software provides the flight and pre-flight 

software functions necessary for on-pad pre-launch 

procedures, launch, and ascent of SLS up to ICPS 

separation. The software was developed at Marshall.

The flight control system, led by three redundant flight 

computers, monitors the rocket’s condition, senses 

vehicle motion, generates navigation and control data, 

actuates main propulsion system valves, monitors the main 

propulsion system and engine controls, and routes flightcritical commands to engine thrust vector control systems, 

and controllers. The flight computers have 256 MB of RAM 

each.

The core stage telemetry system includes radio and 

ethernet communications with the ground, telemetry 

control, engineering and development flight instrumentation, 

and a motion imagery system.

The flight safety system provides range tracking data and 

controls the rocket’s self-destruct function located in the 

core stage and boosters.

The avionics power system distributes ground power, stores 

ground power for flight, and provides data to ground 

control centers.

59

Avionics throughout the elements of SLS monitor the rocket's health and 

control the flight.
MANAGEMENT ROLES 

AND FACILITIES

MANAGEMENT ROLES AND FACILITIES

60

SLS is managed and supported 

by NASA Headquarters in 

Washington, D.C., and multiple 

NASA field centers across 

the nation. The Exploration 

Systems Development 

Mission Directorate and Space 

Operations Mission Directorate 

oversee NASA’s human 

exploration programs in and 

beyond low-Earth orbit.
MANAGEMENT ROLES AND FACILITIES

MARSHALL SPACE FLIGHT CENTER

Marshall Space Flight Center

Marshall is home to the SLS Program Office and manages 

all areas of the program, including planning, procurement, 

development, testing, evaluation, production, and operation 

of the integrated vehicle. MSFC also developed and tested 

the flight software in-house. 

The program office is also supported by Resident 

Management Offices (RMOs) at Stennis Space Center, 

which conducts engine and stage Green Run testing; 

and at Kennedy Space Center, responsible for integration 

and launch. The RMOs coordinate SLS technical and 

operations expertise with the EGS Program.

61

Several Marshall facilities support SLS. Building 4693 is a 

twin-tower open structure built to perform structural testing 

on a liquid hydrogen tank test article. Measuring 221 ft. 

(67.3 m) tall, the tower reuses the foundation of a former 

Saturn rocket test stand. For structural testing on the SLS 

liquid hydrogen tank structural test article, 38 hydraulic 

pistons were used to impart simulated flight loads on the 

tank, while more than 3,900 sensors measured temperature, 

deflection, strain, pressure, sound, and imagery.

Building 4697 is an L-shaped open tower structure built to 

test the liquid oxygen tank structural test article. Soaring 

90 ft. (27.4 m) tall, the stand used 24 hydraulic pistons and 

more than 2,700 sensors to conduct 32 structural loads 

tests on the liquid oxygen tank structural test article. 

Special test equipment consisting of two open-structure 

towers were built in Building 4619 at Marshall to test core 

stage engine section and intertank structural test articles. 

Unique Test Facilities

The engine section tower measured 58 ft. (17.6 m) tall 

and the intertank tower measured 62 ft. (18.9 m) high. 

The engine section was subjected to 49 tests monitored 

by approximately 3,000 sensors. The intertank underwent 

42 tests monitored by approximately 3,000 sensors.

The Systems Integration Lab/Systems Integration Test 

Facility allows engineers to test software with hardware 

in the loop. This allows them to fully simulate the 

integration of systems in virtual space prior to hardware 

manufacturing and test flight. Engineers in the lab also 

create and run end-to-end simulation environments 

in support of the entire project life cycle, including 

requirements development and analysis, as well as 

early prototyping, testing, and verification. These unique 

capabilities ensure that software and hardware integrate 

seamlessly before rocket manufacturing and assembly. 

The Systems Integration Lab/Systems Integration Test Facility at Marshall is a full-scale mockup of flight-like avionics systems for the solid rocket boosters 

and core stage where engineers can test hardware and software integration prior to manufacture and flight.
MANAGEMENT ROLES AND FACILITIES

MARSHALL SPACE FLIGHT CENTER

The SLS Engineering Support Center (SESC), located in the

Huntsville Operations Support Center, allows engineers 

specializing in the engines, boosters, core stage, avionics, 

and upper stage to monitor the rocket’s propulsion and other 

systems during the countdown and flight. The teams in the 

SESC leading up to and during launch analyze and monitor 

temperatures, pressures, flow rates, stresses, and other types 

of telemetry from the rocket. SESC teams also produce flash 

reports for the Mission Management Team and report on and 

archive data for additional study in the weeks and months 

after launch. 

The SESC will support the LCC at Kennedy and the Flight 

Operations Directorate team located at the Mission Control 

Center at Johnson, performing in-depth analyses to help 

mission officials. 

The SESC facility, which once served a similar purpose for 

both the Apollo and Space Shuttle Programs, has been 

updated with new communication and data equipment 

that provide greater data throughput and more voice 

communications channels. It also has the capability to reach 

out to SLS contractor organizations around the nation for 

additional expertise and attention to any issues. The SESC is 

staffed by a team from the SLS Program, MSFC engineering, 

and SLS contractors.

The Natural Environments Branch at Marshall characterizes 

terrestrial, space, and planetary natural environments in 

support of the SLS Program and other projects and programs 

across NASA. The Natural Environments Branch has been 

Supporting Launch Operations

collecting detailed atmospheric data from the Earth’s surface 

and aloft at Kennedy since the Apollo Program. The branch 

collects this data and develops weather databases for use 

by NASA and commercial customers to support spacecraft 

and launch vehicle programs in three major areas: system 

requirements design, verification and validation, and mission 

operations.

In addition to supporting SLS design and verification, the 

branch supports mission operations by generating complete 

atmospheric profiles for use in verifying SLS trajectory and 

loads constraints due to atmospheric wind conditions prior 

to launch.

For SLS and the Artemis I mission, the Natural Environments 

Branch also supports the Day of Launch Initialization Load 

Update. This update collects and uses day-of-launch 

atmospheric winds and temperature to design and verify the 

SLS flight profile in order to minimize loads (stresses) on the 

vehicle to ensure a safe flight. 

On launch day, Kennedy and the Space Launch Delta 45 

Eastern Range update weather data. The Marshall Natural 

Environments Branch uses the data to generate a profile 

of wind, temperature, density, and pressure at 100-ft. 

(30.5 m) intervals from the surface to 600,000 ft. (183 km). 

Johnson inputs that data into software to generate a flight 

guidance profile that is then validated by independent 

teams at Johnson and Marshall before sending those files 

to the launch team at Kennedy for upload onto SLS flight 

computers to translate into engine throttling and steering 

commands that minimize wind stresses on the rocket.

Marshall's SESC is networked to Kennedy, Johnson, and contractor locations nationwide to provide engineering support for SLS testing and launch operations.

62
MANAGEMENT ROLES AND FACILITIES

MARSHALL SPACE FLIGHT CENTER

On launch day, Marshall's Natural Environments Branch measures temperature, wind speeds, and more at Kennedy to provide data inputs critical to definiing 

final flight trajectories.

63
MANAGEMENT ROLES AND FACILITIES

MICHOUD ASSEMBLY FACILITY

Michoud Assembly Facility

The SLS core stage was manufactured, assembled, and checked 

out at Michoud before shipping to Stennis for stage Green Run 

testing and shipment to Kennedy for vehicle integration. For more 

than half a century, Michoud has been America's rocket factory, the 

nation’s premier site for manufacturing, assembling, and checkout 

of large-scale space structures and systems. 

The government-owned manufacturing facility is one of the 

largest in the world, with 43 acres of manufacturing space under 

one roof — a space large enough to contain more than 31 football 

fields. Marshall manages Michoud; commercial firms and NASA 

contractors use several areas of the facility. Michoud employs 

several key new manufacturing technologies and approaches to 

produce the SLS core stage:

– Lean manufacturing approaches with a production footprint 

about half what was used to manufacture the space shuttle’s 

external tank. The SLS production workforce is also less than 

half of the external tank program headcount.

– Friction stir welding, providing stronger, lighter structures 

produced without welding defects. Core stage welded barrel 

sections used to assemble the rocket tanks are produced in 

less than half the time compared to space shuttle external 

tank production.

– Horizontal, single cell, robotically controlled application of 

spray-on foam insulation.

– Spun dome technology for dome caps, reducing complexity 

associated with gore panels.

Michoud is managed by Marshall and is the world's premier rocket 

factory and one of the largest manufacturing facilities in the world, 

with 43 acres under one roof.

The Vertical Assembly Center at Michoud is one of the world's 

largest welding tools and is used to execute vertical friction-stir 

welds of the SLS core stage liquid hydrogen tank.

64
MANAGEMENT ROLES AND FACILITIES

MICHOUD ASSEMBLY FACILITY

At Michoud, six major multi-function assembly/welding tools developed for SLS have resulted in a greater than 80 percent 

reduction in tooling from shuttle external tank production. This reduced tooling also minimizes hardware handling, reducing 

complex hardware lifting operations by more than 70 percent. 

The new tools in NASA’s rocket factory include:

– The Circumferential Dome Weld Tool, which performs circumferential friction-stir welds in the production of 

dome assemblies for the SLS core stage cryogenic tanks.

– The Gore Weld Tool performs vertical conventional friction stir welds in the production of gore assemblies for the SLS 

core stage tanks. (Gores are preformed aluminum alloy dome segments that are welded together to make the dome).

– The Circumferential Dome Weld and Gore Weld tools are special tooling for the Enhanced Robotic Weld Tool, which is 

used to make dome components for SLS.

– The Vertical Weld Center is a friction-stir-weld tool for wet and dry structures on the SLS core stage. It welds barrel 

panels together to produce whole barrels for the two pressurized tanks, the intertank, the forward skirt, and the engine 

section. It stands about three stories tall and weighs 150 tons (136 t).

– The Segmented Ring Tool uses a friction-stir-weld process to produce segmented support rings for the SLS core stage; 

the rings connect and provide stiffness between domes and barrels.

– The Vertical Assembly Center is where domes, rings, and barrels are joined to complete the tanks or dry structure 

assemblies. The tool also performs nondestructive evaluation on the completed welds. This tool measures 170 ft. 

(51.8 m) tall and 78 ft. (23.7 m) wide and is one of the world's largest welding tools.

The gore weld tool at Michoud is used to weld domes for the SLS core stage propellant tanks.

65
MANAGEMENT ROLES AND FACILITIES

STENNIS SPACE CENTER

Stennis Space Center

As the nation’s largest propulsion test site, Stennis plays a 

major role in testing for SLS, just as it did for Saturn rockets 

and space shuttle vehicles.

The Fred Haise Test Stand was used to conduct multiple 

tests of RS-25 developmental engines to ensure the 

modified flight engines will operate to SLS requirements and 

environments. It was also used to Green Run test two new 

RS-25 engines, as well as new engine controllers for all 16 

shuttle engines transferred from the Space Shuttle Program. 

The hot fire tests for the new engines and controllers also 

were conducted on Stennis’s Fred Haise Test Stand. In 

2021, NASA began using the stand to test RS-25 engines 

with newly designed parts made with advanced technology, 

such as additive manufacturing or 3D printing, for a new 

generation of engines for the fifth SLS flight and beyond. 

Newer engines will have the same high performance as the 

upgraded engines used for early Artemis missions, but with 

anticipated manufacturing cost savings of more than 30 

percent.

The Fred Haise Test Stand is a single-position, vertical-firing 

facility, which means that it can accommodate one rocket 

engine at a time and that engines are fired in an upright 

position with thrust directed downward. The stand was 

constructed from December 1964 to February 1967. The 

first test of an RS-25 rocket engine was conducted on the 

Fred Haise Test Stand on January 9, 2015. On April 4, 2019, 

Stennis completed testing of all 16 RS-25 main engines that 

will help launch the first four SLS missions.

NASA Stennis provides unique facilities for testing SLS RS-25 engines and 

controllers. The B Complex, foreground, was used for Green Run testing 

the SLS core stage.

66
MANAGEMENT ROLES AND FACILITIES

STENNIS SPACE CENTER

The stand extends 58 ft. (17.7 m) below ground and 158 ft. 

(48.2 m) above ground. It can withstand rocket engine thrust 

up to about 1.1 million lbs. (4,893 kN) of force; the thrust 

limit is known as the maximum dynamic load.

The B Test Complex at Stennis features a dual-position, 

vertical-firing test stand designated B-1/B-2, built in the 

1960s. The B-1 Test Stand is designed for single-engine 

testing. The B-2 Test Stand is built to accommodate 

rocket stage testing. The B-2 Test Stand underwent major 

refurbishment and modifica¬tion to conduct the SLS Artemis 

I core stage Green Run test series to ready the stage for 

integration and flight. 

The B-1/B-2 Test Stand is anchored in the ground with 144 

ft. (43.9 m) of steel and concrete. As constructed, the soft 

core of the B-2 Test Stand was about 290 ft. (88.4 m) tall. 

The new steel superstructure added for testing SLS extends 

that height to almost 350 ft. (106.7 m), ranking the stand as 

one of the tallest structures in the state of Mississippi. 

Stennis test stands are linked by a 7.5-mile canal system 

used for transporting rocket stages and liquid propellants. 

Support facilities for Stennis test stands include a test 

67

control center for each complex; data acquisition facilities; 

a large High Pressure Gas Facility to supply pressurized 

nitrogen, helium, hydrogen, and air; an electrical generation 

plant that provides power for engine tests to avoid potential 

disruptions in the power grid; and a High-Pressure Industrial 

Water Facility that features large diesel pumps, as well as 

a new electric pump, and a 66 million gal. (249,837,178 L) 

reservoir.

The main derrick crane atop the B-2 Test Stand was 

extended 50 ft. (15.2 m) with an increased load rating of 195 

tons (177 t) to lift the SLS core stage, which is larger and 

heavier than the earlier Saturn V stages. More than 32,500 

5/32-inch holes drilled in the B-2 Test Stand flame deflector 

direct more than 240,000 gal. (908,499 L) of water a minute 

to cool engine exhaust during a test. Another 92,000 gal. 

(348,258 L) of water per minute is sprayed through 92 

nozzles to provide vibro-acoustic suppression protection to 

the core stage during testing. More than 100 water nozzles 

are arrayed across the test stand to provide a curtain of 

water over the length of the core stage and across the 

facility, if needed, to prevent damage in the event of a fire or 

cryogenic spill. 

NASA Stennis provides unique facilities for testing SLS RS-25 engines and controllers.
INDUSTRY

PARTNERS

INDUSTRY PARTNERS

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Truly America’s rocket, over the course of the SLS 

Program more than 1,100 companies from 48 states 

have contributed to designing, developing, 

manufacturing, testing, and supporting SLS, the 

rocket that will return NASA’s human spaceflight 

program to the Moon. Several prime contractors head 

up the manufacturing, test, and assembly of the major 

elements of SLS, but they in turn are supported by 

hundreds of smaller suppliers across the U.S.
INDUSTRY PARTNERS

AEROJET ROCKETDYNE

Aerojet Rocketdyne

Aerojet Rocketdyne is the prime contractor for the four 

powerful RS-25 engines used to help propel each SLS 

mission. The four liquid hydrogen/liquid oxygen-fed RS-25 

engines produce more than 2 million lbs. (8,896 kN) of 

thrust. The RS-25 contract is managed out of the company’s 

Canoga Park, California, facility, which is also where the 

majority of the design work and component fabrication 

takes place. 

Assembly and testing occur at the company’s facility 

located at Stennis. In addition to the RS-25 engines, 

the company also provides propulsion that will be used 

throughout the Artemis I mission. Aerojet Rocketdyne 

designs, manufactures, and tests the RL10 engine that 

propels the ICPS in West Palm Beach, Florida, and a suite 

of propulsion for the Orion spacecraft is manufactured in 

Redmond, Washington. The company’s subsidiary, ARDE, 

located in Carlstadt, New Jersey, builds the oxygen and 

nitrogen (nitrox) tank for the life support system on Orion 

and five composite overwrapped pressure vessels that store 

high-pressure helium to inflate Orion’s flotation system upon 

water landing.

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Industry partner Aerojet Rocketdyne, headquartered in Sacramento, California, supplies RS-25 engines for the SLS core stage and RL10 engines for the 

ICPS.
INDUSTRY PARTNERS

BOEING

Boeing

Boeing is the prime contractor for the design, development, 

test, and production of the SLS core stage and ICPS, as 

well as development of the flight avionics suite. Boeing built 

and tested the core stage for the Artemis I mission, and 

production for the Artemis II, III, and IV stages is underway, 

including the EUS, a more powerful in-space stage for 

NASA’s Block 1B and ultimate Block 2 variants.

The Boeing SLS Program is managed out of the company’s 

Space and Launch division in Huntsville, Alabama, and 

employs Boeing’s workforce in Huntsville, at Michoud, 

Kennedy, and at other Boeing sites and with suppliers 

across the country. The Boeing Exploration Launch Systems 

office supports NASA on strategy and policy for Space 

Exploration programs procured by Marshall.

Boeing is the prime contractor for the SLS core stage, manufactured at 

Michoud, and the ICPS, manufactured by ULA.

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INDUSTRY PARTNERS

NORTHROP GRUMMAN

Northrop Grumman

Northrop Grumman is the prime contractor for the design, 

development, testing, and production of the twin solid 

rocket boosters that provide more than 75 percent of 

initial thrust for SLS. Building off the knowledge and flightproven hardware from the Space Shuttle Program, the new 

five-segment design features enhanced technologies and 

incorporates 25 percent more propellant to make these 

the largest rocket boosters ever built for flight. Additionally, 

Northrop Grumman provides 16 booster separation motors, 

designed to push the spent solid rocket boosters away from 

the core stage, for each launch. 

The Northrop Grumman Northern Utah team manages the 

production and testing of the SLS solid rocket boosters, 

with teams at Kennedy and Huntsville, Alabama, overseeing 

various components and providing on-site support. 

Northrop Grumman also produces the launch abort motor 

and the attitude control motor for the Orion spacecraft’s 

Launch Abort System. The abort motor is manufactured 

and tested out of the company’s Promontory and Bacchus, 

Utah facilities, and work on the attitude control motor is 

based in Elkton, Maryland.

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Northrop Grumman manufactures the solid rocket boosters for SLS, as well two of the three the solid motors used in Orion's launch abort system.
INDUSTRY PARTNERS

TELEDYNE BROWN ENGINEERING

Teledyne Brown Engineering

Teledyne Brown Engineering, based in Huntsville, 

Alabama, has been a leader in innovative products, 

systems, integration, operation, and manufacturing 

for the space industry for more than 65 years. 

Teledyne Brown provides engineering, technical 

support, and hardware for the launch vehicle 

stage adapter. The launch vehicle stage adapter is 

manufactured using the friction-stir welding tools 

in the Advanced Weld Facility at Marshall. It is the 

largest piece of the current SLS configuration to be 

built at Marshall. In addition to the Artemis I adapter, 

Teledyne Brown Engineering also delivered the 

launch vehicle stage adapter structural test article in 

2016 for the Integrated Structural Test.

Teledyne Brown Engineering is the lead contractor for the launch vehicle stage adapter 

that has a pneumatically activated frangible joint that separates it and the core stage 

from the ICPS, Orion stage adapter, and Orion during flight.

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INDUSTRY PARTNERS

UNITED LAUNCH ALLIANCE

United Launch Alliance

ULA is working collaboratively with Boeing to 

develop the 5-m ICPS for Artemis I, II, and III. 

The ICPS stages are manufactured in ULA’s 

Decatur, Alabama, manufacturing facility. The 

ICPS stage is a modified version of the ULA 5-m 

Delta Cryogenic Second Stage, which has flown 

24 times with 100 percent mission success.

With more than a century of combined heritage, 

ULA is the nation’s most experienced and 

reliable launch service provider. ULA has 

successfully delivered more than 140 missions 

to orbit that aid meteorologists in tracking 

severe weather, unlock the mysteries of our solar 

system, provide critical capabilities for troops 

in the field, deliver cutting-edge commercial 

services, and enable GPS navigation.

ULA’s program management, engineering, test, 

and mission support functions are headquartered 

in Denver, Colorado. Manufacturing, assembly, 

and integration operations are located at 

Decatur, Alabama, and Harlingen, Texas. Launch 

operations are located at Cape Canaveral Space 

Force Station, Florida, and Vandenberg Space 

Force Base, California.

ULA supplies the ICPS, which is based on the Delta Cryogenic Second Stage, for the SLS 

Block 1 rocket. 

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ADDITIONAL 

RESOURCES

ADDITIONAL RESOURCES 

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UNDERSTANDING SLS: INFOGRAPHICS

Understanding SLS: Infographics

75

In addition to the Quick Facts in the front of this document, 

selected SLS infographics below will help you understand 

SLS and its unique capabilities to enable continuous, ongoing 

human exploration of the Moon through the Artemis program. 

Additional infographics describing SLS design, capabilities, 

testing, and more are available on the SLS web site at 

https://www.nasa.gov/exploration/systems/sls/multimedia/

infographics.html
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TABLE OF CONTENTS

ACRONYM LIST

ACRONYM DEFINITION

AES.................. Advanced Exploration Systems

BFF.................. Booster Fabrication Facility

EGS ................. Exploration Ground Systems

ESA.................. European Space Agency

EUS ................. Exploration Upper Stage

GSE ................. Ground Support Equipment

ICPS ................ Interim Cryogenic Propulsion Stage

ISS....................International Space Station

ITCO ................ Intergrated Test and Check Out

JAXA................ Japanese Aerospace Exploration Agency

LAS.................. Launch Abort System

LCC ................. Launch Control Center

LVSA................ Launch Vehicle Stage Adapter

Max Q.............. Maximum Dynamic Pressure

MECO.............. Main Engine Cutoff

MPLM.............. Multi-Purpose Logistics Module

OSA ................. Orion Stage Adapter

PBAN............... Polybutadiene Acrylonitrile

RPSF ............... Rotation, Processing, and Surge Facility

SESC ............... SLS Engineering Support Center

SLS.................. Space Launch System

SMD................. Science Mission Directorate

SSME............... Space Shuttle Main Engine

STS.................. Space Transporation System

TLI.................... Trans-Lunar Injection

ULA.................. United Launch Alliance

For more information about SLS, visit: 

http://www.nasa.gov/artemis

http://www.nasa.gov/sls 

http://www.twitter.com/NASA_SLS

http://www.facebook.com/NASASLS

http://www.instagram.com/exploreNASA

LINKS
NOTES
NOTES
National Aeronautics and Space Administration

George C. Marshall Space Flight Center

Huntsville, AL 35812

www.nasa.gov/marshall

www.nasa.gov

SLS-4071

NP-2022-08-65-MSFC