Final element of NASA’s first SLS rocket arrives at Kennedy Space Center

The first SLS core stage was rolled into the Kennedy Space Center's Vehicle Assembly Building on April 29.
The first SLS core stage arrived at the Kennedy Space Center from the Stennis Space Center in Mississippi on April 28 | Image credit: NASA/Frank Michaux

The final element of NASA’s first heavy-lift Space Launch System rocket has arrived at the Kennedy Space Center for final integration ahead of its debut later this year… hopefully.

The first SLS core stage rolled off NASA’s Pegasus barge on April 29 for the short trip from the water’s edge to the Vehicle Assembly Building (VAB). At 68 meters long, the stage dwarfed everything around it except for its colossal building destination.

The VAB was the final stop before the launchpad for every Apollo and Space Shuttle mission ever launched. Standing at 160 meters tall, the building is steeped in history and after a decade of its high bays sitting idle since the retirement of the shuttle, a flurry of activity has returned.

As the SLS core underwent over a year of testing at NASA’s Stennis Space Center in Mississippi, teams at the Kennedy Space Center began stacking the rocket’s solid-fuel booster in one of the two VAB high bays in November 2020 atop the mobile launch platform.

The rocket’s two solid-fuel boosters will produce 6,5 million pounds of thrust burning for 120 seconds before separation. Derived from the four-segment Space Shuttle solid rocket boosters, each SLS booster is made up of five segments and a nose cone.

NASA SLS rocket is being prepared for the launch of Artemis 1.
Stacking of the Artemis I SLS boosters was completed in March | Image credit: NASA

The stacking of the two SLS boosters was successfully completed in March in preparation for the arrival of the core stage.

The SLS core stage is the largest and most powerful rocket stage ever produced. Powered by four RS-25 engines Aerojet Rocketdyne engines, the stage is designed to produce 1,6 million pounds of thrust and burn for eight minutes and 19 seconds. It also houses the rocket’s flight computers and much of the avionics need to control the rocket’s flight.

In addition to the boosters and core stage, the Artemis I mission hardware includes the Orion spacecraft and Interim Cryogenic Propulsion Stage.

Derived from the Delta Cryogenic Second Stage utilised by the United Launch Alliance Delta IV rockets, the ICPS is powered by an Aerojet Rocketdyne RL10B-2. The stage is only slated to be utilised for Artemis I, II and III. The more powerful Exploration Upper Stage being developed by Boeing will be utilised for Artemis IV onwards.

The Artemis 1 ICPS was the first element of the mission’s hardware to be delivered in November 2017. The stage was handed over to teams at the Kennedy Space Center during a ceremony in the Space Station Processing Facility.

The ICPS will be stacked atop the core stage with the Orion spacecraft completing the 111-meter rocket stack.

Orion is made up of a crew capsule and the European Service Module (ESM). The EMS is produced by Airbus under contract from the European Space Agency as a part of the agency’s involvement in NASA’s Artemis program.

The maiden flight of NASA's Orion spacecraft atop an SLS rocket is slated for late 2021.
The Orion spacecraft is made up of the crew capsule and the European Service Module | NASA/Radislav Sinyak

Acting as the Orion spacecraft’s power plant, the ESM provides propulsion, electrical power, thermal control and consumables like oxygen and water. The Artemis 1 ESM was fully assembled at Airbus Defence and Space’s factory in Bremen, Germany in October 2018 and delivered to the Kennedy Space Center a month later.

The Orion crew capsule is developed and built by Lockheed Martin. The capsule has a diameter of 5.03 meters, seats four and is capable of operating for just over 21 days.

Derived from a spacecraft destined for the cancelled Constellation program, work on Orion began in May 2011. The first uncrewed test flight of the capsule, Exploration Flight Test-1, was launched atop a Delta IV Heavy in 2014 without its service module.

Assembly of the Orion crew capsule for Artemis I, which included integration with the ESM, was completed in the Neil Armstrong Operations & Checkout Building at the Kennedy Space Center in January 2021.

Although it was cleared for launch, in November 2020 a malfunction with one of the crew capsule’s eight power and data units was discovered. Replacing the component would have required disassembling much of the spacecraft and would have delayed the launch by several months at least. However, as Artemis I will not carry a crew, NASA made the decision to utilise the spacecraft as is.

Following the completion of assembly and integration, the Artemis 1 Orion stack was moved to the Multi-Payload Processing Facility where it is currently being fueled. Once complete, the stack will be moved to the Launch Abort System Facility to be integrated with its launch abort tower, which will pull spacecraft away from the rocket in the event of a failure.

The maiden flight of NASA's SLS rocket and Orion spacecraft is currently slated for late 2021.
The Orion Launch Abort System is designed to pull the spacecraft away from the rocket in the event of a failure | NASA/Frank Michaux

The AA-2 Launch Abort System is designed and produced by Lockheed Martin under its Orion contract. The system is made up of a three-motor stack consisting of the abort and attitude control motors supplied by Northrop Grumman, and the jettison motor supplied by Aerojet Rocketdyne.

Each element of the AA-2 Launch Abort System has undergone several tests including aboard the Exploration Flight Test-1 in 2014 which was only equipped with the jettison motor.

A race to the launchpad

Despite delays and cost overruns that have mired both the development of the SLS rocket and the Orion spacecraft, NASA has remained optimistic that a late 2021 debut is possible.

During a Space Transportation Association webinar on April 27, then-Acting NASA Administrator Steve Jurczyk stated that a 2021 launch of Artemis I was challenging but nonetheless possible.

“If things go really, really well on integration of SLS and integrating Orion on the mobile launch platform and rolling out, we have a chance to launch by the end of the calendar year,” said Jurczyk.

President Biden’s recently confirmed NASA Administrator Bill Nelson also stated that a 2021 launch was possible however, he also suggested it may not.

“At the end of the year, perhaps early next year, you’re going to see the largest rocket ever launched,” Nelson said during his confirmation hearing in April.

Artemis 1 is slated to be the first integrated flight of NASA’s Orion spacecraft and SLS rocket. It will be launched from Pad 39B at the Kennedy Space Center on a 25-day trip around the Moon. The mission is expected to validate the system for the first crewed flight, Artemis II.

Andrew Parsonson is a space enthusiast and the founder of Rocket Rundown. He has worked as a journalist and blogger for various industries for over 5 years and has a passion for both fictional and real-life space travel. Currently, Andrew is the primary writer for Rocket Rundown as we look to expand our reach and credibility.