NASA orders 18 more engines for its Space Launch System megarocket

The four RS-25 rocket engines of NASA's Space Launch System rocket take center stage in this photo. NASA has ordered 18 new engines for its Artemis moon program.
The four RS-25 rocket engines of NASA's Space Launch System rocket take center stage in this photo. NASA has ordered 18 new engines for its Artemis moon program. (Image credit: NASA)

NASA has ordered 18 more rocket engines for its new Space Launch System megarocket for future Artemis moon missions. 

The new order, valued at $1.79 billion, calls for the California-based aerospace company Aerojet Rocketdyne to provide 18 RS-25 engines to power future SLS rockets. The agreement builds upon an existing deal between NASA and Aerojet for six SLS engines. This new order boosts the final contract's value to about $3.5 billion through 2029, NASA officials said. 

"This contract allows NASA to work with Aerojet Rocketdyne to build the rocket engines needed for future missions," NASA SLS program manager John Honeycutt at the agency's Marshall Space Flight Center in Huntsville, Alabama said in a statement.

Related: How NASA's Space Launch System will work (infographic)

Each SLS rocket will use four RS-25 rocket engines to launch its 212-foot (65-meter) core stage. The rocket will also use two strap-on solid rocket boosters and an upper stage to launch NASA's Orion crew capsule. The Artemis program will use SLS and Orion to return astronauts to the moon by 2024.

NASA currently has 16 of the engines (salvaged from the agency's now-retired space shuttle program) that will be used on the first four SLS rocket launches for Artemis missions 1 through 4. Those engines will cover Artemis flights through the program's first crewed moon landing (Artemis 3) and a follow-up flight. 

NASA's Artemis 1 mission is expected to launch in 2021. The engines for that flight are installed on an SLS core stage and awaiting a major test at NASA's Stennis Space Center in Mississippi. That work has been on hold since March due to the ongoing coronavirus pandemic.

The new agreement with Aerojet Rocketdyne will add another 24 SLS engines for the Artemis program, enough for another six flights. 

"We've already begun production on the first six new RS-25 engines," SLS engines manager Johnny Heflin said in the same statement. "Aerojet Rocketdyne has restarted the production lines, established a supplier base and is building engines using advanced techniques that reduce both the cost and time for manufacturing each engine."

The SLS rocket's four RS-25 engines provide a total of 2 million lbs. of thrust during launch to carry an Orion capsule into orbit. The engines left over from the space shuttle program have been overhauled with new computer controllers and upgraded to ensure they can handle the higher performance demands of an SLS launch, NASA officials have said.

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Tariq Malik

Tariq is the Editor-in-Chief of and joined the team in 2001, first as an intern and staff writer, and later as an editor. He covers human spaceflight, exploration and space science, as well as skywatching and entertainment. He became's Managing Editor in 2009 and Editor-in-Chief in 2019. Before joining, Tariq was a staff reporter for The Los Angeles Times covering education and city beats in La Habra, Fullerton and Huntington Beach. In October 2022, Tariq received the Harry Kolcum Award for excellence in space reporting from the National Space Club Florida Committee. He is also an Eagle Scout (yes, he has the Space Exploration merit badge) and went to Space Camp four times as a kid and a fifth time as an adult. He has journalism degrees from the University of Southern California and New York University. You can find Tariq at and as the co-host to the This Week In Space podcast with space historian Rod Pyle on the TWiT network. To see his latest project, you can follow Tariq on Twitter @tariqjmalik.

  • Anjisan63
    Awesome! At only $146 Million per rocket, I'm really looking forward to their One-Time use and disposal into the ocean after it flies once. What a DEAL for us US Taxpayers!
  • shellyhe
    I said it many months ago. the SLS rocket is enormously expensive with constant cost overruns and delays. Can't we trust our commercial partners by now? They have military contracts these days. I know that SpaceX flies their payloads regularly.

    NASA: Please don't order or build more engines or other parts anymore. Leave everything for the commercial guys. They will have the moon rockets up faster, safer and cheaper. Sell off the existing inventory. Please spend your money wiser. Please save the tax payers now and use that money for something that is needed today. We all know what that is.
  • Lovethrust
    Can’t wait for that monster to fly, it’s going to open up the outer solar system for large craft.
  • Ebonheart
    it's really time to move NASA contracts to Fixed-Price Structure. NASA isn't an endless pile of money.
  • Anjisan63
    I think should start adding these adjectives to any article that discusses rockets or rocket engines: Reusable / Disposable.

    So many countries end entities are now building reusable rockets. I think it would be awesome of to recognize this very distinctive difference in rocket functionality and the impact this functionality has on the overall costs.