US-based Aerojet Rocketdyne has been contracted by Nasa to produce additional Space Launch System (SLS) RS-25 rocket engines.

According to the follow-on contract, the company will manufacture 18 additional SLS engines for future Artemis missions.

Valued at $1.79bn, the new contract includes labour for construction and testing the engines to manufacture required tools and necessary support for SLS flights.

The order is a modification of the contract that was awarded in November 2015 to recertify and build six new RS-25 engines.

It increases the contract value to approximately $3.5bn, which covers the delivery of 24 engines for six additional SLS flights. The period of performance runs until 30 September 2029.

Nasa Marshall Space Flight Centre Huntsville, Alabama, SLS program manager John Honeycutt said: “This contract allows Nasa to work with Aerojet Rocketdyne to build the rocket engines needed for future missions.

“The same reliable engines that launched more than 100 space shuttle missions have been modified to be even more powerful to launch the next astronauts who will set foot on the lunar surface during the Artemis missions.”

Each SLS rocket is powered by four RS-25 engines that produce two million pounds of thrust.

Aerojet Rocketdyne will perform work on the engines at its factory in Canoga Park, California, US. 

The cost of the engines has been lowered by 30%, leveraging advanced manufacturing techniques to modify certain rocket components.

The Artemis programme is part of the US’ broader moon to Mars exploration approach to land astronauts to the moon to explore and gain experience and send humans to Mars.

In October last year, Aerojet Rocketdyne signed Space Act Agreement with Nasa’s Marshall Space Flight Centre.