NEW ORLEANS — Three of four engines are now attached to the core of NASA's new Space Launch System, built in New Orleans and designed to launch the Artemis I mission to the moon.

The third Aerojet Rocketdyne RS-25 engine was attached without any problems, a Boeing Company spokesman said in an email Thursday. Engineers and technicians will now work to complete the installation process by connecting propulsion and electrical systems to the main rocket. 

Boeing is tasked with building the Space Launch System, sometimes referred to as the SLS. 

The SLS under construction at the Michoud Assembly Facility in New Orleans East is the backbone of NASA's plans for deep-space human exploration. According to Boeing it will be the only rocket capable of sending astronauts and heavy cargo to the moon on a single mission. 

Similar engines to the one installed Thursday have been used to launch 135 space shuttle missions. The newest models have been updated with new controllers and features. 

Here's a graphic showing how the SLS works: