Success! Engine for NASA's Space Launch System Megarocket Aces 3rd Test

The RS-25 rocket engine for NASA's future megarocket, the Space Launch System (SLS), was test-fired for about 8.5 minutes yesterday (July 25). The test, the third in a row for NASA, occurred at the agency's Stennis Space Center near Bay St. Louis, Mississippi. 

"In the heart of baseball season, NASA completed its equivalent of a clean inning, successfully testing the third RS-25 flight controller for use on the new Space Launch System (SLS) deep space rocket," NASA officials wrote in a statement. The test lasted about 500 seconds and was conducted on the A-1 Test Stand at Stennis, they added. [Watch:How NASA's Space Launch System Will Fly]

"With this latest test, NASA continues to set the stage for deep-space exploration missions, achieving another milestone toward launch of the first integrated flight of SLS and the Orion spacecraft, known as Exploration Mission-1," NASA officials said. "SLS will be powered at launch by four RS-25 engines, firing simultaneously to provide 2 million pounds [900,000 kilograms] of thrust and working in conjunction with a pair of solid rocket boosters to produce up to 8 million [3.6 million kg] pounds of thrust."

The four Aerojet Rocketdyne RS-25 engines that will be used on Exploration Mission-1 (EM-1) are former space shuttle engines, but the flight controllers that operate them will be new.

"The controller is the key modification to the engines and is characterized as the 'brain' that provides precision control of engine operation and internal health diagnostics, and allows communication between the RS-25 engine and the SLS," NASA officials said. "During launch and flight, the controller communicates with the SLS flight computers, receiving critical commands and returning engine health and status data." 

The first new RS-25 engine flight controller was tested in March, and a second test occurred in May. 

NASA is targeting a 2019 launch for EM-1. The mission will use an SLS rocket to launch an uncrewed Orion space capsule on a three-week trip around the moon. 

Editor's note: senior producer Steve Spaleta contributed to this story.

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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.