Aerojet Rocketdyne on Thursday test-fired its RS-25 rocket engine that will be used on the Space Launch System, the new heavy-lift rocket NASA has under development to power future manned missions to the moon and possibly to Mars.

The test at NASA’s Stennis Space Center in Mississippi was the sixth in a seven-test series that began in January.

Aerojet Rocketdyne makes the RS-25 engine at its Chatsworth campus. It is a modified version of the engines used on the space shuttle.

The Sacramento-area based company provided 16 of the engines to NASA for testing, enough for the first four missions using the Space Launch System rocket.

The Chatsworth facility is ramping up to manufacture more of the engines, which fit on the bottom of the core stage of the rocket.

The first test flight of the rocket is scheduled to take place before November 2018. The first manned mission is scheduled for 2021.