RS-25 roars to life during Jan. 9, 2015 test fire in Mississippi. Credit: NASA

The RS-25 engine, to be used for NASA’s Space Launch System rocket, was hot-fire tested Jan. 9 at the Stennis Space Center in Mississippi. Credit: NASA TV

#SLSFiredUp! RS-25 engine successfully completes first hot-fire test at @NASAStennis:

— NASA_SLS (@NASA_SLS) January 10, 2015

Heard about today’s successful hot fire test & want to know more about AR’s #RS25 engines that will power @NASA #SLS?

— Aerojet Rocketdyne (@AerojetRdyne) January 10, 2015