NASA fires up engines that will take the SLS to Mars
 

NASA has successfully tested four RS-25 engines, which will power the Space Launch System (SLS), for the sixth time at the Stennis Space Center in Mississippi. The space agency fired them up for 535 seconds and collected data to determine what need...

http://www.engadget.com/2015/08/13/s...cid%3Drss_semi