J-2X -- Back in the Saddle Again - A J-2X power pack assembly burns brightly during a hot fire test Nov. 27 at NASA's Stennis Space Center in Mississippi. Engineers pulled the assembly from the test stand in September to install additional instrumentation in the fuel turbopump. The test, which ran for 278 seconds, verified the newly installed strain gauges designed to measure the turbine structural strain when the turbopump is spinning at high speeds that vary between 25,000 and 30,000 rotations-per-minute. The J-2X engine -- built by Pratt & Whitney Rocketdyne of Canoga Park, Calif. -- will power the upper stage of NASA's Space Launch System, managed at the Marshall Space Flight Center in Huntsville, Ala. The new heavy-lift rocket system will launch the Orion spacecraft and enable humans to explore new destinations beyond low Earth orbit.