HUNTSVILLE, Ala. (AP) -- Young NASA engineers are testing a vintage rocket engine that was meant to blast the first U.S. lunar mission into Earth's orbit more than 40 years ago.

The agency conducted the last of 11 test firings Thursday on the heart of the engine, which was once part of the Apollo program's massive Saturn V (five) rocket.

The device shot out a huge plume of orange flame at NASA's Marshall Space Flight Center in Huntsville. The thundering roar could be heard for miles.

Officials hope to use technology from the Apollo program for the next generation of U.S. missions into space by the 2020s.

NASA engineer Nick Case is 27 years old, and he's impressed with the work done by engineers using slide rules and pencils in the 1960s.