HALO jumps are used to enter hostile territory undetected when threats to both Airmen and aircraft are expected.
3-D Printed Injector Roars to Life
A 3-D printed injector roars to life on a test stand at NASA's Marshall Space Flight Center in Huntsville, Ala. The injector fabricated with a technique called 3-D printing, or additive manufacturing, produced a record 20,000 pounds of thrust and was the largest rocket engine part of its kind tested by NASA to date. (NASA/MSFC) Read more at http://www.popsci.com/technology/article/2013-08/nasa-tests-largest-3-d-printed-rocket-part-ever