MINOT AIR FORCE BASE, N.D. -- A B-52H Stratofortress fires up its engines on the flightline here before daybreak Jan. 30. The B-52's engines are being tested to measure the difference between JP-8 fuel, which the B-52 is accustomed to, and Fischer-Tropsch, a new synthetic fuel. The testing of synthetic fuel in cold weather is the last step in the certification process to help reduce Air Force dependence on imported fuel. With added wind chill, Minot Air Force Base experienced temperatures of minus 25 degrees on this day. (U.S. Air Force photo by Airman 1st Class Christopher Boitz)