Seems simple once you think about it

Rico says his friend Tex passes along this one:

Sometimes it does take a rocket scientist!
Scientists at NASA built a gun (photo) specifically to launch standard four-pound dead chickens at the windshields of space shuttles, military jets, and airliners, all traveling at maximum velocity. The idea was to simulate the frequent incidents of collisions with airborne fowl to test the strength of the windshields.
British engineers heard about the gun, and were eager to test it on the windshields of their new high-speed trains. Arrangements were made, and a gun was sent to the British engineers. When the gun was fired, the engineers stood shocked as the chicken hurled out of the barrel, crashed into the shatterproof shield, smashed it to smithereens, blasted through the control console, snapped the engineer's back-rest in two, and embedded itself in the back wall of the cabin, like an arrow shot from a bow.
The horrified Brits sent NASA the disastrous results of the experiment, along with the designs of the windshield and begged the American scientists for suggestions.
NASA responded: "Defrost the chicken."