Wet countdown demonstration and flight readiness firing

The prelaunch tests for the Space Transportation System 1 flight are briefly described. Testing is divided into two major sections: the wet countdown demonstration test/flight readiness firing, which includes a 20 second test firing of the orbiter's three main engines, and a mission verification test, which is centered on flight and landing operations. The functions of the countdown sequence are listed and end of mission and mission abort exercises are described.