The shuttle launch pad, officially known as Launch Complex (LC) 39 Pads A and B are the last steps in the process of preparing a shuttle mission into space. The pads have supported NASA in many of its vehicles: Apollo/Saturn V, Skylab, Apollo-Soyuz and the Space Shuttle. The tower stands 347 from ground level to the tip of the lighting mast, which itself is 80 feet tall and grounds the Pad from potential weather hazards. An important floor on the structure is the 195th, which is the point where the astronauts enter the orbiter. At the far end of the level is the Emergency Egress System which is a rapid escape system for any crew on that floor during an emergency. On the same level, the Orbiter Access Arm allows astronauts and support crew to enter the shuttle while it is on the pad. Other arms on the structure feed fuel into the External Tank and helps vent excess gas.