Mobile Launcher

The Saturn V launch vehicle is assembled, transported on, and launched from the Mobile Launcher. This structure consists of a base platform 48.8 x 41.1 metres and 7.6 metres high with a 13.7 metre square hole over which the vehicle is mounted. (The platforms were later converted for use by the Space Shuttle.) Sprouting from one end of this platform is the LUT (Launch Umbilical Tower). This 116 metre tower bears nine swing arms which provide the ground crew with access points to the vehicle, and a wide range of services including fuel, LOX, hydraulics, electrical power and various gases for purging and pressurization. These arms are articulated so they can swing away from the vehicle to give it clearance as it rises, and to protect them from the rocket's white hot exhaust gases. The crew enter the spacecraft via the top, or ninth, arm, which carries an environmentally controlled room at its end. Known as the "white room", it covers the CM hatch until the crew is aboard. 43 minutes before launch, it is swung away from the spacecraft by 12°. Five minutes before launch, it completes its retraction to 180°, on the opposite side of the tower from the Saturn V.

Once the ninth arm and white room are clear, at about T minus 43 minutes, the crew lock their shoulder harnesses and John Young arms the Launch Escape System (LES). In event of an emergency the crew will then have the option to use the LES to launch the CM alone, away from the pad. See description at 000:03:27 for the details of the LES.

The Flight Plan indicates that in the CM, the five launch vehicle indicator lights are illuminated at T - 4 minutes, 10 seconds. Throughout powered flight, these lights, arranged to resemble the pattern of the engine clusters on the S-IC and S-II stages, will provide the commander with cues about the progress of the boost and the status of each engine in each stage. Readers can familiarize themselves with this subpanel through the movie Apollo 13. Two events in the film that focus on this panel are when Tom Hanks (as Jim Lovell, Apollo 13's commander) manually jettisons the Launch Escape Tower, and when the inboard engine of the S-II stage prematurely shuts down. Then we see one of the few flaws in this movie, otherwise known for its incredibly high standards of accuracy. The central light is shown to blink on and off. In reality, it simply changes from on to off or vice versa.

Dave Scott, from 1998 correspondence - "In Apollo 13, the movie, the light was purposely made to blink to get the viewers attention - the movie-makers knew the actual operation, but chose to take this license for dramatic effect (actually a pretty good license, as otherwise, the viewer would have missed the point!)." (ap15fj)