Liftoff!

The countdown does not start with the famous “10 … 9 … 8 … 7” etc. The official countdown for an Apollo mission launch actually begins the day before.

Countdown starts 28 hours before the scheduled launch time with the announcement: “T-minus 28 hours and counting.” From this moment on, every man involved in operations at Cape Kennedy is on highest alert.

The massive service structure withdraws to a parking area a mile and a quarter away from the launch pad by T-11 hours. The Saturn rocket capped with the Apollo spacecraft sits on the pad, monitored by sixty TV cameras sending data back to 15 display screens at the Launch Control Center, overseen by technicians sitting at 150 consoles.

By T-minus 2 hours 10 minutes the crew has been strapped into the command module, three abreast. The hatch is closed and sealed thirty minutes later. The LES – Launch Escape System – is armed.

T-minus 3 minutes 10 seconds:

   A firing command initiates the automatic launch sequencer.

T-minus 50 seconds:

   The Saturn V rocket is now under its own internal power.

T-minus 10 seconds:

   Thousands of gallons of water splash into the flame trench below the rocket.

T-minus 9 seconds:

   The Saturn’s five F-1 engines ignite.

T-minus 5 seconds:

   The IU (Instrument Unit, the rocket’s guidance system) assumes control.

T-minus zero:

   The hold-down arms release and the engine thrust reaches maximum.

LIFTOFF!

T-plus 12 seconds:

   The rocket clears the tower.

   At this moment, Houston takes over from the Cape.

T-plus 2 minutes 30 seconds:

   The rocket is approximately 40 miles above the surface, traveling at over 6,000 miles per hours – almost Mach 9, nine times the speed of sound. Now the second stage ignites.

T-plus 9 minutes:

   The rocket is approximately 110 miles up, racing up at 16,000 miles per hour – about Mach 22. Now the third stage ignites.

T-plus 11 minutes:

   The spacecraft reaches Earth orbit.

T-plus 3 hours (approximately):

   After extensive checkout, the spacecraft receives a “GO!” for TLI – Trans-lunar injection, and from now it is three day trip to the Moon ….