Page "Apollo 16" Paragraph 23

The official mission countdown began on Monday, 10 April 1972 at 8: 30 AM, six days before the launch.

At this point during the pre-mission preparations, the Saturn V rocket's three stages were powered up and drinking water was pumped into the spacecraft.

As the countdown began, the crew of Apollo 16 were participating in final training exercises in anticipation of a launch on 16 April.

The astronauts underwent their final preflight physical examination on 11 April.

On 15 April, liquid hydrogen and liquid oxygen propellants were pumped into the spacecraft, while the astronauts rested in anticipation of their launch the next day.