I'm John Batchel with my colleague Bob Zimmerman.

His book is Genesis, The Story of Apollo 8, the First Man Flight to Another World.

It is December of 1968.

The mechanics of launch give them a six-day window.

And what does that mean, Bob, six-day window and what does that mean bob six-day window

it means they they can launch within that six-day period and do their mission of the

moon and the earth is in the same is in the right position to do so they were fortunate they

were no delays they launched at the very first opening of the window and launched on December 21st on their way into Earth orbit.

And then they spent about one full orbit in Earth orbit testing their systems out to make sure everything was working

because they didn't want to leave Earth orbit unless they knew everything was okay.

And then once they had done that and they reached the point in the Earth orbit,

where it was time to fire the upper stage Saturn engines that would power them to the moon,

they got the go-ahead from Capcom.

That's the guy who talks to them from the ground.

And in this case, it happened to be, it's always an astronaut.

In this case, it happened to be Mike Collins, who was on the Apollo 11 mission that

was to follow.

And Mike Collins said to them, your goal for TLI.

TLI is trans lunar injection.

That's the technical term they gave to that firing of that engine.

So the astronauts fired the engine.

And for the first time,

...