By BBC News Online's Helen Briggs in Kourou, French Guiana

Moments before the countdown began, we all rushed out on to the roof terrace of the Jupiter Control Room.

The rocket was visible in the distance on the launch pad, glowing white against the darkness.

The mighty Ariane 5 rumbled straight up into the night sky

The seconds ticked away: "Dix, neuf, huit..." and we all held our breath.

For a moment the rocket seemed to linger on the pad and then the sky turned orange and the mighty Ariane 5 rumbled straight up into the night sky.

At first, it seemed to fizzle like a giant sparkler, then the sound turned into a deafening boom and it soared in an arc towards the ocean.

Magnificent show

The rocket seemed to pass almost overhead, leaving the smell of burning in the air and a tail of thick, grey smoke before it disappeared out of sight.

"Fingers crossed now for 26 minutes after the launch," I heard someone say, and we all hurried back into the control room, where the mission managers were still working hard.

My stomach twists like a rubber band

Eventually, news came through that the spacecraft had successfully separated from the rocket. Only then did they clap, stand up and shake hands.

Even those who have watched many launches say they are still moved by the sight of a rocket soaring into the sky.

"My stomach twists like a rubber band," is how one seasoned observer describes it.