It may sound silly, but imagine what would happen if a rocket sent up to the moon missed its target. The moon may be pretty big. But so in space. Missing something even as big as that could easily happen, without careful control of the spacecraft. That’s why each moon shot takes months of planning and complicated calculations.
The rocket must be programmed so that soon after take-off it reaches almost 42,000 kilometres per hour. This is the speed necessary for it to break free of the earth’s gravity. After that, its speed has to be carefully controlled so that when it reaches the moon it will be travelling at about 1250 kilometres per hour.
Of course, while a rocket is flying to the moon, the moon is on the move as well. It is whizzing round the earth at an average speed of 3836 kilometres per hour. Just to complicate things further, it does not stick to a regular path. The distance between the earth and the moon can vary by as much as 52,800 kilometres! The flight controllers have to work out where the moon is going to be all through the flight, to be certain that the rocket reaches the right place at the right time. Then there is the moon’s gravity to be taken into consideration. The closer a rocket gets to the moon, the more it is affected by this gravitational pull. So for the last 3000 kilometres the scientists have to watch the rocket’s speed very closely as it becomes more and more affected by the moon’s gravity.
You can see that controlling the speed and navigation of a spacecraft is anything but easy. The speed has only got to be a couple of kilometres an hour either side of the right speed to miss the moon completely. And one degree off course could throw the rocket’s timing out by as much as seven hours.
Picture Credit : Google
