How Do You Know Where the Moon Is Going?

Astronauts had to work out where the moon was in three days time. They could do this by monitoring their position and using stars as beacons. But getting there is only half the job, they need to get back too. The return leg of a space mission is like an uphill struggle leaving earth. You start off very fast but soon run out of speed so you have to slow down. And that means falling faster and faster towards the moon's orbit. As you fall nearer it becomes more gravity-defying which causes your spacecraft to drift away from its intended course. So if you don't burn your engine quick enough then you will zoom past the moon and into somewhere elsetho