Hitting a moving target is always a challenge. Hitting one — or rather NOT hitting one — that is millions of kilometers away is a bigger challenge. This time, NASA was up to the task. Its latest robot probe to Mars survived orbital insertion today, and can begin its detailed scrutiny of the martian surface.
The cliffhanger in these maneuvers always seems to happen on the blindside of the planet or moon in question, where radio signals from earth cannot go. So space probe teams always anxiously await the A-OK signals from their babies with bated breath. If you have ever seen the movie Apollo 13, you can get a sense of what I mean.
Details about the Mars Reconnaissance Orbiter are here, among other places.