And coyote is right, over 40% of any past probes that have been sent there have failed. We're getting better
at it but not as good as we would need to be. Most of the past failures were due to reentry, or communication problems. The seven minutes waiting to see if we made it or not cuts down on our reaction time. A lot can go wrong in seven minutes and that's only one way.
That's what happened to the Japanese years ago when they tried to send a satellite to Mars. The 14 minute time lapse was to long for them to adjust its course. Results? A spectacular fireball reentry.