[snirp]

In all fairness, it was not completely shut down. The main computer and some heating was left active. I do not think that time keeping was biggest worry.

That being said, a hundred other things could have gone wrong and mission control would have had no idea that something happened. Meteorite impacts, misalignment of the solar panels, software bugs, radiation damage and a faulty wake-up sequence are just some things that spring to mind.

Bad thing is that most of these could result in the spacecraft not even being able to send out a ping. Or any information that would tell engineers what went wrong and how to fix it for future missions.

Imagine just listening to silence and not being able to find out if any of it was your mistake.