While the US was celebrating the Fourth of July, New Horizons was getting itself drunk. Well, there was a glitch. With just ten days to go until the encounter with Pluto, New Horizons shut down its main computer and the backup started up, putting the probe in safe mode.
Safe mode isn’t unusual for space probes, but the timing isn’t very good. Well, it’s not so bad, because not many pictures were expected to be taken over the next couple days. However, New Horizons is 4.5 hours away, and any commands will require 9 hours (4.5 hours confirmation). If they can diagnose it quickly, then it should be working properly in the next couple days. If not, it could take a few days to correct. I really hope it’ll be corrected soon. I want my Pluto pictures!
The Planetary Society has a very good write-up on this.