Greatest Hits of Space Exploration in 2014

I'll admit it, I am a sucker for year-end lists. If I'm reading one, it is a fun provocation for disagreement. If I'm writing one (like now), it is a welcome opportunity to separate the timeless from the ephemeral. Either way, such lists inspire an invigorating reconsideration of the events of the past 12 months--and for those who care about the human exploration of the universe, 2014 was a momentous year in many way. Not all of the year's developments were positive, of course, and not al