It's not really one discovery, more just the culmination of it all. The moon landings happened before I was born, but that was impressive and emotional for everyone on our planet. A Mars landing someday will provide a similar situation. Manned exploration is just super emotional for me and makes me happy and excited for the future. A future I won't be around to see, but I'm glad that even though we aren't doing much, at least we're doing something. Our fate is to eventually live out there somewhere.

I got super emotional when Challenger failed, I got even more emotional when I read the true story that they weren't killed by the explosion but more likely the impact with the water minutes later. I got emotional when Columbia broke upon re-entry. On the other end of the spectrum I was happy watching the shuttle launches, I was happy watching Soyuz launches, I am extremely happy with how the private companies launches are going. I shit-you-not got quite emotional the night of the Curiosity rover landed successfuly, as I had been waiting for that for years. Kepler was another probe I anxiously awaited, and it's proved some amazing things and helped solidify the Drake equation a bit better. Sure these are just individual experiments and probes and missions, but the whole idea of what they are trying to accomplish moves me to great levels of emotion. It's inspiring and exciting. They are the modern day pioneers of the only frontier we have left.

Sure, I'm not a part of any of these things, nor did I help build them, design them, or do any of the ground breaking physics that lead to these devices and capabilities to help us explore space... but I'm a human. And space exploration is about being a human, and figuring out where we came from, and where we are going next. There's nothing more spiritual than that.

But if I had to choose one discovery, it would be when they figured out where the elements of the periodic table came from, and that all that stuff was manufactured in stars before our solar system even formed. To know that stars are responsible for the chemistry within our bodies. To know that when I'm looking up with the stars it's not so distant feeling. We aren't "a virus" as many critics say, we're just another part of this universe, and we're made up of the same stuff. And so far, we're the only species that we know of capable of understanding it, and exploring it, so I feel like we owe it to 13+ billion years of the universe's existence to explore it a bit.