While human spaceflight is certainly compelling – and it has always been a big part of my reporting career -- there is something about unmanned robotic spacecraft that has always tugged at my heart. These machines are our emissaries out into the cosmos, flung to faraway places that humans can’t yet visit. I grew up hearing about spacecraft like Mariner, Viking and Voyager boldly going on some of the first-ever deep space missions and making monumental discoveries that changed our view of the Solar System. They showed us worlds we previously could only dream about and artists could only imagine.

Part of what drives us to explore and discover is the intangible: expanding our horizons, feeding our curiosity, finding all those unexpected things, and trying to answer those profound questions discussed in previous chapters, like how did the universe begin? How did life begin? Are we alone?