After a 10-year journey, NASA's New Horizons spacecraft sped past Pluto for just a few short hours in July 2015. It was going far too fast to enter an orbit around the dwarf planet—let alone land on it—but along the way it grabbed some pretty amazing photos of this mysterious world.
The Pluto flyby was arguably one of 2015's top scientific achievements, maybe even one of the most memorable moments in the last decade. We now know what our ex-ninth planet looks like, and it's spectacular. Pluto turned out to have some surprising features like glaciers, nitrogen lakes, ice volcanoes, and the list is growing. The New Horizons mission to Pluto has surpassed everyone's expectations, and the good news is, the team has no plans of stopping yet. This summer, they're hoping to win an extended mission to explore another strange new world.
Plutonium-238 is the fuel that is driving the Mars rover Curiosity across the Martian landscape. It flew the New Horizons spacecraft to Pluto and beyond, and is still powering the Voyager probe into the depths of space 38 years after it was launched. It's a fuel that is in high demand and very short supply.