Early Sunday morning, SpaceX mission CRS-4 lifted off from Cape Canaveral towards the International Space Station, carrying with it the first 3D printer that will operate in zero gravity. When the astronauts aboard the ISS use the 3D printer, they will become the first humans to ever manufacture goods away from planet Earth. It's not quite the Moon- or Mars-based factory that we've always dreamed of, but it's a very important first step towards manufacturing goods outside of Earth's gravity, and thus the eventual colonization and industrialization of the Solar System.