Priska Neely

This week, a 3-D printer fabricated a part for itself. Normally, that wouldn't make headlines — except that it happened in space.

"It's a history-making moment for us because it's the first time ever that we're talking about transitioning from launching every part we might need in space from Earth, to actually being able to email a file, a design to space and make that part on demand," says Niki Werkheiser, the project manager for the International Space Station 3-D Printer at NASA's Marshall Space Flight Center in Huntsville, Ala.