Here’s how Elon Musk’s giant moon cannon would actually work

“I really want to see a mass driver on the moon that is shooting AI satellites into deep space,” Elon Musk said last week when he announced his plan to go to the moon. “It’s going to be incredibly exciting to see it happen.” He’s right. I want to see it too, although probably we will both be dead before his vision is realized.

The lunar mass driver—essentially a cannon that uses magnetic power to accelerate an object—is a key component to launch the million satellites Musk wants to put in orbit around the Earth.