U.S. President Donald Trump picked a design for his Golden Dome missile defense system and named a leader of the ambitious $175 billion defense program. Here are details on Golden Dome, where the idea comes from and how it will work.

President Donald Trump picked a design for his Golden Dome missile defense system and named a leader of the ambitious $175 billion defense program. The program, first ordered by Trump in January, aims to create a network of satellites, perhaps numbering in the hundreds, to detect, track and potentially intercept incoming missiles.

“One key reason why the midcourse phase is difficult is because you’re in space, and different objects of different mass travel exactly the same,” physicist James Wells, coauthor of the APS report, told ScienceNews. “That’s been the bugaboo of midcourse intercept from the very beginning.”