NASA just smashed a spaceship into an asteroid on purpose. Here are 13 facts about the mission and why it may just help save humanity one day.

NASA/Johns Hopkins APL

• NASA crashed a spacecraft into an asteroid, in a first-of-its-kind experiment in planetary defense.
• The space agency wants to see whether it's a viable method for deflecting rocks that could threaten Earth.
• Here is how this experiment works and why it is important, in 13 facts, photos, and graphs.

NASA made history on Monday when it purposefully crashed a spacecraft into an asteroid about...