astroengine writes What better way to understand how to deflect an incoming asteroid than to smash into one to see what happens? This may sound like the storyline to a certain science fiction movie involving a team of oil drillers, but this is science fact, and Europe has started planning a mission to map a small target asteroid that NASA will attempt to shoot with a speeding spacecraft, no nukes required. As the first half of the joint Asteroid Impact & Deflection Assessment mission, the European Space Agency this month has started planning for the launch of its Asteroid Impact Mission (AIM) in October 2020. AIM's target will be the binary asteroid system of Didymos, which is composed of a main 800 meter-wide hunk of space rock circled by a smaller 170 meter-wide asteroid informally known as "Didymoon." It's the smaller asteroid that the joint NASA/ESA mission is interested in bullying.