Killer asteroids abound. Nasa is ready to do something about it

A researcher holds pieces of a meteorite that they identified as coming from the asteroid Vesta at the Field Museum in Chicago. After years of study and discussion, Nasa has launched its first effort to spare Earth the kind of calamity that extinguished the dinosaurs, crashing a space probe into an asteroid to alter its speed and course. — Chicago Tribune/TNS

The Russia incident was a warning.

On a winter morning in 2013, a meteor the size of a four-story building screamed across the country, exploding near the city of Chelyabinsk and injuring more than 1,600 people amid widespread property damage.