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Death to dinosaurs
Of course, we know what happened to dinosaurs. Earth's climate may have changed when a massive asteroid smashed into what is now Mexico's Yucatan Peninsula and triggered cooling temperatures that wiped out the creatures. The asteroid left a 110-mile-wode crater near Chicxulub, Mexico.
Missions to come
One of the biggest upcoming asteroid threats found is from 500-yard wide "1999 RQ36." It has a 1 in 2,400 chance of impacting Earth in the late 22nd century. NASA plans to send the OSIRIS-REx to land on the asteroid and take samples for further study. It is expected to launch in 2016, arrive in 2018, and work until 2021, then return to Earth with its findings and samples. Above is the sample collector.
NASA is already studying asteroids. After traveling 1.7 billion miles over four years, NASA's Dawn spacecraft began in 2011 sending images of the asteroid Vesta back to Earth. This is the first image sent when the probe was about 3,200 miles from the asteroid.