Sorry folks, things are about to get heavy, by which we mean that SpaceX has begun test-firing the boosters for the Falcon Heavy. The company posted a clip of the event from last week, showing a side booster being put through its paces. Elon Musk subsequently tweeted that, when the Falcon Heavy launches, it'll be this powerful, but "times three." The CEO added that "one way or another, launch is guaranteed to be exciting."