Watch SpaceX fire up the Falcon 9 rocket that landed in May

SpaceX has landed five Falcon 9 rockets since the company started trying in 2015, but yesterday it put one of them through the first major test to see if it will ever fly again. The company posted a video to YouTube last night that shows the tied-down rocket firing at full thrust for just under three minutes — essentially the same amount of time that they would fire during a normal trip to space.
This particular 14-story-tall rocket was used to send a Japanese communications satellite to s