Testing was delayed for years as engineers figured out what it would take to keep three Falcon-9 boosters—and their 27 Merlin engines—together and headed on the right trajectory when they at last ignited. We finally got a sneak peak of what that would look like when SpaceX put the Falcon Heavy through a dress rehearsal on Wednesday, firing up the engines for 12 seconds on the pad.
Billowing steam created a brief, massive cloud around the launch site. Just check out SpaceX’s footage of the test fire:
Of course, sitting on the launchpad for a quick test fire is a little different from actually launching (and then simultaneously landing three boosters at three different sites).
There’s every chance that the launch could still go horribly wrong. But a successful static fire is at least a step in the right direction.