Yeah they were attempting to land all 3, but the center booster (which would have landed on a barge at sea) had issues relighting it's engines during the landin

Yeah they were attempting to land all 3, but the center booster (which would have landed on a barge at sea) had issues relighting it's engines during the landing burn. They setup the landings so that they are on a trajectory to hit the ocean, and only if everything goes right do they then adjust course to the landing pads. This gives them an additional failsafe which the center booster took advantage of here. Instead of crashing into an expensive barge in the ocean, it just splashed down into the ocean purposely missing the barge. [1] is a diagram that kind of shows what this looks like for land based landings, but it's very similar for barge landings too. And don't worry, they are going to be flying Falcon Heavy again soon-ish, so there's another chance to land all 3! [1] http://i.imgur.com/D9BdO86.png http://i.imgur.com/D9BdO86.png