The Falcon Heavy is essentially three of the SpaceX's Falcon 9 rockets bolted together. With a total of 27 Merlin engines, it's capable of generating more than 2.3 million kilograms of thrust at lift-off. That is also slightly more than double that of the second most powerful rocket -- the Delta Four Heavy -- operated by rival United Launch Alliance. SpaceX's rocket is able to lift 64 tons into orbit, double the lift capacity of the Delta Four Heavy, at one-third the cost. The Falcon Heavy was designed from the outset to carry humans into space, including to the Moon and Mars.