For future reference, the return part is made up of 3 burns. The first two use three engines, and the landing burn uses just the one. Coming back, it's obviou

For future reference, the return part is made up of 3 burns. The first two use three engines, and the landing burn uses just the one. Coming back, it's obviously much lighter without all the propellant and 2nd stage/payload weight, so it needs much less thrust to reverse course. See http://flightclub.io http://flightclub.io for more info.