The rocket has its center of mass very low during landing, as it's mostly an empty shell by this point, with heavy engines at the bottom. So take a meter tape, pull it out a bit, lock and try to balance that. Much easier, right?
The magic is in a) ensuring the whole construct survives reentry, and b) timing the landing burn - even a single Merlin engine is too powerful for the almost empty rocket to hover, so they need to zero out their velocity at precisely the moment they're hitting the ground. There's no second attempt.
> even a single Merlin engine is too powerful for the almost empty rocket to hover
Indeed. For their last launch, they decided to try landing the booster with three engines rather than one, which brings the whole 'hoverslam' concept to the next level.
This was considered so risky that they didn't try landing it on the barge, for fear of damaging it. Instead, they soft landed on the ocean.
But much to everyone's surprise, it actually worked! There's a picture of the Falcon 9 booster floating awkwardly. Musk said they'll try to tow it to shore.
And all that is really the core of why I love SpaceX: continuous improvement. It's a grand thing!
I decided I had no way to guess on the mass distribution of fuel, engine, and airframe, plus wind shear, so I went with the hard scenario. If anybody knows the numbers for this, I'd love to hear it!
The magic is in a) ensuring the whole construct survives reentry, and b) timing the landing burn - even a single Merlin engine is too powerful for the almost empty rocket to hover, so they need to zero out their velocity at precisely the moment they're hitting the ground. There's no second attempt.