> If it hovered for 5 seconds at .5 meters, for example, could it burn off enough extra fuel?

The Falcon 9 cannot hover. The thrust of the single landing engine, even when throttled down to minimum, will provide significant lift to the empty rocket. That's part of what makes this maneuver so difficult and so awesome: it's called the hoverslam, where you achieve 0m altitude and 0m/s velocity at time = 0.

For reference, though, the Grasshopper/F9R-dev1, could hover due to it only having 3 engines, not 9, and because they could ballast it with additional fuel.

> it's called the hoverslam, where you achieve 0m altitude and 0m/s velocity at time = 0

Also known as making a "suicide burn", at least in the KSP world.

Their eventual goal is for every rocket to land and not have problems. Providing enough fuel for five seconds of hovering is a waste of valuable fuel (see how they're already so low that they run out in the process).

Also, falling over almost certainly also leads to a writeoff, as otherwise they'd just fly the rocket into a big pit of fire retardant foam blocks.

I'd imagine that the lateral stresses involved in a crash landing are more than enough to write off the rest of the rocket, and so the explosion would just make the barge slightly harder to clean up.

Of course, their plan is to not have problems. That's everyone's plan. It's planning for when things don't go right that makes the difference.

They are planning for when things go wrong, which is why the landing ship is unmanned and in the middle of a big exclusion zone in the ocean.

I'm talking about the economics of failures. Insurance prices will go down, the cost to orbit will be cheaper. Could probably land at the Cape, decreasing turn around time. We'll have flights everyday!

The explosion isn't going to cause significant damage to the landing ship or the landing pad. There isn't much fuel left onboard at that point anyway, so it's fairly superficial. The rocket is scrap if it falls over regardless of whether or not it explodes, and the explosion won't hurt much, so there's not much reason to put effort into reducing the risk of an explosion in a crash. The plan is to eventually land at the Cape once the technique is proven, but there's no need to make a rocket that can tip over without blowing up to achieve that.

Ok, just thought the rocket could be salvaged if it didn't get blown to pieces. That's the goal. Reusable rockets are going to lower the cost.

I think that once it falls over, it's scrap. There's so little margin that once you even suspect things are bent, you pretty much have to rebuild it anyway.

I imagine making the rocket sturdy enough to withstand falling over would be prohibitive in terms of both costs and reduced capacity, so it makes sense to them to ignore this problem completely and work on perfecting the landing so that the rocket does not fall over.

> Finding a way to prevent an explosion if it falls over after landing seems worthwhile.

They probably are spending more effort into not letting it fall over.