[codecamper]

This is the second time something like this happened. Why not put 4 tall posts up - equidistant from each other - a square.

Then a wire net between the posts.

When it tips over, it can just fall into the wire net.... they could even have motors to unwind a little while it leans over on them to allow "soft catching" the rocket. Foam over the wires would help here.

Actually... why not skip the barge & the dramatic landing and just catch it with a big underwater net? I suppose getting the rocket wet with salt water is not good? (the inside is covered with liquid spill indicators which void the warranty?)

[NamTaf]

2 reasons:

1) As you say, salt water is bad. Do never go in salt water if you want metallic, electronic things to keep working.

2) The rocket can't withstand much, if any, load in longitudinal bending mode. It'll buckle like a toilet paper cardboard tube. This almost certainly includes under its own weight, if you were to 'catch' it at the top of the rocket and hold it on an angle. To design against that, you'd be adding way too much weight to the structure to make it worthwhile.

[LewisJEllis]

Rockets are more fragile than one might think, but even assuming that would work, it's significantly more useful to be able to land just about anywhere that's flat.

Also, we don't have giant posts and nets waiting for us on Mars.

[bobbles]

I guess if you optimised for a net 'landing' you'd also be losing the ability to realistically land anywhere you want, since you'd have to have a net there. learning this way would potentially open up any flat surface

[usrusr]

My initially reaction were similar ideas, but thinking about it some more i am not sure if the empty tank could tolerate the stresses from getting caught in a net. And with a landing strut failure like today, you would probably lose the engines even with the tank not completely tipping over.

But SpaceX seem to be exceptionally good at control systems, fast and precise automated planning. Maybe they will just skip the level of passive rocket catcher structures and intend to move directly to a three-axis actuated landing table? A system like that that could take responsibility for a tiny little amount of deceleration (think extra suspension) and a fair bit of balancing completely outside of the mass budget of the rocket.

[codecamper]

3 axis table? Do you mean that the platform would be able to shift either way to keep it from wobbling over? That seems hard given that a rocket is tall & skinny.

How about a massive electromagnet underneath?

[usrusr]

Tall and skinny is exactly what you would want for dynamic balancing. Unfortunately, an empty booster would have a very low center of gravity compared to the external shape.

[ansible]

Anything other than a perfect vertical landing is likely to result in damage to the structure and components. Thus negating most of the value in landing the 1st stage.

Sea water is also highly corrosive to many materials.