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Comment by mholt | Hacker News Reader

To put this in perspective, they just landed a supersonic toothpick upright on a turbulent matchbox.

It was a unnervingly close to the edge of said matchbox. Can't they build a bigger drone ship? Seems a lot cheaper than losing one over the side.

So far they haven't lost any of them because of the size of the ship. People keep saying they should build a bigger or more stable ship, but every loss so far has been because of things like failed landing legs, sticky valves, or insufficient hydraulic fluid.

I would think better than bigger is more stable; instead of a conventional barge, they could use a semi-submersible or some other optimized hull form to ensure a more favorable motion response in a given sea area. I think I remember reading that they use a run-of-the-mill cargo barge, which is probably ideal for logistics compared to a highly specialized vessel.

I'd love to hear from naval archs or hydrodynamicists who are working on this (surely there are some).

If the circumstances would cause them to lose one over the side, it's probably already lost.

Couldn't they make the landing pad a bit more forgiving? Like have two big ring-halves pop-up around it when it lands and "catch" it if it tips. I know they'd want to eventually master landing without it, but not having the whole thing explode seems like a good way to quickly run new flights.

No point in spending big on small optimizations like that while they are still working on the part of the process that contains 99% of the difficulty. So far the recovered rocket parts probably have little more value to SpaceX than a very interesting log file. Even if they already send this one up again, it will be more to show off (which is perfectly fine) than for direct monetary reasons.

Once they have an economically meaningful recovery rate, advanced landing pad features might still become a tool to get some margin of error or to reduce the rocket mass overhead necessary for landing. But right now, just tipping over instead of dropping like a meteor (or stopping in mid-air like a cartoon animal, then dropping) is still the goal, not the most pressing danger.

I did a bit of research on that after a comment by Josh here on HN, basically when the first stage isn't pressurized by all of the propellant it is more like an empty beer can. (ok a really really tall beer can :-). Once it is on the barge it has the gas thrusters on top (you can see them in the video) which are well positioned to provide maximum torque to the rest of the structure, but they have limited amounts of reaction mass.

The next step would be some way to secure the booster, post landing, in a structurally supportive way, on the barge. I can't wait to see how they pull that off.

They have clamps that they were planning on welding to the deck to keep the rocket attached.

That would be interesting. I was thinking perhaps a set of explosive bolts on the landing legs which punched into the deck once it was stable.

I was also quite pleased that they had solid video of it coming into land with a drone that was hovering off barge. That was a brilliant move on SpaceX's part.

In the new field of vtoL rocketry, you want to have as much of the landing gear as possible on the pad and as little as possible on the rocket. An expensive array of mass produced "autograpples" embedded in the platform would be preferable over any solution that adds mass to the rocket.

That was actually NASA's plane that was doing the filming!

You realize the rocket is 15 stories tall and made of aluminum foil under high pressure, right? Any means of "catching" it is indistinguishable from a collision. That's besides the absurd scale and cost of building such a thing.

It's far too fragile for that sort of thing. The moment you tried to catch it, you'd break it. The only solution is to keep it upright to begin with.

Indeed.

When I launched the replay of the live stream at whatever point it was, when I heard the wild cheering I knew they had finally landed a first-stage at sea before I even saw the footage of that supersonic toothpick landing.

Like throwing a pencil over the Empire State Building and landing it perfectly.

Except your example would be much harder =P

Well, equip that pencil with computers and propulsion and steering systems, and it might be possible ;)

Paper fins on the eraser end and waiting for a snowy day would be easier.

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