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Why must you land the boosters on a flat surface? Why not aim for a cone a deep net that can accommodate rough seas, winds, etc?

A picture is below - obviously I am not an artist nor an engineer. Capturing a booster in a depression

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  • $\begingroup$ You're referring to SpaceX's new vertical landing concept? $\endgroup$ – HDE 226868 Jan 17 '15 at 17:42
  • $\begingroup$ That's actually not a half bad idea -- although implementation would be a challenge. One might simply ask why not just use an enormous net... $\endgroup$ – Erik Jan 17 '15 at 18:31
  • $\begingroup$ It may not be technically practical, but that's a really cool idea! $\endgroup$ – raptortech97 Jan 18 '15 at 3:45
  • $\begingroup$ If you have sufficient control systems and actuators to get anywhere near a particular site, the fine tuning to land just so seems free. $\endgroup$ – Nick T Jan 19 '15 at 0:16
  • $\begingroup$ this is pure speculation hence comment not answer, but from what we know of Elon Musk's personality, I'd say a big driver is that sitting a rocket on its tail under rocket power just looks awesome. $\endgroup$ – Joseph Rogers Feb 9 '18 at 9:46
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Your proposal wouldn't help. When the rocket hits the edge of the cone, the rocket will still be damaged. The cone also traps the exhaust gases so you'd have to add insulation to the rocket.
Rockets are flimsy: they are built from the lightest materials they can get away with. This means you have to be careful when you transport the rocket. Some rockets need to have their fuel tanks pressurized, otherwise they will collapse under their own weight.
Making the rocket heavier (so it can withstand a rough landing) means it will carry less payload. For now, this is a big issue. If rockets become fully reusable, it's likely they will become heavier and sturdier too, but until then SpaceX has to design a landing strategy that works with the rocket they have.

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I'll second the earlier answers by @Hobbes, and @HDE226868. Aiming for a hole in the ground would be a trickier task, to say naught of the potential damage to the fuselage.

The idea of a net could be probably be used on a flat surface though. Here are a couple of thoughts to begin with

Obviously the above two systems are passive devices. An active device could probably be used to flip a net over the fuselage to catch it before it topples; a glorified snare gun say.

p.s. Obviously I may be talking through me hats here. Feel free to down-vote/delete!

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    $\begingroup$ Thoughts: Kill engines 20 feet off above platform assuming you must get there above a solid platform or a very generous net (as wide as is needed to minimize the chance of rocket colliding with wall edge) 2. Net--something akin to Chinese Finger traps with self-centering lateral supports to allow the most distal end to center into the net as it drops into the ocean/net cone--the net narrowing to rocket diameter as it moves distal (like holding fingers during a both bones forearm reduction). If the booster is a lunar lander, why not land on solid ground. If impossible, drop it into a net? $\endgroup$ – phil Jan 18 '15 at 22:45
  • $\begingroup$ @phil Yep. Along those lines - easier said than done though, I fear. Those self-centering lateral supports could probably be implemented with a take-off from the way ILS works. In fact they may be using a souped-up ILS to track the spacecraft to the barge... $\endgroup$ – Everyone Jan 20 '15 at 18:49
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Landing a rocket on a flat surface can be tricky. An airplane pilot could tell you all the different factors necessary for landing an aircraft: angle of attack, horizontal speed, vertical speed, braking - and these are just the things that can be controlled. When it comes to landing a plane, there's one thing in your favor: it's tough for the plane to fall over. Yes, it's happened in the past, with disastrous consequences, but in general, a planet is more likely to stay at the angle it's landing at.

Rockets can be different.

Looking from above, their center of gravity is in the middle of a very narrow cylinder. Tilt the rocket too much one way and its trajectory could change. When you're aiming for the ground, a slip like this could mean that the rocket falls over sideways and explodes. That's not the optimal arrangement.

That's also the problem with your setup. You show a conical depression in the barge, with the rocket leaning against it. That kind of landing would be the worst possible, because the rocket is going to come down vertically - as planned - and then fall sideways and hit the wall of the chamber, most likely resulting in severe harm, if not total destruction.

You could make the chamber in the shape of an upside-down conical frustum, but at this point we're back to having it land on what is essentially a flat surface.

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