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Comment by HlessClaudesman | Hacker News Reader

OceanGate was stretching the lifetime of it's reusable Titan submersible.

You really think this is comparable to bring it up ?

Worst case a few sats get lost or the booster doesn't land correctly. As long as they test this on their own sats first (which are rather cheap) I do not see the issue.

They will want to test to breaking point after all.

From the article: certifying Falcon 9 boosters for up to 20 flights for Starlink missions

So yeah, seems that they want to reduce their starlink cost

Rocket blows up on the pad? Needs self-destruction after launch and the self-destruct doesn't work?

Still, there aren't any people hanging out at the pad during a launch.

There is a pretty good reason why they launch rockets over the ocean or large expanses of empty land. If an RSO terminates a flight with a perfectly functional system, the debris will still spread over the surface for some distance, depending on the altitude that the flight was terminated at, of course. Launch trajectories are designed in such a way that the portion where the altitude would allow substantial debris to return is usually placed over uninhabited regions or the ocean.

The recent SpaceX explosion had debris that fell on towns and inhabited areas.

For the most part it was a dust and maybe a few tiny rocks. This was mostly because because the wind carried it in that direction.

No people were hurt and no windows were broken.

A rocket is a lot easier to design for (in a weird way) -- after all, it only has to deal with zero to one atmosphere, instead of 150 atmospheres.

Are you forgetting that little something at the back of rocket that is so hot it can melt itself?

Even managing propellant tanks is complicated dilema. Take a big jug of water that is half full and slosh it around. Its one of thousands small things that needs solving. And solutions need to be implemented with as few grams as possible.

A rocket is easier because it doesn't have people in it. But if there are not people, its much harder.

You're right, rocket engineering is not as simple as some people would have it sound.

I think the SpaceX organization has proven to be prudent risk takers. They have had many spectacular failures, but they have been good at communicating the risks ahead of time.

Make that 450 actually :)

James Cameron spent 10M to built his submarine. It is impossible at present time to build a orbital manned rocket for that amount. Therefore the submarine is easier to design and build.

And that had people in it. A rocket and capsule you can put people on is gone cost you billions.

Hmm. The pressure inside a Merlin engine is about 1410 psi (about 88 atmospheres) and the temperatures inside the engine reach 2200 C. The turbopumps in the engine spin at about 3600 rpm and produce about 10,000 horsepower, which is just used to pump fuel into the main combustion chamber. Each Merlin engine produces about 200,000 pounds of thrust and is still reusable.

Just starting a rocket engine is a complicated dance that can easily turn out badly if not handled with extreme precision. Sorry, but I don't think there is any way one can equate the complexity of a diving bell with that of a rocket.

Relevant Futurama scene: https://youtu.be/7GDthiBGMz8

It's good if a spacecraft has a little bit of extra margin, at least for atmospheric braking.

A spacecraft has to deal with zero to one atmospheres.

A rocket has to deal with rocket thrust/structural cross-section units of pressure. I'm neither a engineer nor informed about the structure of a Falcon 9, but that number is > 1 atm even if the entire cross-section is structural.

It's debatable whether it was ever fit for purpose at all though.

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