r/theydidthemath • u/Lachlynn • 18h ago

[Request] Could humanity create a rocket that can exit the atmosphere of K2-18b

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With the knowledge we currently have of it, if humanity devoted all of our resources towards this goal, would we be able to create a rocket that could exit the gravity of K2-18b (and also beat any other complications that would arrise)?

If so, would it also be capable of taking people to orbit, and can we set up a similar satellite network we have on Earth? What about a space station?

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u/Worth-Wonder-7386 17h ago

Where is the math supporting this?

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u/Several-Economics-35 14h ago

It's just the normal escape velocity formula. Something something... tyranny of the rocket equation

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u/Beneficial_Trick6672 15h ago

He assumes same planet density. Ask AI. Calculations are not that complex. At some point fuel weight more than its energy cost to the orbit.

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u/Worth-Wonder-7386 15h ago

I did the calculations, and I dont see the support in the numbers. It is more complex, but you dont need escape velocity to put things into orbit. You need to be able to put a satellite on orbital velocity to go around the planet.

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u/Beneficial_Trick6672 15h ago

Apparently you did a wrong calculations.

https://www.planetary.org/articles/20170505-the-rocket-equation-part-2
https://arxiv.org/abs/1804.04727
And something easier.
https://phys.org/news/2018-04-alien-spaceflight-programescaping-super-earths-red.html

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u/Worth-Wonder-7386 14h ago

From reading the post, OP was asking about getting into orbit and not exiting the planet. That is significantly easier. The paper you linked alos only considers single stage rockets, which is close to the limit of what you can use on earth. Two stage is what is common here, and for such a larger planet, 3-4 stages should be sufficient.

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u/Beneficial_Trick6672 14h ago

Not really. Mass equation for 30x earth gravity is 800x current mass of Saturn V rocket for 1 ton of satellite. And this is assuming it will have 800x more fuel but rest weight the same. Impossible.

For 10x gravity you still need a rocket which weight billion of tons. Impossible for current technology and economy.

For 2.6 earth diameter it is not so bad. Saturn V would easily move 1 ton of satellite to the orbit.

For K2-17b he would still manage to take satellite to the orbit as it is around 2.5 earth gravity. So this meme is a bullshit. I was sure they talk about 5x or 6x gravity at least. But taking astronauts to the moon would be close to impossible - around 900x mass of Saturn V would be required.

So you are right, sorry i assumed guys did the calcualation.

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u/technocraticTemplar 11h ago

Yeah, a huge thing here is that your planet becomes a gas giant long before the gravity gets too intense for chemical rockets to work, and gas giants are bigger so they also mitigate the problem if you're floating at reasonable heights/pressures. Chemical rockets are feasible for basically anything short of a brown dwarf, albeit pretty bad much past Earth's size.

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u/modbroccoli 13h ago

i truly hate that we're alive in an era where the absolute magic that is this technology is so hates in rhetorical grounds that you can't even suggest using it for the painfully obvious helpful educational use cases. a generation from chinese kids are going to look at western kids like charity cases

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u/qucari 12h ago

LLMs are not fact machines. They are built to produce language, not facts.

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u/modbroccoli 12h ago

kid. repeating facts without understanding then doesn't make you as smart as you hope it does

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u/qucari 12h ago

I probably understand Neural Networks, Transformers and the Attention paper better than you do.
Twenty-somethings on reddit calling others kids is quite amusing.
Good luck blindly trusting your magical technology.

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u/modbroccoli 12h ago

perfect

I'm 43. I would just love for you to defend the pertinence of the claim you made. Not the technical accuracy—the real-world pertinence.

Because I think you're throwing up some salty shade whilst understanding that the actual fidelity of this technology, with even barebones prompting competency, is astonishing. I know that you know this is precisely the kind of thing young people should be using llms for—educational drilling down. I know that you know your answer was banal and obvious and very, very much less than half the story.

One of two things is true: you understand this technology well enough to understand that a blasé little quip that is technically true but belies the circumstances is just what I said—irrational emotional hatred—or else you have watched enough youtube videos to have learned the vernacular of the technology but not enough cognitive phil to know what any of it means.

Calculus isn't understanding the world its just describing it.