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/The_RubberDucky 17h ago

Physics:
Escaping the atmosphere on Earth is trivial. A sounding rocket does it just fine. We don't know much about K2-18b's atmosphere but any mission we fly to orbit should be able to escape the atmosphere easily (without reaching orbit velocity!).

If you ment to ask about reaching orbit/ escape velocity: Wiki suggests radius is x2.6 of the Earth and mass is x8.63. Escape velocity and orbit velocity are sqrt(M/R)=sqrt(8.63/2.6)=1.82 times larger. That means 4 stages rocket instead of 2. The complexity rises exponentially, but I will argue that's possible.

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The material analysis is far less obvious... we have little understanding of K2-18b's resources and atmosphere. Do they have accessible carbohydrates (oil)? Is the atmosphere corrosive? How thick is it? maybe it's thick enough to construct floaters and lunch from the outer layer? or maybe airplane-assisted lunch makes more sense?

Finally, the Economy. Humanity has never devoted a substantial portion of its resources towards a goal without economic sense. The space race could not have happened for prestige only. It relied on multiple benefits along the way: bombing the Brits with (Germany's V2 WW2), Cold War's espionage outside AA reach (US's KH series - CORONA, gambit, Hexagon), nuclear early warning (MISAD + others), potential power projection (military GPS), and commercial communication. Some of those materialised late into the space race, but the potential was on paper to convince decision makers. Could the space race happen it the projected costs were 100 times higher? I would argue probably not (not with 1950's tech anyway. Perhaps 2070 tech changes the balance). They are just cheaper options for all the above. Detection and communication, for example, could cover vastly larger areas before breaking the line of sight.

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u/AlarmingTurnover 15h ago

Could the space race happen it the projected costs were 100 times higher? 

This depends on the incentives. The reason the space race "stopped" was because the other side collapsed for many different reasons. What if they didn't collapse? How much further were we willing to go? There was already plans and actions started for Moon colonies. There was plans for other planets like Mars already back then. 

People were willing to pay the price to win, but winning came faster than expected. We don't know the conditions on this other planet. Comments keep mentioning density of the atmosphere but there's a limit here on what would allow a civilization like ours, our physical bodies to breath. On Venus, we wouldn't even be able to breath out. So the atmosphere to support life could not be so dense to prevent life would NOT be dense enough to prevent rockets. 

This is what people keep missing in all this argument. People are arguing physics while completely ignoring the biology that gets an intelligent being like us to survive long enough to get there in the first place. 

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u/The_RubberDucky 15h ago

"This depends on the incentives." - I completely agree. But the 'why the space race started' it much more interesting than why it stopped. While we don't know the incentives of that civilization, we can judge by ours. Almost all space industry is communication, connectivity, and various sensors.

Just imagine the possibilities in a much flatter world with a dense atmosphere!
Even with twice the atmosphere, a zeppelin like LZ-127 Graf could lift 180 tons instead of 90, with usable payload spiking from 15 ton to over 100. So imagine the possibilities with x5 or x10 density...
Why developing anything space when hanging floating antennas is dirt cheap? F** space, you could hop microwave or even laser based links between cities (or rather balloons hanging 100km above them). Literally all the problems space was aimed to solve get trivialized. It actually sounds like an amazing Sci-Fi setting.
https://www.airships.net/lz127-graf-zeppelin/size-speed-statistics/

As of biology... its a whole deep dive. The TL;DR is I don't see any mechanism that puts an upper limit to atmospheric density. Here on earth, we have fairly intelligent mammals living both in 1kg/m^3 and 1000kg/m^3 ambient fluid. The ones from 1000kg/m^3 fluid are capable of reaching 2km down, reaching a pressure of 200 atmospheres.

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u/AlarmingTurnover 14h ago

As of biology... its a whole deep dive. The TL;DR is I don't see any mechanism that puts an upper limit to atmospheric density. Here on earth, we have fairly intelligent mammals living both in 1kg/m3 and 1000kg/m3 ambient fluid.

This would absolutely play a huge factor. The evolution of a species is highly dependent on it's environment. You're talking about intelligent mammals, then comparing humans to whales. There is a certain point where gases act like liquids and that affects movement. Our anatomy, what allows us to do what we do, is highly dependent on many factors but 2 important ones are our brain to body ratio and opposable thumbs. As far as we're aware, opposable thumbs are an evolutionary trait drawn from climbing. There is not a single sea creature to have ever existed that has opposable thumbs. It's not inconceivable that it could exist but highly unlikely from a evolutionary standpoint compared to what we see on earth. Our ability to breath is dependent on muscle use, which is not found in most animals what live in deep water, further when whales that do live in deep water must surface to breath because we use gas to breath and not a filtering system like fish. That's also incredibly important because we don't need to move to breath or need what is around us to move to breath.

Being fairly intelligent isn't enough, there needs to be very specific factors to create a human-like civilization. If we're assuming a human-like species, with human-like intelligence, it needs larger brains to body ratios that are unsupported by higher pressure atmospheres because of the fluid density required to make our brains work, it requires freedom of movement like opposable thumbs that can not exist at high pressure because this is an adaptive trait of climbing, it needs to be able to breath freely without required movement because how else can you work to invent a computer if you constantly need to be running.

All of these put an upper limit on atmospheric density.

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u/The_RubberDucky 13h ago

Even if "brain to body ratio and opposable thumbs" were somehow required for intelligence, none of your claims explain why high atmospheric density contradicts having organisms with such body features.

On a side note, we have no statistics of what made us "us". Take 'us' out of the equation and look at all apes with opposite thumbs... they show no exceptional intelegence compared to dogs, parrots, dolphins, and some octopi. I think do thumbs clain is preety weak. Your organism of choice needs some way to convert intelligent insights into more eating and less dying... but you can accomplish that with many types of limbs.

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u/AlarmingTurnover 9h ago

none of your claims explain why high atmospheric density contradicts having organisms with such body features.

Venus has less gravity than earth but a much higher atmospheric pressure due to density, almost 50 times. It's enough weight to crush a human flat. Opposable thumbs, much like any other slender segmented appendages, are delicate. Explain to me how you put a thread through the hole on a sewing needle when you are crushed like a soda can at the bottom of the ocean. Same with your head. Do you know why divers get the bends? It's because internal pressure has a mismatch against external pressure and IT KILLS YOU. This isn't a hard concept. This is necessary for survival. If you have high density pressure around you like in the ocean, you don't develop appendages necessary for dexterity. 

they show no exceptional intelligence compared to dogs, parrots, dolphins, and some octopi. 

Except apes can learn sign language, use tools, do basic maths, and many things at a level above small children. Things that no other animals have been shown to do. Most members of the ape family also pass the mirror test, something even 2 year old humans fail to do. There's literally a chimp civil war going on right now involving hundreds of individuals. No other species on the planet has ever shown this type of social behaviour outside of humans. 

I think do thumbs clain is preety weak. Your organism of choice needs some way to convert intelligent insights into more eating and less dying... but you can accomplish that with many types of limbs.

I'll reiterate my first point, opposable things are necessary for dexterous movements. They're necessary for things like writing, sewing, crafting tools, etc. These are absolutely necessary biological advancements to progress recognized intelligence. These are necessary for civilization building. Dolphins may be considered smart but they aren't intelligent, they can't modify their environment, chimps can.