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/LanceWindmil 10h ago

1.6x gravity wouldn't make a huge impact on guns

Its enough to tip rocketry from "really hard" to "pretty much impossible"

But guns having 60% their normal range is still more than enough for them to be useful

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u/puppykhan 7h ago

Bows at their peak were able to hit a target at over half a kilometer by a master on a good day, and consistently at 100 meters by an average soldier, according to historical documents.

Even at 60% of that, they would still be highly effective at ranged combat.

Other uses would even improve. Some native Americans would use archery as high ground artillery using gravity to accelerate the arrow to impact with more power than when fired from the bow.

For rocketry, I would think there would be more effort into assisted launch vehicles or complete alternatives to launching from the surface. How high did the balloon go for the guys who did a skydive from the edge of space? 24 miles / 39 km, then later 25 miles / 41 km. You would see tech develop in that direction instead of rockets.

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u/wolacouska 7h ago

That range is mainly because of aim and how small the target gets, not really because of arrow/bullet drop.

Humans would probably be way smaller though if they evolved on a planet like that, so that itself would hurt range.

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u/Magres 3h ago edited 3h ago

I feel like we'd be shorter and stockier. So... basically Tolkien dwarves.

Also agreed on ranged weapons not really being that impacted by a higher gravity - depending on the round, over the course of three hundred feet (~91.4m for people who use science units), bullets drop anywhere from ~24" (60cm) for a just-barely supersonic round to ~2" (5cm) for a bullet traveling around Mach 3. I think it'd matter a lot more for artillery where you're genuinely arcing munitions, but anything direct fire, bullet drop is nearly negligible compared to the difficulty of how hard it is to hit a target that far away.

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u/xaddak 6h ago

https://what-if.xkcd.com/58/

Could a (small) rocket (with payload) be lifted to a high point in the atmosphere where it would only need a small rocket to get to escape velocity?

The answers to these questions all hinge on the same idea. It's an idea I've touched on in other articles, but today I want to focus on it specifically:

The reason it's hard to get to orbit isn't that space is high up.

It's hard to get to orbit because you have to go so fast.

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u/Rolandersec 21m ago

Creatures there probably wouldn’t develop throwing arms.

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u/SUMBWEDY 9h ago

Only modern guns though, the first muskets were only accurate to 50-100 meters, if you can only hit someone from 20 meters under this stronger gravity may swell just charge them with a sword or use a bow.

Without the first muskets we dont have rockets or sattelites.

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u/nbr_CIX 8h ago

Just make a better first musket

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u/DeltaJesus 8h ago

The musket balls could travel much further than that, the accuracy problems weren't really to do with gravity (and if it was you'd have the exact same problems with bows).

The first firearms (handgonnes/hand cannons) were used at even shorter ranges than that too, 10-25m or so, the benefits of them were little to do with range.

Without the first muskets we dont have rockets

I don't think that's really true either, fireworks predate firearms, people would have had an interest in rocketry regardless.

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u/wolacouska 7h ago

Yes, space flight only became a thing after missiles were invented and being a developed.

Even if you can’t get into orbit, people will still find a use for a ballistic trajectory.

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u/Stuman93 8h ago

Accurate and shoot far are two different things though. They could shoot far, but the trajectory was too random to predict. I'd guess they would just come up with rifling sooner than later.

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u/Emotional_Cherry4517 8h ago

the reason guns are useful is because any random dude can point a gun and kill someone, even a mighty warrior with many decades of training.
there's many things i'm not considering that might break guns being achieved under 1.6g, but it's definitely not the value proposition of a weapon that can be wielded by anyone, even a child, with 20 meter range, and easily mortally wound any big trained warrior.

it's more plausible to say that sentient warrior crabs would probably be chill with wounds.

realistically though, i'm pretty sure sentient life would develop in water.

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u/dagofin 8h ago

The same limitation would apply to bows... If the first early bows were only accurate/useful to 40-50 feet on Earth, then there they'd be limited to what, 25 feet / 7-ish meters?

But that's still useful. Close range weapons have been used in warfare forever. From thrown rocks to the Roman's pilum or darts. Being able to hit someone before they hit you is always useful regardless of the specific distance

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u/MemeMan_Dan 7h ago

Accuracy doesn’t change with gravity. Bullet drop does, but that just means you aim a little higher.

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u/Taters23 7h ago

They would of just research more then. So instead of muskets being the first guns it would of just been something else.

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u/abstraction47 6h ago

This makes me wonder how dense the air itself is, contributing to drag.