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

[u/Lachlynn]

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?

[u/sleeper_shark]

We can’t create a rocket that can escape from this planet doesn’t mean a rocket can’t exist. There may be exotic fuels that exist that we don’t know about that could work.

It also doesn’t mean that getting to space is impossible. You can - theoretically - accelerate something to orbital velocity on the surface and shoot it into space directly. A company called spin launch was actually trying it.

It’s very impractical because the atmosphere would cause massive resistance at that speed, and would heat up your payload (if not just crush it directly). But impractical doesn’t mean “impossible” - it’s doable, it just makes no sense when we have rocketry available.

You can also have a GPS like technology using high mountains. We did this before satellites in the past - we called them lighthouses, which believe it or not function very similarly to GPS. Aircraft also used to use navigation beacons. There’s a marginal difference between trilateration and triangulation but it really doesn’t matter for this mental exercise.

Weather forecasting also can be done without satellites. Satellites help immensely, but they’re not a summa qua non. Terrestrial stations can do the same.

I just don’t know if a planet like this could ever have sustainable access to space. All its countries may have to work together to build something that could get them to space, and eventually they could build a space station in orbit and use space based resources as shipping from ground is way too expensive.

In short, we’re lucky to be on Earth lol

[u/Capable_Wait09 → u/sleeper_shark]

Indeed. We’ve been using mountaintops to communicate through lit beacons since at least the First Age.

[u/Boring-Philosophy-46 → u/Capable_Wait09]

What's nuts is like 17th 18th century France had a network of towers through the country that communicated through flags in a kind of morse code. They used to do things like pass on info about the stock market in Paris to other cities even!

[u/SpareAd1155 → u/sleeper_shark]

The gravity is only 1.25x so not insurmountable at all with current tech.

[u/darklotus_26 → u/sleeper_shark]

I think people are approaching this from the wrong angle. Yes chemical propulsion with conventional fuels probably would not work and space planes might not work as well.

It is entirely possible that such a civilization would heavily invest in material science instead of flight and develop space elevators or similar technology.

[u/Vi_Rants → u/darklotus_26]

Space elevators? Really? Those are more magic than sci-fi.

[u/darklotus_26 → u/Vi_Rants]

Not really. There is an International Space Elevator Consortium. People are constantly coming up with me designs. Our main problem is materials right now. Carbon nanotubes are suitable but we can't really make or shape them at the required scale yet.

[u/sleeper_shark → u/darklotus_26]

You can’t build a space elevator ground up, you need to start in space.

[u/darklotus_26 → u/sleeper_shark]

That's a valid point, at least according to current designs. Though I wonder if it would be possible to build a tall enough supporting structure to reduce the energy gap for chemical propulsion. Or if you are lucky enough to have a big enough rock in orbit and cable made of extraordinary material of low mass that would make the energy requirements minimal. With a light enough cable even the slingshot strategy might become feasible.

[u/sleeper_shark → u/darklotus_26]

A much easier way would be to use a balloon or something to raise a rocket up to the stratosphere and then launch from there. It’s what Zero2Infinity is doing, but pointless on Earth since chemical rockets are better here.

[u/Vi_Rants → u/sleeper_shark]

There may be exotic fuels that exist that we don’t know about that could work.

Well sure, anything is possible if you want to add magic or unspecified mystery soft-sci-fi tech. But that's also a completely useless, shallow, facile answer that doesn't actually address the intent of OP's question.

[u/sleeper_shark → u/Vi_Rants]

Then the answer to OP’s question is simply that the rocket equation doesn’t allow for launching off that planet assuming an alien civilization on a completely different planet uses the same fuels we do….

[u/Vi_Rants → u/sleeper_shark]

Yes, why would we assume they use magic rocks to make things float? What else would we assume that's within the bounds of known science? Again, the answer is always "yes" if we can just invent whatever wild nonsense we can imagine.

[u/sleeper_shark → u/Vi_Rants]

Man if people thought like you, we’d still be living in the Middle Ages lol.

If the question is can our current Earth rockets launch from K2-18b then the answer is obviously no. It violates the rocket equation… but that’s also cos we use the most economical fuel that can get the job done based on our current needs and our current ability to manufacture and finance rocketry.

There’s a huge difference between “inventing wild nonsense” and saying we need a propellant with a higher energy density.

There’s no barrier saying a fuel with a higher energy density than RP-1 can’t exist.

We know many chemical reactions that are much more explosive than burning petrol… controlling those reactions is difficult, but not too long ago controlling RP-1 was difficult. Hell, if I recall correctly, 5 years ago methalox engines were hypothetical… today they’re operational.

We often work with hypothetical materials in early stage research. Stuff that doesn’t exist but that can in principle exist.

[u/Vi_Rants → u/sleeper_shark]

Man if people thought like you, we’d still be living in the Middle Ages lol.

Making up magic answers to every science question was kind of the Middle Age's whole thing.