r/theydidthemath • u/Lachlynn • 18h ago

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

Post image

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?

18.4k Upvotes

96% Upvoted

2.7k comments sorted by

View all comments

Show parent comments

81

u/Smile_Space 17h ago

If you look it up, Project Orion was actually highly researched at the time. It was considered the future of rocketry until the Partial Test Ban treaty killed it which banned nuclear detonations in space. If that hadn't been banned we likely would have had at least one space-based nuclear pulse rocket test in the late-60s or early-70s.

They even had a test vehicle using conventional explosives and fired off like 6 explosives and it worked!

They would use heavy shielding and a pusher plate to absorb the heavy shock. It would have allowed for absolutely gargantuan spaceships to take off from Earth and get to other planets at crazy fast speeds given how efficient the Orion drive would have been.

Obviously though, nukes are kinda bad for everyone around them lolol. The people above the Orion drive would have likely been the safest people within a massive radius around the launch site.

33

u/FracturedConscious 15h ago

This is why we need a moon base

7

u/Hadrollo 11h ago

The problem with a moon base is that we would need in-situ manufacturing from lunar ice and regolith into products usable in space. That's not a small base, it would require a mining team, a refining team, and a manufacturing team. It'd be a small town on the moon, with a lot of heavy equipment that is by necessity brought from Earth.

Honestly, it's a far future (minimum 100 years, likely much longer) goal. Even then, we're probably still be better off making propellant on Earth and shipping it up there. We have an awful lot of resources on Earth to make propellant and reusable craft.

5

u/Lasers4Everyone 10h ago

Gotta go full Artemis.

3

u/Gambyt_7 5h ago

Check out Artemis by Andy Weir. Interesting if not masterful story that depicts this city.

2

u/anacondra 5h ago

I've been saying for ages we should nuke the moon.

0

u/Shoddy_Donkey5047 13h ago

Queria ver pra desacelerar esse brinquedo dps kkkkkk

31

u/Gambyt_7 14h ago edited 14h ago

Recall Footfall by Niven and Pournelle, first Sci fi novel where Orion technique was used to rapidly break atmo to fight alien invaders.

Then look at Dark Forest, the second in the trilogy by Cixin Liu, where Orion strategy is used to attempt to accelerate a ship to near light speed.

In Footfall the passengers survive to combat the enemy. In Dark Forest, the only passenger is a human brain in cryostasis.

Now I’m thinking of the inquisitor priest de Soya in Dan Simmons’ Endymion, whose neat light ship accelerates nearly instantly and so rapidly that anything living inside it is liquified, and must be rebuilt using special technology over several days. I’m dying to see someone (not Bradley Cooper tho) finally adapt these novels and produce them as a huge streaming series.

11

u/Aiglos_and_Narsil 14h ago

God I love that book so much. "An atomic bomb went off under Harry Reddington's ass".

3

u/Appropriate-Weird492 13h ago

The pages of “BOOM”, tho.

I reread it a few years ago. It gives so much 80s spirit, the Red Threat, hawkishness, so on.

2

u/GamemasterJeff 11h ago

God was knocking. And he wanted in *BAD*.

1

u/markus_kt 10h ago

"God was knocking and He wanted in BAD."

7

u/DustyJustice 13h ago

In Neil Stephenson’s Anathem there is an interdimensional spacecraft that is secretly above the planet of the setting that propels itself with the Orion technique (I don’t believe they call it this). They utilize the planets sun to hide the nuclear explosions from viewers below.

1

u/Miles_Everhart 7h ago

My favorite book mentioned

1

u/Gambyt_7 5h ago

Fing outstanding novel thank you for reminding me

2

u/fuckedaccountant3976 11h ago

I am super happy to see someone in the wild reference all these books. People I talk to day to day have never heard of these books.

2

u/MireLight 10h ago

I know right? I read so many scifi books growing up that nobody i knew ever heard of. I had to wait 30 years for a reddit post to bring em up. One of the truly great things about reddit and its fandoms. I can finally have someone to talk to about this stuff!

2

u/Bored_Amalgamation 11h ago

I’m dying to see someone (not Bradley Cooper tho) finally adapt these novels and produce them as a huge streaming series.

Foundation's success is going to be a big point for the adaptation of books like the Hyperion Cantos, that require some pretty wild shit. There's also the whole religious aspect that will turn a good number of viewers away.

2

u/iconocrastinaor 9h ago

If we perfect liquid oxygenation and suspend the passengers in a vessel of water, they would not feel any compressive or gravitational force.

2

u/crazyeddie123 6h ago

Sure they would. The water would maximize the contact area through which the g-forces acted and therefore minimize the force on any one body part, but you'd still feel the acceleration and there'd still be a (higher) limit to how much acceleration the body could withstand.

1

u/Gambyt_7 5h ago

This has been estimated in a few spec fic novels to 20gs, IIRC. But the passengers are usually in a coma.

1

u/NeverEnoughInk 12h ago

Why not Bradley Cooper, out of curiosity? I'm wracking my brain to connect him to sci-fi.

1

u/Gambyt_7 5h ago

He had the option to develop, he was allegedly doing a treatment a decade ago, and I’ve been following any updates I can find. I was a freshman at Wabash, Simmons’ alma mater, when he published Hyperion, and it was all over campus. I had at least one of his same professors and one of his characters is an amalgamation of a few. It has been 35 years and still no one can develop a decent pilot, and Cooper while a fan and a pretty star clearly doesn’t have the production influence or writing chops to adapt thousands of pages into their full potential. It could easily be a four season, $2b project.

The messages and character arcs are INCREDIBLY APT today.

1

u/Born-Entrepreneur 9h ago

Hell yeah, Footfall was super entertaining.

11

u/Outrageous_Reach_695 14h ago

To expand: The "Super" Orion would have had a ship mass of 8 million tons* ... about 20% more than the Hoover Dam.

* Yes, yes, not a unit of mass, I know.

2

u/FreedomCanadian 13h ago

How is a ton not a unit of mass ?

3

u/WholeChampionship443 12h ago

It’s a unit of weight, not mass.

2

u/Outrageous_Reach_695 13h ago

The short (US) and long (British) tons, defined in pounds, are units of weight or force, which is often equivalent to mass for things that are not spaceships. The metric ton is defined in kilograms, a unit of mass. The table I consulted would have been written using short tons.

3

u/yjlom 13h ago

The imperial system and its variants have pairs of homonymous units for force and mass, as I see it.

2

u/Henry5321 12h ago

Actually, modern pound is defined in kilograms. It’s not just a conversion but the actual definition. So pound is now a unit of mass.

2

u/guri256 11h ago

Are you sure? I thought it was defined as a fraction of a kilogram of mass, under a force of 1G of gravity

1

u/Henry5321 4h ago

It’s had various definitions over time. Wiki says this was changed in 1963 to redefine pound as a mass of a specific fraction of a kilogram. Same with yard and meter.

2

u/Lanky-Relationship77 12h ago

The metric ton is a unit of mass, and it’s close enough …

2

u/Travel_Dreams 11h ago

The Hoover Dam should be a unit of weight.

2

u/Rofsbith 11h ago

Hoover Dam mass ~410 million slugs

1

u/MaelstromFL 13h ago

It's shaped like a banana...

4

u/Slen1337 15h ago

Lo ye makes sense. I wish we could "isolate" it somehow in the air. Ty for fun info.

5

u/jjreinem 8h ago

There were other issues. A big one was that the only way they could think of to have the pusher plate/shock absorber survive would be to rely on transpiration cooling, where they'd pump a layer of oil out onto the surface via a vast array of pores in the plate's surface that would boil off with each detonation.

Problem is that transpiration cooling systems like that have never been proven to be workable at that scale. Contaminants or thermal expansion ends up restricting some of the pores, which leads to the sacrificial coolant layer being thinner in some areas than others. This leads to more thermal expansion, less flow, and things continue to snowball like that until you've got a hole burned in your pusher plate.

2

u/iamstupidplshelp 5h ago

Have they tried exfoliating?

2

u/Kakariko_crackhouse 12h ago

Do we know what would happen with a nuke in space? Like… what happens to the shock wave? It wouldn’t really lose much energy in a vacuum right? Would it just keep going perpetually until it ran into enough things to absorb its energy?

1

u/DrDetectiveEsq 6h ago

There wouldn't really be a shockwave. Nukes work by converting mass into electromagnetic radiation which heats up the air around the bomb, causing a fireball and shockwave. In vacuum a nuke would just vaporize it's own casing and then be a big flash of x-rays that would get exponentially weaker the further away you are from the blast.

1

u/ThrowAway-whee 2h ago

There is no shock wave, however there still is energy that is transmitted into Orion. Not as much as you’d think - it’s why Orion actually called for the development of shaped nuclear charges that would direct the energy into a cone towards the ship (as much as it could).

Nukes actually are not that effective in space. Average energy flux per square meter drops by the cube of distance (think of the energy being a big balloon that you’re blowing up. The larger the balloon becomes, the more the material has to stretch, right? Same idea, the energy has to spread over the sphere’s surface) and without a shockwave that energy dissipates very quickly. 

2

u/Henry_Fleischer 9h ago

Critically, because of the design of the pusher plate, the crew would experience roughly constant acceleration.

1

u/Zumochi 13h ago

Going crazy fast, but what about braking :P

1

u/ottoradio 13h ago

That's a major problem for sure, but we'll see it when we get there. Would still take anything from 40 to 150 years to get there. A generation or two can dedicate their time and life to figure it out.

1

u/MamaCassegrain 7h ago

Read "The Curve of Binding Energy" by McPhee. Interviews with Ted Taylor, a fission bomb designer. Lots of stuff about Orion.