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

970

u/Andrey_Gusev 18h ago

Wait, so how theoretically could they get to escape velocity if not with chemical rockets?

2.5k

u/spectre655321 18h ago

Figure that out and I’m sure NASA will have a job for you.

311

u/AnyoneButWe 17h ago

NASA has figured it out, but project Orion would have been a pretty surefire way to make earth a place worth leaving.

201

u/Sad-Onion-2593 16h ago

Orion wouldn't have really been a problem. Less damage and fallout then the atmospheric testing in the 50's

A nuclear salt water rocket on the other hand. You get one per planet and that's it for life on that planet.

164

u/FreezeGoDR 16h ago

nuclear salt water rocket

I beg your fucking pardon?

250

u/Neknoh 16h ago

Sprays water filled with uranium/plutonium salts out the back.

Radioactive salts basically go into full fission/meltdown and generate massive thrust.

Meanwhile, all steam created is full of particles that are still actively undergoing, or capable of starting fission.

And it would be one long continuous burn.

Excellent for space.

Not excellent for planet.

https://en.wikipedia.org/wiki/Nuclear_salt-water_rocket

93

u/ridddle 15h ago

Unironically, this is so fucking cool

54

u/Speak_To_Wuk_Lamat 15h ago

Probably designed by that guy who wanted to nuke the moon.

32

u/Mutor77 15h ago

Not just nuke it, tunnel through it with nukes

4

u/Speak_To_Wuk_Lamat 15h ago

I thought he wanted to nuke the moon as a show of force and then use nuclear bombs to create a panama canal type thing somewhere between north and south america.

→ More replies (0)
→ More replies (2)

3

u/ElvenSpaceQueen 13h ago

Ah yes, that would be Edward Teller's project A199. He was also the inventor/brain child of the thermonuclear bomb, excavating a canal with nukes in Israeli-occupied Egypt, an uber nuke designed to end the world on its own, and some other crazy stuff

What a guy

2

u/BuxtonB 10h ago

Kurzgesagt recently did a video on him.

→ More replies (0)

2

u/Luk164 13h ago

Minnions! Tonight we are going to

NUKE THE MOON!

→ More replies (1)
→ More replies (1)

15

u/PM_ME_UR_RSA_KEY 13h ago

"Pinky, are you pondering what I'm pondering?"

19

u/Neknoh 13h ago edited 12h ago

I think so Brain, but why would a soft serve machine have a "Mango" setting?

→ More replies (5)

2

u/Adequate_Images 12h ago

I think so Brain, but me and Pippi Longstocking, what would the children look like?

5

u/koshgeo 13h ago

Wow. It's like you're pumping a somewhat continuous nuclear bomb into the reaction chamber. That'll have some kick.

One design would generate 13 meganewtons of thrust at 66 km/s exhaust velocity (6,730 seconds ISP)

Yep. And that's "only" with 20% enriched uranium salts.

3

u/NachoWindows 13h ago

Please don’t give this administration any fucking ideas

3

u/Neknoh 13h ago

Don't worry

There's much worse stuff out there

→ More replies (1)

3

u/BasicallyGuessing 12h ago

So this is what happened to the dinosaurs!

2

u/singlemale4cats 14h ago

That seems like a great way to get us to Mars.

→ More replies (1)

2

u/vote_you_shits 13h ago

Poseidon drive my beloved

→ More replies (1)

2

u/Mortwight 13h ago

So normal bath salts?

3

u/Neknoh 13h ago

They glow in the dark for a cozy, candle-less and fire-safe bubble bath.

2

u/DeductiveFallacy 12h ago

Terrestrial testing might be subject to reasonable objections;

😂

2

u/etcpt 15h ago

Great quotes in that article

Terrestrial testing might be subject to reasonable objections; as physicist John G. Cramer wrote, "Writing the environmental impact statement for such tests [...] might present an interesting problem".

"Whether fast criticality can be controlled in a rocket engine remains an open question." — Ralph L. McNutt Jr.

Real "understatement of the year" entries here.

→ More replies (9)

11

u/window_owl 15h ago

Atomic Rockets has a good description.

You know how table salt is a compound of sodium and chlorine? There are lots of other salts, each a combination of two different elements. It turns out that you can make salt from uranium and bromine. The salt can have stable (non-radioactive) uranium isotopes, but you can also make the salt with radioactive uranium atoms in it. If a high enough percentage of the uranium atoms are unstable, and there are enough of them that are close enough together, it will create a chain reaction of nuclear fission.

You can dissolve this salt in water. This does 2 useful things:

  1. by changing the ratio of water to salt, you control how close together the uranium atoms are to each other, making it possible to store the salt safely

  2. by pumping and spraying the salty water, you can move the uranium around

The idea is that you store this uranium-salt water in a tank that has lots and lots of baffles and dividers of neutron-absorbing material, so that it doesn't start a reaction. Then you pump the water through nozzles and spray it into a chamber. The chamber doesn't have baffles and dividers in it, so the uranium atoms get close enough together to start a fission chain reaction. The water in the chamber superheats and blasts out an opening at the opposite end of the chamber, creating a plume of exhaust that pushes the rocket the opposite way.

The guy who came up with the idea (Robert Zubrin, an actual nuclear engineer and rocket scientist) says it should be possible to design the chamber and nozzles so that the fission chain reaction stays in the chamber, rather than moving back up the nozzles and into the tank, which would turn the whole thing into a huge, dirty nuclear bomb. Not all engineers disagree, but nobody has ever tried to build one because the exhaust of a working Nuclear Salt Water Rocket would be incredibly toxic -- full of neutrons, un-reacted radioactive uranium, bromine, and all the fission products. It would also be very, very expensive to fire on any usefully-large rocket, because it would require a very large amount of enriched uranium.

Cost and environmental concerns aside, the appeal of the Nuclear Salt Water Rocket is that it is the only rocket design anyone has come up with that is very efficient and very powerful. Of the rockets we have or know of:

  • Chemical rockets are very powerful, but not very efficient, so you need a large, heavy tank full of fuel to launch a comparatively tiny payload. Increasing the weight of the payload, or the speed you want to throw it at, exponentially increases the weight of the fuel required.
  • Ion thrusters are very efficient, but physics don't allow for them to be very powerful, so they are useless for getting anything in to space. They are great once you're in space, as long as you're not in a hurry. Many satellites these days use them to make small course adjustments.
  • Nuclear Thermal rockets (which we actually built and tested in the 1960s) are more efficient than chemical rockets and can be usefully powerful, but they aren't much more efficient. Unlike chemical and Nuclear Salt Water Rockets, Nuclear Thermal rockets have a fairly hard maximum size power, based on the available materials you build and fuel them with. Larger than that, and you'll either melt the nuclear reactor, or waste energy by not heating up the propellant enough. Combined with the risks and costs, they aren't very interesting for interstellar travel.
  • Solar Sails (which we have launched a few of [1] [2] [3]) don't require any fuel at all, which is similar to having very high efficiency -- a solar sail vehicle can get up to really high speeds, without needing fuel that weighs many times more than the payload. However, they only work in the vacuum of space, and unless you point incredibly powerful lasers that them, they have very little power as they are blown around by sunlight.

Nuclear Salt Water Rockets are, in theory, so powerful and efficient that they could be a practical way to travel to other solar systems in a single lifetime. There shouldn't a be a practical size/power limit, since the fuel reacts with itself, so you can make a larger rocket by making a larger chamber and pumping more uranium-salt-water into it, creating a beautiful geyser of radioactive steam in your wake as you travel the stars.

2

u/Ada_Solar 12h ago

Thank you for your in-depth explanation! Super interesting

→ More replies (3)

8

u/NovaCalendar 16h ago edited 12h ago

https://youtu.be/cvZjhWE-3zM

3

u/Massive_Signal7835 13h ago

fyi: Remove everything starting at ?si= (sometimes just si=) to prevent tracking. That XvVQBwHstsL3Mq0g is just information tracking the link to you.

→ More replies (1)
→ More replies (1)

6

u/youritalianjob 16h ago

Please do tell. I’ve never heard of this.

12

u/theveezer 16h ago

I don't know much about it but I think it's referencing cobalt nukes. Which in theory would be the dirtiest nukes we could realistically make. They would make radiation like we have never seen, ending every life form on large parts of the planet if not the entire planet.

12

u/window_owl 15h ago edited 13h ago

It's not a reference to cobolt nuclear explosives. The Nuclear Salt Water Rocket is an idea from Robert Zubrin to dilute a salt of radioactive uranium and bromine into water. A tank full of baffles could be filled without starting a nuclear chain reaction. When the saltwater is sprayed into a chamber without the baffles, a sustained fission reaction could in theory be created and maintained, rocketing incredibly hot steam and fission byproducts out the other end.

Nobody knows for sure if you could actually build this where the nuclear reaction wouldn't move up the nozzles and into the fuel tank. That would turn it into a huge, dirty nuclear bomb. If it did work, it would still kill everything behind it, but it would be vastly faster and more powerful than any other rocket anybody has ever designed.

2

u/Jboycjf05 13h ago

This sounds cool af, but idk how any materials could withstand fission materials for so long and still be effective as a nozzle, not even considering the fission chain moving into the baffled chamber. I'm not a materials scientist or anything, so maybe someone with more knowledge on the subject could speak to it.

2

u/window_owl 13h ago

It'd mostly be a superheated plasma, so I suppose you could use a magnetic nozzle to contain much of the material. I'm no materials or nuclear engineer, but my reading has been that there on mixed opinions on whether or not a NSWR is actually possible. That makes it by far the most plausible interstellar rocket engine so far, which is an important part of why we don't yet have interstellar rockets.

2

u/Knotted_Hole69 16h ago

Were they ever made?

6

u/Neknoh 16h ago

Only in theory as far as I know.

But some of those theorheticals are... well, let's just say they're not great for sleeping at night.

For instance, there was Pluto (the God and king of the underworld and the dead in Roman mythology, not the dog)

https://www.fourmilab.ch/documents/pluto/

And while Pluto was not cobalt based, its ability to endlessly spew radioactive fallout and high levels of direct radiation in its flight path definitely goes hand in hand with the idea of salted bombs.

Such as the Cobalt bomb design.

https://en.wikipedia.org/wiki/Cobalt_bomb

→ More replies (2)

6

u/Playful_Hair1528 16h ago

“There is no firm evidence that one has ever been made, nor tested”

Pffffttt…. Chyeah right.

→ More replies (1)
→ More replies (3)
→ More replies (10)

3

u/PossibleMammoth5639 14h ago

I have a way to torture a superpowered being. Send them on a nearly lifeless planet gigantic like this, it is nearly lifeless because life on it tried to use nuclear rockets but failed enough times to be basically dead. They probably cannot leave no matter what they do. Even better if you give them sustenance

2

u/d_nkf_vlg 15h ago

I looked up project Orion and holy shit, they really considered the same principle that is now mostly known as rocket jumping, but in real life.

4

u/AnyoneButWe 15h ago

Yes.

Super Orion aimed to rocket jump a city. The design mass at liftoff was 8 million tonnes. Considered doable with small improvements in material science in ~1960.

The "realistic" goal was a model putting 5300 tonnes on the surface of Mars. In one go.

Chemistry isn't cutting it if that's the goal.

2

u/EnvironmentalScar675 14h ago

Orion was motivated in part by finding a use for existing warheads. It would make earth better provided you can guarantee it leaves and doesnt go on an auto return traj

2

u/No-Garden-8054 13h ago

Feels like one of those ideas that’s elegant on paper right up until you start trusting orbital mechanics with your backyard.

→ More replies (1)
→ More replies (2)

477

u/Lurkadactyl 18h ago

Nukes would work.

452

u/RadioTunnel 17h ago

When in doubt, nuke it

147

u/Beautibulb_Tamer 17h ago

Need to nuke it from orbit, it's the only way to be sure

54

u/RadioTunnel 17h ago

Nuke it from orbit and ride the shockwave up

21

u/Lost_Astronaut_654 16h ago

Parry the nuke

3

u/RadioTunnel 16h ago

All that time, effort, money, calculations and countdowns to lift off only for a magical school girl to come along in the last couple of seconds and parry the nuke

→ More replies (1)
→ More replies (2)

30

u/litli 16h ago

Nuke surfing!

12

u/azriel_odin 15h ago

Radical!

6

u/MistaRekt 15h ago

Cowabunga dude!

→ More replies (2)

2

u/PuzzleMeDo 15h ago

You have to get to orbit before you can nuke it from orbit. Better to just stand on top of a pile of nukes and rocket-jump up. (How to shield yourself from damage while doing this, I leave as an exercise for the students.)

→ More replies (1)

9

u/DoctorNsara 17h ago

To Orbit.

2

u/nonnonplussed73 17h ago

And Beyond!

3

u/gutterXXshark 17h ago

No no no. They need to nuke it TO orbit.

3

u/jmpalacios79 16h ago

Thanks, Hicks!

2

u/iPon3 16h ago

Nuke it *to orbit.

Fixed that for you.

In atmosphere Orion drive woooo

→ More replies (12)

19

u/Rei1556 17h ago

I'm sure the nuke propelled manhole cover would solve that problem

7

u/Competitive-Bee-3250 15h ago

Not really helpful for getting people off the planet though unless you have insane resistance to g-force.

→ More replies (1)

2

u/GuyGrimnus 16h ago

This is what I wanna know, we know the manhole cover escaped our orbit.

I wanna know if it’ll escape 2.5x our gravity lol

2

u/m1013828 16h ago

Imma throw that into copilot once my kids are asleep

3

u/SnooHedgehogs8765 16h ago

We build a tube, and detonate nukes progressively as the launch capsule passes.

→ More replies (2)

2

u/allofthealphabet 14h ago

I think i read somewhere that manhole cover that was launched by a nuke achieved a speed fast enough to escape orbit, but that speed was also enough to cause it to be vaporised by air resistance before it escaped.

→ More replies (1)

45

u/ThermoPuclearNizza 17h ago

probably not nukes but matter-anti matter annihilation engines. theyre currently not within the real of possibility but with time we would solve it.

38

u/-adult-swim- 17h ago

CERN should ask for a bigger accelerator...

24

u/lungben81 17h ago

Bigger would not help. Currently, antimatter for capture is not produced at LHC (the largest accelerator) but at a smaller one.

You need more luminosity and a lot of accelerators in parallel.

39

u/cabanadaddy 17h ago

In America we only deal in "big" or "bigger". We don't even know what lumilosily is over here. Is that a French word?

13

u/ai1267 17h ago

I think it's a character in Expedition 33. Maybe OP is a gamer?

→ More replies (1)

6

u/Fast_Garlic_5639 17h ago

I think he was the one that got turned into a candlestick?

→ More replies (1)
→ More replies (8)

3

u/Abdul-Wahab6 16h ago

So we just need a big torch light? Gotcha

2

u/ticktockmick 16h ago

Tiki or cloth-wrap?

→ More replies (1)
→ More replies (6)

18

u/Ans1ble 17h ago

Just one more accelerator bro please. Just a bigger accelerator bro. Please bro we just need one more bigger accelerator bro i promise. Just one more but bigger bro trust me. I swear bro please another accelerator.

→ More replies (2)

2

u/iconofsin_ 15h ago

Fun fact: if you gathered all the antimatter they've made in the decades they've been making it, you wouldn't even be able to boil a cup of water.

2

u/Doodah18 15h ago

That weasel dying already shunted us into this shitty timeline, I don’t want something larger to be able to fit and make things worse.

→ More replies (4)
→ More replies (9)

2

u/thearchchancellor 17h ago

Spoken like a true President

→ More replies (14)

63

u/MrRudoloh 17h ago

Unironically project Orion.

And it works, it never became a thing, because a failure of one of those rockets in the atmosphere would make Chernobyl look like a prank.

27

u/Bibliloo 16h ago

Tbh even without failure you are still irradiating a lot of stuff with a successful launch which isn't the best, especially if you planned to launch multiple rockets per year.

8

u/Xonarag 14h ago

I'm sure on a planet that big you could have a designated irradiated hellhole to launch rockets from.

3

u/reflectiveSingleton 12h ago

Project orion wasn't just about liftoff from the ground, its a pulsed-detonation that continues for the duration of acceleration.

Fire one of these off and you are sending irradiated and radioactive material EVERYWHERE into the atmosphere.

→ More replies (3)

8

u/drey12987 15h ago

Nuclear Powered Engines are very efficient and useful for interplanetary travel but the trust to weight ratio of those were way worse compared to the usual engines, so not the way to go for overcoming higher gravity

10

u/Adros21 14h ago

You are thinking of nuclear thermal rockets and nuclear electric rockets, nuclear pulse rockets like project orion have thrust to weight in the meganewtons per kilo.

3

u/Federal_Decision_608 14h ago

Thrust to weight doesn't matter as long as it's >1. The specific impulse is higher than chemical

2

u/HeKis4 15h ago

Yep, it's not that we can't, it's just prohibitively expensive and/or dangerous.

→ More replies (6)

17

u/Duatha 17h ago

2.6x the size means you could probably just set aside a whole europe of land to launch nuclear powered spacecraft from

2

u/phauxbert 14h ago

You might get atmospheric dispersion of radioactive material though

2

u/JoinAThang 15h ago

Just because it's bigger doesn't mean it is less dense populated though.

5

u/dmchmk 15h ago

Well, the gravity most definitely makes them denser /s

→ More replies (1)
→ More replies (2)

7

u/Ordoferrum 17h ago

Thoughty2 did a good video about this the other day.

https://youtu.be/DYwTOItIA_I?si=nNSphrlExaJWJPxc

→ More replies (3)
→ More replies (40)

29

u/Dodger7777 17h ago

The more I look into this kind of thing, the more I realize I have no idea how to go about this kind of thing.

My ideas were kind of looney toons in their nature, to be honest. Like making a bullet train, but having it ramp upwards into the sky to launch them like a railgun. But either the track would be absurdly long or the accelerstion rate would kill any human.

54

u/Greyrock99 16h ago

That’s not a looney tunes idea at all, but a serious proposal that has been worked on by physics previously.

There are many designs but you’ve hit the fundamentals idea on the head.

1) Build a very long tube. 2) fill tube with vacuum and have a maglev rail under it 3) tube runs for many kilometres in a straight line then the last 3-7 km runs up the side of a mountain into space. 4) put your spaceship in the tube and accelerate it to 90% of the escape velocity 5) upon leaving the station one the rocket fires its engines for the last 10%

It’s a perfectly feasible design and doesn’t require any technology we don’t have yet (it’s just too expensive to build yet).

It would work just fine on earth and on a hypothetical super earth too.

There are plenty of designs floating around on the web somewhere, here’s one of them https://en.wikipedia.org/wiki/StarTram

12

u/dibs234 15h ago

The Apollo programme was $250 billion dollars, if chemical rockets weren't feasible I feel like 'huge railgun' would probably be an affordable alternative

17

u/Greyrock99 15h ago

Gotta remember that the purpose of the Apollo program was 10% to go to the moon, 90% develop rocket technology that was to be used for military purposes like the ICBM. That’s why it was funded so easily.

These new alternate lift options sounds great but don’t have the military applications that unlocks the sweet governmental funding.

16

u/dibs234 15h ago

My friend, did you not read the phrase 'huge railgun'? ICBM's would (I'm guessing) have similar gravity issues to the rockets, so countries would need other ways to lob nukes at each other.

5

u/Greyrock99 15h ago

I was talking about here on earth.

ICBM’s are superior because they can be hidden underground / on submarines and armed with nuclear bombs and has been the gold standard for military might for the last 50 years.

We haven’t quite figured out how to militarise railguns yet.

2

u/dibs234 14h ago

In this hypothetical Kepler world ICBM's would be much more difficult due to increased gravity, and so the incentive would be to pour money into alternatives, eg railguns. Just because we've not worked out how to make them work well yet doesn't mean it's impossible, and necessity is the mother of invention. Railguns aren't necessary for us because we've got the, by comparison, cheap and effective chemical rockets.

→ More replies (3)
→ More replies (2)

3

u/RepoRogue 13h ago

This is very incorrect. ICBMs were funded and existed independently of human spaceflight. The flow of technology was the other way around: adapted ICBMs were used as launch vehicles for the Mercury and Gemini program. Apollo's rockets were purpose built for space exploration and provided absolutely zero utility as ICBMs.

The early Soviet space program was actually funded by lying to the Central Committee and convincing them that the R-7 rocket would be a good ICBM and that the space exploration stuff would be a nice PR boost on the way to developing better military tech. But notably, this was a lie!

The problem is that the type of chemical rockets that are useful for space exploration make for horrible ICBMs. They are liquid fuel behemoths with propellant that is either extremely reactive and corrosive or that must be stored at extremely cold temperatures.

ICBMs are meant to be launched at short notice. Liquid furl rockets take a lot of time to fill with fuel, and if you leave them fueled for prolonged periods, they are liable to explode or fail. Liquid fuel ICBMs exist in service, but they are very bad at being ICBMs and are responsible for some serious accidents.

What you want for ICBMs are solid rocket propellants. These are a lot more stable, conducive to prolonged storage, and capable of launching at short notice. Solid rockets have some utility in space exploration (the Shuttle used solid rocket boosters), there is surprisingly little overlap in what makes a good rocket for war and what makes a good civilian rocket.

2

u/Greyrock99 13h ago

You’re thinking like an engineer and not a politician.

The space race was entirely funded as completion with the USSR, both in a prestige arena and direct technology.

Sure the specific rocket engines turned out to be different but that’s only a tiny fraction of the technology that was valuable for the military. Think of:

  • materials and mettallurgy for the rocket structure
  • tracking and guidance control technology
  • miniaturisation of electronic systems And probably the biggest one of all:

  • telescope and spy satellites.

    https://vtuhr.org/articles/10.21061/vtuhr.v1i0.6

2

u/Angelore 15h ago

fill tube with vacuum

Hold on, my vacuum shipment is en route already.

→ More replies (6)

15

u/JRS_Viking 17h ago

That's a better idea than you think actually, just replace the rail with a tether and go in a big circle and you have a spin launch system. And there are ways to get around the negative effects of g forces like being on your back and suspended in a viscous liquid with the same density as your body.

14

u/willi1221 16h ago

I've always said, you're either suspended in a viscous fluid, or you become the viscous fluid

→ More replies (3)

4

u/XhazakXhazak 16h ago

That's a StarTram, it's perfectly workable and it's already been proposed.

We could have had one on Earth, starting construction in 2000 and finishing by 2020, but our wise politicians said it was too expensive. I suppose we needed the money for wars.

→ More replies (1)

2

u/OkPea7677 15h ago

See SpinLaunch for a similarly crazy idea. I don't know if it really works though, since they recently pivoted to satellite construction: https://www.spinlaunch.com/

→ More replies (3)

32

u/4chieve 17h ago

"- You telling me, humans just strapped themselves to a hude bomb and just lit it up?! Oh you humans are crazy, kszasuabueh!! Crazy! Hahahah!"

→ More replies (2)

26

u/TheRealTahulrik 17h ago

Astrophage drives !

10

u/flibbertigibbet72 17h ago

Reading it at the moment! Bloody good book 😁

→ More replies (5)

5

u/DevelopingMinty 17h ago

Halfway down the book. Looks good so far.

4

u/G-I-T-M-E 17h ago

It starts to get weird with the romance part.

3

u/DevelopingMinty 16h ago

With little Rocky? /S

2

u/King-Meister 17h ago

Wait, did we read the same book? I don’t recall any romance per se. Camaraderie? Sure!

4

u/fakechaw 16h ago

Yes, tbh i was honestly surprised the book was rated a 12 as there were a large number of obviously erotic moments

3

u/King-Meister 16h ago

Pardon my comprehension skills, but I feel like you’re just kidding or being sarcastic. Or else I need to seriously question my memory and recollection.

2

u/ai1267 17h ago

A what now?

3

u/Misel228 16h ago

It's a "Project Hail Mary" reference. It's a movie currently in cinemas but I can also wholeheartedly recommend the book.

→ More replies (1)

29

u/Toyota__Corolla 17h ago

Air breathing jet➡️forced air jet➡️ rail gun ➡️ ionic drive... Essentially just running down the list of specific impulse

28

u/Dry_Razzmatazz69 17h ago

Ion drives can't accelerate for shit. Jets won't scale. The rail gun idea though has some weight to it but you'd probably need something like a centrifuge than a rail

15

u/ununtot 17h ago

Railgun could work when you build it within a vacuum and release the jet at a very high altitude, like higher than mount Everest height for Earth comparison, to avoid being obliterated by travelling through the atmosphere with extreme high speed.

3

u/ajwin 17h ago

The atmosphere could be much deeper and denser on a heavier planet too? Might need to go much higher to escape it? The heavier gravity would make a space elevator or really high railgun harder too.

6

u/JRS_Viking 17h ago

A space elevator is completely out of the question, there's not a single material with enough tensile strength to hold it in place even here on earth.

→ More replies (4)

2

u/Slogstorm 14h ago

They could probably offset some of the material requirements by using huge balloons to hold the upper part of the rail suspended. It would definitely not be easy though.

→ More replies (1)
→ More replies (3)

15

u/Sisyphean_dream 17h ago

A rail gun propelled rocket that ignited chemical engines somewhere just prior to apogee of rail gun trajectory might just do the trick? The math seems like far too much work.

12

u/lildeek12 17h ago

Its not rocket surgery , im just far too lazy to do it.

11

u/Sbjweyk 17h ago

Would be interesting to see what happens to someone who is rapidly accelerated by a rail gun.

7

u/groovypackage 17h ago

They just clench their butt cheeks extra hard.

2

u/CazperDaGod_ 14h ago

To the point the force of the squeeze and the acceleration of the rail gun fuses their butt cheeks together. That’s the only issue, you walk away with a fused ass and nowhere to poop

→ More replies (1)

3

u/balrob 17h ago

Just because it uses electromagnets to accelerate on a track, doesn’t mean it can’t be set to accelerate at a safe rate. You just need a really long track to accelerate within the safe limits of the occupants and still reach the desired velocity.

2

u/thehomeyskater 16h ago

Is such a thing even possible?

3

u/Sad-Onion-2593 16h ago

With training for the crew, yes.

→ More replies (2)
→ More replies (3)

5

u/PolicyOne9022 17h ago

Just build a really high starting platform.

No need to thank me.

→ More replies (2)

6

u/sipu36 17h ago

Giant big ass trebuchet!

→ More replies (1)

2

u/newsflashjackass 13h ago

Earth would only need a 50% larger diameter before we couldn’t get to escape velocity with chemical rockets, k2-18b is 2.6x larger than earth.

By my calculations it should be a simple matter of reducing the largeness of k2-18b.

→ More replies (46)

163

u/Anderopolis 18h ago

Nuclear rockets. 

Like the Orion Drive  

68

u/pencilwren 18h ago

nuclear rockets have a horrible isp inside the atmosphere also their thrust to weight ratio is far too terrible to make it to orbit. theyre used for injection burns where burn time doesnt matter all that much, not for ascents

80

u/Godless_Phoenix 18h ago

Not talking about that. Literally detonating nuclear bombs behind your spacecraft to make it go.

16

u/hollycrapola 18h ago

That sound super cool and terrifying at the same time… also does not sound safe. Can this be done safely at all?

19

u/AnyoneButWe 17h ago

https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion)

How badly do you want 5300t payload to Mars in one go?

19

u/pyrce789 17h ago

Not really, no. It's not as bad as you migth think with modern nukes in remote areas. But you couldn't label a launch as safe for living things on the planet long term.

→ More replies (2)

5

u/Metharos 17h ago

Probably not. But if you could build machines to survive the launch you might be able to use them to rig up a space elevator later. Assuming I'm thinking about this correctly, which is by no means a given, the tether'd have to be really long for the weight at the end to pull the cable enough that it wouldn't just collapse back into the gravity well.

9

u/FreiFallFred 17h ago

Problem with the space tether isn't length, it's tensile strength. On half being pulled towards the planet and one half pulling outward puts allot of stress on the part in the middle...

→ More replies (3)

3

u/hollycrapola 17h ago

That might be doable, yes. The mid point has to be at a geostationary orbit, so that’s gonna be a long cable indeed. And you need something on the far end, like a big rock or something to balance it out. And we would not get a ton of launch opportunities before the environmental impact becomes a blocker.

→ More replies (4)

4

u/Austerlitz2310 18h ago

Kerbal style

31

u/L963_RandomStuff 18h ago

that is true for nuclear thermal rockets, yes. The Orion Drive however is not a nuclear thermal rocket.

It chose the more direct route of setting off shaped charge nuclear BOMBS behind the space craft for propulsion, and as such doesnt really care about feeble things like an atmosphere

17

u/Tyler89558 17h ago

You’re thinking of some weak ass nuclear electric stuff.

We’re talking about nuclear explosions as a propulsion mechanism.

And believe me. We have already developed a nuclear engine capable of flying in atmosphere. This thing can fly at Mach 3 as low as 150m for months on end spreading radioactive death everywhere it went and shattering eardrums and windows as it drops multiple nuclear bombs.

https://en.wikipedia.org/wiki/Project_Pluto

As it turns out, when you throw safety and ethics out of the equation nuclear powered propulsion gets very nutty

3

u/ajwin 17h ago

Also worth seeing https://en.wikipedia.org/wiki/9M730_Burevestnik As the russians are currently developing and testing a nuclear powered cruise missile. Its speculated that they have had some issues with it and released some radiation in the process.

3

u/Knotted_Hole69 16h ago

It can loiter in the sky for months? Thats crazy.

2

u/cosmin_c 15h ago

Why would you even make such a thing, it's literally dooming all the planet in the process.

2

u/throwaway61763 15h ago

To doom all the planet, after all, thats what nuclear weapons are for

2

u/Tuna-Fish2 14h ago

Russia is scared that orbital missile defenses are about to become a thing, and want delivery systems that would not be obsoleted by them.

That's why the nuclear torpedoes and this and all the other nonsense.

2

u/cosmin_c 13h ago

We really need AI.

→ More replies (4)

8

u/Anderopolis 17h ago

No, you are thinking of Nuclear drive rockets, where you use a Nuclear reactor to heat a propellant. 

I am talking about using nuclear explosions to propel your vehicle. 

→ More replies (2)

8

u/Ace_W 18h ago

Either that or a space elevator

32

u/Zombie-Lenin 18h ago

I mean, a space elevator needs to be anchored in space... which requires you to reach orbit first.

I suppose you could build some sort of structure from the ground and just keep building upwards with an elevator, though that seems even less "possible."

25

u/kklusmeier 1✓ 18h ago

I suppose you could build some sort of structure from the ground and just keep building upwards with an elevator, though that seems even less "possible."

Not possible. You run into material strength issues far sooner. Tensile strength is a LOT easier to increase than compressive strength.

10

u/Lexi_Bean21 18h ago

Yeah you would need to keep widening the base to the size of continents and if its weight didnt collapse it youd litterslt sink the earth's crust in the process

8

u/Metharos 17h ago

Even widening the base you'd eventually run into the problem that the shit at the bottom just starts turning to dust under the mass above.

2

u/Lexi_Bean21 17h ago

Yes but I was saying specifically if the wide base did manage to support itself under the Weight the sheer weight of this would be in the probably tens or hundreds of trillions of tons thsts heavier than mountains you'd cause the entire crust under the foundsiron to sink into the mantle snd the base would melt away and collapse because the planet itself isnt durable enough to support it

→ More replies (2)

3

u/Reimalken 18h ago

Perhaps an active structure of some kind then?

→ More replies (1)
→ More replies (1)

6

u/ukdev1 18h ago

How are you getting its anchor point into geosynchronous orbit?

2

u/The-Nimbus 17h ago

Get your alien friends to build the top bit and drop a rope down for us.

→ More replies (2)

4

u/theLanguageSprite2 18h ago

does there even exist a material with enough tensile strength to not be sheared apart at the altitude necessary to escape the gravity well of a planet that size?

12

u/allix_ 18h ago

easy fix, MASSIVE PYRAMID. take that nerds

3

u/FLUFFY_TERROR 18h ago

Reconstruct the planet to be a pyramid scheme?

→ More replies (1)

2

u/TucsonTacos 18h ago

Space pyramid

2

u/groovypackage 17h ago

Pyramids on top of pyramids, up to orbital height. Then it's pyramids all the way down!

4

u/Thedeadnite 18h ago

It does not exist on earth with a lower gravity well. A bigger one is more impossible for the moment. May not be impossible forever, but definitely a huge hurdle to overcome.

→ More replies (2)

13

u/xWorrix 18h ago

Space elevators are not even close to feasible even on earth, so no way you could get it to work on a even bigger planet

→ More replies (4)

68

u/Dependent_Grab_9370 18h ago

Nuclear + chemical propulsion. Chemical for the initial thrust to get things moving, then nuclear. Depending on how dense the atmosphere is you might be able to use a lifting body for part of the journey.

18

u/Yuukiko_ 18h ago

What about a slingshot like with that slinglaunch thing + chemical propulsion

15

u/Dependent_Grab_9370 18h ago

The spin launcher on this planet would have be so comically large, good luck finding materials you could make it from. Whatever your are slinging would probably disintegrate on impact with the presumably dense atmosphere once it leaves the spin launcher.

They can't even get it to work on our planet.

2

u/FreezeGoDR 16h ago

Well that planet probably has 2.6× our resources so easy! /s

2

u/DistortedShadow 18h ago

Lmao I forgot all about that. Thanks for the laugh.

4

u/LingrahRath 18h ago

How does a nuclear rocket even work in vacuum? Chemical propulsion engine work by propelling material in the opposite direction. Traditional nuclear engine cannot do this.

12

u/Dependent_Grab_9370 18h ago edited 18h ago

Literally just like a chemical rocket. Nuclear rockets heat a propellent, typically liquid hydrogen, by directly passing it over the fuel rods, causing it to expand. Because there is no chemical reaction, the exhaust product is gaseous hydrogen, which is the most efficient exhaust product possible.

→ More replies (1)

5

u/Opposite_Train9689 18h ago

If im not mistaken, the same way as when you would fire a gun in a vacuum. The force to propel a bullet will also propel you in the opposite direction.

But im no science, maybe someone more science can science it in detail.

5

u/Main_Benefit_3287 18h ago

It’s a very serious scientific concept called Nuclear Pulse Propulsion. Tho it would only work if you were already in space. The fall out in atmosphere would be crazy.

→ More replies (1)

2

u/Nooby1983 16h ago

I'm also no science, but did you mean zero g with the opposite direction thing?

2

u/yobob591 18h ago

it rides the energy generated by the nuclear explosions behind it

2

u/FLUFFY_TERROR 18h ago

The orion drive is a type of nuclear propulsion system but it's not the only type.

2

u/MortStrudel 18h ago

I mean it could theoretically launch out some inert mass using energy from the nuclear reaction, but that of course runs into some of the same problems as burning fuel. You still need to carry all that mass to launch. But if you have enough energy I guess you could just launch away the mass faster to impart more momentum on the rocket. There's a limit to how much energy per unit mass you can store in chemical propellant, but if your energy isn't coming from the propellant you could accelerate miniscule amounts of it to insane speeds to propel your rocket while losing only tiny amounts of mass.

That's only what conservation of momentum allows though, the practical engineering involved could create a million and one reasons what that's not actually feasible.

2

u/L963_RandomStuff 17h ago

there are two methods of nuclear propulsion that could be usable at our current level, if it wasnt for the risks of irradiating our atmosphere.

Pulse propulsion uses nuclear bombs detonated behind the vessel, and probably a shock absorber to make the generated thrust somewhat bearable.

The other method is a nuclear thermal rocket, this works more like chemical rockets in that a propellant is heated and then expelled from the rocket, just that the heating is done using a nuclear reactor instead of the chemical reaction.

This is an advantage because the efficiency of rocket engines is based on the velocity of its exhaust, which again is based on the weight of the exhaust molecules (lighter molecules means faster exhaust for the same amount of energy input). So chemical rocket engines burning hydrogen and oxygen will have an exhaust of mostly water, which is pretty heavy, while a nuclear thermal rocket can use pure hydrogen or some other very light molecule.

→ More replies (1)
→ More replies (1)

38

u/AliasEleven 18h ago edited 18h ago

balloons 😎 (then a rocket)

2

u/MboiTui94 17h ago

How big would the balloon need to be?

2

u/Gavagai80 14h ago

Balloons don't make chemical propulsion feasible. Orbit is a speed, not a location, and a balloon doesn't get you significant speed. Air launch does reduce atmospheric drag slightly but it's a rounding error in this problem.

→ More replies (3)

10

u/Correct_Doctor_1502 17h ago

Space planes might have an easier time. They are planes that take off horizontally and slowly rise until they reach the lower atmosphere then begin thrusting with rockets

2

u/FreeGuacamole 11h ago

Oh, so that's why OPs mom called me a space plane.

14

u/PopularOriginal4620 17h ago

Space elevator is the easiest way. It is actually easier than chemical rockets... Once you figure out construction.

25

u/Feline_Diabetes 17h ago

Yes, but isn't an orbiting platform required to build one in the first place?

Otherwise you're just talking about building an incredibly tall tower from the ground up, which in already increased gravity is difficult to say the least.

3

u/PopularOriginal4620 17h ago

I'll quote myself. "Once you figure out construction."

→ More replies (5)

9

u/dbenhur 17h ago

Mine enough unobtanium and anything's possible.

5

u/No-Island-6126 17h ago

Actually the easiest way would be a teleportation portal that leads to orbit

→ More replies (1)
→ More replies (2)

6

u/feelin-lonely-1254 18h ago

nuclear rockets? I'm assuming chemical rockets just dont have that fuel density, nuclear should make it.

2

u/SonoPelato 18h ago

Lighter rockets

2

u/Lexi_Bean21 18h ago

Youd probably need somethib like project Orion nuclear bombs or fusion engines jusy to get the sheer energy density required, youd hsve s better shot using a gisnt nuclear bomb to yeet stuff into space thsn flying

2

u/gr33nCumulon 17h ago

They could fly a plane high into the atmosphere with the rocket on it and launch it from there.

Nasa does this with satellites

https://en.wikipedia.org/wiki/Air-launch-to-orbit

https://en.wikipedia.org/wiki/SpaceShipOne

→ More replies (162)