The tallest people on that planet
I’ve been wondering this for years now. Sci fi and even actual scientific speculation tends to assume aliens would be way ahead of us in terms of technology because their planets may have been formed earlier. I don’t think time alone matters. If they don’t have resources, if fhey don’t evolve the same way, if they have more difficulties in doing shit due to any number of reasons… They could be far less advanced than us. Maybe nobody in the entire universe has figured out how to realistically travel between stars yet. Maybe we are the only ones who have even managed to get off our rock.
Maybe they just don’t want to leave their planet because it’s dope af
Some humans want to travel even when they’re perfectly happy.
I wonder what another being would need of us if it was already able to travel through the vacuum of space while self-sustaining. We’re basically doing that right now anyway.
They’d want our coconuts, I bet. They’re pretty cool, I bet aliens don’t have coconuts. They might have some cool alien fruit to trade for coconuts. Or weed.
alien pointing at a coconut tree
Look, m’lord! Horses!
Imagine all the room for activities! (Trench warfare)
If the planet is massive enough, getting to orbit becomes a real challenge because fuel consumption scales roughly exponentially with the mass of a planet (delta-v formula, rocket equation).
This leads to an almost sharp cut-off for the maximum mass that a planet can have so that a rocket which utilizes chemical fuel (e.g. methane+oxygen) can still reach orbit successfully. This maximum mass is roughly 10^26 kg.
For reference: Earth’s mass is around 6*10^24 kg.
While other propulsion types exist, such as nuclear + ion drive, these propulsion types are significantly more complicated.
Interestingly, if a planet is too small, it cannot hold an atmosphere. There is a surprisingly sharp cut-off minimum mass for this as well, at roughly 10^21 kg.
I did not know that. It’s because it interferes with gravity? I’m dumb sorry
Not enough gravity, the atmosphere will drift away from the planet with the help of solar winds etc. Too much gravity, and the ammount of fuel you need to leave the plannet weighs more than the rocket the fuel is being used to lift can carry.
Even in our current ships, most of the fuel used to leave orbit is really used to carry the other fuel you need later.
We really are in the Goldilocks Zone, aren’t we?
Well, yes. In the middle of the goldilocks zone that is based on the environment we are adapted to is where you would expect to find us :p
Haha fair point.
Only if there are not sentient life forms on that planet capable of getting off it
What if, and hear me out… Giant trebuchet?
If anything, it’d be a bias towards spaceplane designs over straight up rockets. As long as the atmospheric density relative to the gravity supports it, offloading some of the acceleration to high atmospheric flight using ram/scramjets can massively reduce the launch vehicle mass (don’t need to carry oxidisers for the flight stage).
That being said, it also would be a bias against high orbits and space exploration in general; safe re-entry is tricky enough on earth.
I suspect that atmosphere composition makes different options more or less viable.
The difficulty/cost getting to orbit probably also would influence where a space elevator lands in terms of developmental priority.
We make a mistake by assuming that life forms would likely be at the same scale as us. Larger planets would likely develop life forms appropriate for those planets instead of appropriate for ours.
Damn. As if the atmosphere wasn’t enough of a hurdle already, they gots dumpys too
I wonder at what point it is worth building a
space elevatorspace pyramid.Just keep stacking rocks until you’re a few dozen miles away from the edge of space.
yeah this idea actually exists, i think it’s called a mass driver, which is essentially a very high-speed rail gun, that shoots objects directly into orbit without the object having to have much of a propulsion system itself.
This obviously only works if the object isn’t slowed down by atmosphere, which means you’ll have to launch it from high enough up.
This is where the pyramid comes in. You can, of course, also utilize naturally occurring mountains, if your planet has any. These mountains would have to be rather high, though. Like on earth, maybe 100 km. The highest we have are 8 km.
Technically this is just a subtype of Verne gun. Which fun fact kinda existed. Back in the 60s HARP fucked around with a power charge based one down in Baja to achieve sub orbital space flight for a satellite.
Also Sadam Husein wanted to create one so do with that what you will.
Now I’m curious what would actually happen if a planet’s species dedicated themselves to making it happen, build a pyramid up to a geosynchronous orbit so you could theoretically throw something (or jump) and it’ll end up in a higher orbit.
The physics wouldn’t work, of course, but I’m curious exactly how things would go wrong and if there were engineering solutions available to get to the next big thing.
Like one thing is how tall can you get before the base encircles the planet (where trying to add more layers just makes the planet bigger and requires bringing in outside material, which means your geosync orbit gets farther).
Though as you add layers, the surface area increases, so your “pyramid” is actually getting wider as it gets taller, at least at the base.
Or if you can get really high without encircling the planet, how high can you go before affecting the centre of gravity? Could a large enough pyramid give the planet a wobble? Cause flooding on the near side and sea level drops on the far side? How high can you build a solid pyramid before the pressure of it all makes the lowest bricks get melty? Would it even matter or does the rest of the weight just hold it all in place? Or would a sufficiently large pyramid just explode because the sides would give out?
Assuming you had a perfectly strong material that could handle it, is it possible to build a tower to a geosynchronous orbit or will it keep moving away as you add mass to the tower? Would such a tower float in place if you kept building it out past that point and then detached it from the ground?
You definitely wouldn’t want to do this all the way to geosynchronous orbit. Just getting it to the edge of space is already ridiculous to the point where it has me questioning how much pressure and heat the stone at the bottom would reach, and therefore how stable it would be.
And for a super earth, getting out of the soupy atmosphere is a challenge in of itself, so getting rid of that challenge would already be an incredible head start. From there you’d just need engines powerful enough to get you up to speed before hitting the ground.
Like one thing is how tall can you get before the base encircles the planet (where trying to add more layers just makes the planet bigger and requires bringing in outside material, which means your geosync orbit gets farther).
Gut vibe tells me that probably wouldn’t be a problem, as the atmosphere on any given planet, even a super earth, is only about as thin as the skin of an apple relatively speaking. And that’s all you’d need to beat here.
Could a large enough pyramid give the planet a wobble?
Absolutely. Though again gut vibe tells me it would probably only be a wobble of a few millimeters, nowhere near enough for anybody to feel it.
Assuming you had a perfectly strong material that could handle it, is it possible to build a tower to a geosynchronous orbit or will it keep moving away as you add mass to the tower?
I think at a certain point you’d be far enough up that you could reasonably just build a space elevator on top of the pyramid out of normal-ish materials like steel. The farther up you start the less of a foot you have in the gravity well, and the less distance your steel needs to support. At that point it would maybe be worth it do build a counterweight and go to geosynchronous orbit.
Another thing to keep in mind, if some civilization was crazy enough to do this, hopefully they’d be smart enough to do it around their equator to reduce the amount of pyramid of doom they’d need to build. But that would probably also mean bulldozing lots of countries and mass migrations.
To put something in orbit, it has to go sideways very quickly. It has to rotate around earth, such that the free-fall causes the curvature of the circle. For Low Earth Orbit, that’s 7 km/s. You have to get it to that speed, just “jumping” isn’t enough. You’d need some kind of railgun or catapult.
Wouldn’t that much stone alter gravity enough to raise the atmosphere?
It definitely would, but I’m guessing you’d run into the issue of stability far before that.
I’m also guessing that the ratio of atmospheric extension to terrain extension would be on the side of terrain extension. Gravity is a rather weak force in comparison to the other forces of the universe.
This would be a fantastic xkcd “What if?” question if it isn’t already.
You underestimate the motivation of sentient species that just want to get away from other members of its species.
They’ve just got to dig a hole down through the core of the planet and then drop craft down the hole to “slingshot” them into orbit.
I love slingshots that pull from all sides at once.
I’d sling that shot
Or it’s likely a mini-Neptune type planet with more atmosphere than ground and therefore likely won’t have complex life at all. Or complex life able to try and do that.
Imagine a terrestrial planet that is Earthlike in all respects, but it simply has more persistent cloud cover, such that seeing an open cloudless sky is miraculously unlikely, as unlikely as humans directly witnessing an asteroid impact.
No ground based astronomy.
No technological discoveries or culture that derives from ground based astronomy.
No celestial navigation on the ground.
Very different / stunted / more difficult cartography.
Technological civilization is capable of emerging, but it would not be able to well understand anything beyond the terra firma, not untill it generated aircraft capable of breaching the cloud cover layer, and then developed airborne observatories.
This is a Doctor Who Christmas Episode
“Nightfall”, by Arthur C. Clarke is a short story based on this premise.
Except in the story it’s a complex multiple-star solar system that makes it very rare for all suns to set at once.
Edit: It’s actually Isaac Asimov.
Augh!
You’re telling me there’s an Arthur C Clarke short that I missed?
Damnit I am losing so many nerd points today.
points regained, even doubled!
It’s an Isaac Asimov story. An excellent one I cite frequently with regards to human ability to cope with increasing rate of change.
Whoops! That’s my mistake.
thanks for the good read!
I have written a post about exactly this phenomenon, arguing that that’s how most animals/insects see the world (assuming their sense of vision isn’t good enough or they just don’t care to look up). Apparently i was wrong, even insects can see the stars and navigate due to their light (milky way navigation).
Well, the church threw us back about a millenia, so what’s a few centuries.
Is there a particular instance you’re referring to here? Because contrary to popular belief, the church has historically been big on investing in what we now call science.
For instance, although the trial of Galileo is often characterised as “big bad church holds us back because religion is opposed to heliocentrism”, there was actually a lot of legitimate scientific beef against Galileo. Although he ended up being right about heliocentrism, he didn’t really have good evidence to support his claims; He didn’t understand Kepler’s laws of planetary motion, and his telescope produced so many aberrant artifacts that astronomers who use it were reasonable to be dubious of his claims.
If you’d like to learn more, here’s an excellent video by Dr Fatima, an astrophysicist turned science communicator. The philosopher of science, Paul Feyerabend also uses Galileo as a case study in his book Against Method
Because religion contradicts scientific approach to thinking. I personally like the way in which Carl Sagan gets rid of all the “noise” information when investigating how the world works. Religion is a noise
If you’re a fan of Sagan, you might be interested to hear that he considered that “science is not only compatible with spirituality; it is a profound source of spirituality”.
Religion might be noise for you, but for countless people across history, it has been what has helped them to cut through noise. Religion unequivocally does not contradict scientific thinking — what we understand as scientific thinking wouldn’t even exist today if not for religion.
Things don’t have to be a binary of religion vs science. Religion has so often been the driving inspiration for brilliant scientists across the world, for much of recorded history. And in parallel, there have been religious scholars who find spiritual awe and fulfillment in seeing scientific advances.
That definitely doesn’t mean that everything is always great between religion and science — I’m very much not a fan of things like evangelical Christians who claim that dinosaurs weren’t real, or the Taliban who prevent women from being educated. Those are examples of religion being used as a cudgel against science, but if we want to genuinely resist that kind of thing, it’s not productive to instead try to use science to bash religion. Our best resistance is to embrace the fact that science and religion can and do coexist, in many different shapes and forms.
Part of my stance here is pragmatic — I’m a scientist myself, and I am filled with dread when I see how anti-science rhetoric is flourishing nowadays, and I am resentful as hell towards the many religious assholes who are feeding that. However, if I direct my beef towards religion as a whole, then that’s a heckton of people that I’ve given up on trying to convince. I believe that the scientific method should be a tool that everyone has available in their toolbox, even if it’s not something their daily life often requires — it’s a useful perspective to have on hand no matter your background.
However, I’m realistically never going to convince someone to give up their faith in exchange for this tool, especially as I am not religious myself and thus don’t properly understand what purpose religion serves them. I can make a far more compelling case for science if it isn’t framed as something that seeks to displace their faith. And you never know, once someone does have scientific thinking as a tool in their toolbox, and they know how to use it, they might end up relying on it more and more. I personally know many scientists who have experienced this kind of journey. Though giving up on faith entirely isn’t required, as evidenced by the many excellent scientists I have known whose religious faith drives their passion for research — the best biochemistry tutor I ever had was even a reverend.
Science and religion are not incompatible, and there is evidence of that strewn across history and society. To ignore that fact would be to betray the principles of empiricism that the scientific method is built upon.
Pick a religous war. then pick another. Then knock all the rest of the religous wars into your shopping cart. Now consider future religous wars.
We’re talking about science not wars here.
Also wars are one of the Strongest advancer of science, case in point: jet engine
Have you read Hitchhiker’s Guide to the Galaxy?
Yea but they were playing cricket with the Galaxy
Hah, actually no I have not.
-1 nerd point lol
Good news: it’s all public domain. If you want to read it, it is here. Whole series is there, at least the public domain ones. There was a newer one that wasn’t public domain when I last checked, though that was a long time ago and it might be now.
Don’t read it for nerd points. Read it to find out why it’s associated with nerd points.
Uhh, I couldn’t see anywhere that it’s in the public domain. Could you point me to a source for that?
Series? More then one? So long and thanks for all the books!
Don’t want to spoil anything because you really should, but this is very reminiscent of a plot point in one of the books.
This hoopy frood really knows where the towel is.
Damn, only now did I realize I’ve only read one book in a series
If you want to read the others, check my comment history for a link (it’s public domain).
I wrote and tried publishing a short story about a species like that.
where only occasionally people on top of mountains see stars, and they chuck it as a consequence of low pressure. eventually they invented flight, and assume pilots going high enough to see stars are having cognitive issues due to lack of air.
They asked pilots to draw the stars they see, and they get different drawings (they sent pilots at different times of the year because they couldn’t ever expect stars to shift) and assume its proof that thise stars are a cognitive artifact.
Eventually a pilot swears they are real and can actually use then to navigate, skepticism, he proves it. brand new research field emerges.
Although the story focuses more on deep DEEP time an omniengineering. (A term I just made up because mega engineering is a concept way too small compared to the one in the story).
If you want I don’t mind putting that story in the conversation.
Post it for sure
https://docs.google.com/document/d/1PTzQQKXLnBL1ICUK8IYa8YoUSD2ncQk5-jse-FaFPAI/edit?usp=drivesdk
tried putting the text in a comment, but it’s too long, I enabled comments.
I loved it. Thanks for sharing!
Given who you are, it means a lot.
I liked it. It seems to fall apart at the end a bit but this is a really cool concept for sure.
if you don’t mind. could you elaborate? it’s ok if you don’t, I am rudely asking for free labor.
Seems like you were going for a bit of a twist ending where the letter is actually a threat. It didn’t really land for me.
The threat could be more concise and pointed which would give it more impact. Instead of speculating about how humans may react and then saying the aliens will counter it, maybe just say something that amounts to “resistance is futile”.
Its also not exactly clear to me what “the problem” is. Its that their race will someday come to an end? There is a lot to be said about this idea and I think you should explore the philosophy of that more. How does prolonging their existence save them? Seems to me like they’re still left with the inevitable.
the problem is the inevitability of the heat death of the universe, and the meaningless of existence if there’s no life at the end.
While the solution is to optimize the entire universe, though massive galactic engineering (using plausible physics) to maximize their research in order to break thermodynamics. I’ll try to make it clearer.
the ending is clear, but wether it’s good or bad is ambiguous and up to the reader, as they basically incarcerated humanity on earth and took away any possibility of humanity ever leaving earth. without any negative effects on the planet or humans.
That was a good read! I liked the pacing, the dawning not quite horror.
Shit yeah go for it, I love those kinds of stories!
https://docs.google.com/document/d/1PTzQQKXLnBL1ICUK8IYa8YoUSD2ncQk5-jse-FaFPAI/edit?usp=drivesdk
tried putting the text in a comment, but it’s too long, I enabled comments.
thank u, good read
I’d read it
https://docs.google.com/document/d/1PTzQQKXLnBL1ICUK8IYa8YoUSD2ncQk5-jse-FaFPAI/edit?usp=drivesdk
tried putting the text in a comment, but it’s too long, I enabled comments.
Heck yeah, I’d read that. Feels like it could have been a Hal Clement story idea.
https://docs.google.com/document/d/1PTzQQKXLnBL1ICUK8IYa8YoUSD2ncQk5-jse-FaFPAI/edit?usp=drivesdk
tried putting the text in a comment, but it’s too long, I enabled comments.
Thanks! Will review.
no pressure. and be honest, if some parts are shite tell me. and especially if it is all shite.
Well, as soon as they invent radio and experience interferens radio astronomi will evolve… I guess?
Project Hail Mary has a bit about this, don’t want to say more to keep it spoiler free.
Haven’t seen it yet, I appreciate the nonspoiling =D
iirc that detail they are refering to, didnt make it into the movie.
Yes, correct, they skipped a lot of the harder science for the movie to keep it a reasonable length. Movie was still very good though!
Definitely read the book. The book is about the existential elation at discovering a solution to a dire problem, so knowing a poorly-communicated version of every solution will likely ruin the book for anyone serious about the hard Sci-Fi.
I would instantly buy your book!
Hah, I haven’t written one, but maybe check out Arthur’s short story elsewhere in the comments!
He’s got uh… watermelon emojis in his name.
That just sounds like a hollow world…
To everyone saying launching to orbit is impossible, I have two words: Orion Drive
Early versions of the vehicle were designed for ground launch, but later versions were intended for use only in space.
I don’t think a ground launch Orion Drive would work without some crazy material science and infrastructure. Like a “flame trench” that can withstand a nuclear blast and a craft that doesn’t rip itself to shred just from the shockwave alone.
Technically you only need a launch tower designed in such a way that none of its shrapnel damages the rocket.
And we have the materials science for the plate.
so it’s possible, once
Jokes on us: Because of the gravity issue, alien life on such planets jumps right to stargate technology.
“They spent almost a thousand years fooling around with rockets!”
Waddayamean a « ro-ket »? You guyas don’t use the three seashell system for liftoff?
Uhh, one stargate doesn’t go anywhere.
that’s why you communicate via radio waves to other life in the area and build a network
You can accelerate it into space at g forces which would liquify living beings, perhaps?
Using what?
(Remember the premise of this subthread is that they’re doing this instead of rockets.)
Bah, Stargates are just propaganda from the rocket first civs.
There is no need to send a gate in advance, just use your favorite teleportation mechanic.
I’d say they stand a whelks chance in a supernova of that succeeding.
Actually I’m a marine astrobiologist and that chance is really really high
Just frisbee those things in random directions until one works.
According to Wikipedia this planet has an estimated surface gravity of 12.43 m/s^2 with a margin of error of about 2 m/s^2. That’s only up to 50% higher than Earth’s 9.8 m/s^2 (on the high end of the error margin) so it probably would be possible to get into orbit.
That said we don’t actually know much about it for sure. We don’t know if it’s a terrestrial planet for example. It could be composed mostly of gases and liquids like Neptune.
(Not a rocket scientist or mathematician, but I spent 100s of hours playing KSP RP-1)
Just doing some estimates using data from the wikipedia page:
The dV (delta-V) needed to get into low Earth orbit is around 9.4km/s.
The dV for K2-18b might be around 19km/s, more than double that of Earth’s.It’s practically impossible I think, you would need such a massive launch vehicle. For double the dV, you would need exponentially more fuel assuming current rocketry tech (fuel+oxidizer tanks and engines). There wouldn’t be any single-stage or two-stage rockets that could do this. With a 3 or 4 stage rocket maybe? But you would be sending nearly 100% fuel off the launchpad with virtually zero payload.
Check out the “tyranny of the rocket equation”. The more propellant you need to lift heavier rockets, the more propellant you need to lift that extra propellant and so on and so on.
I tried to factor in:
spoiler
- Atmospheric drag - K2-18b’s atmosphere is quite dense with a huge radius:
The density of K2-18b is about 2.67+0.52/−0.47 g/cm3—intermediate between that of Earth and Neptune—implying that the planet has a hydrogen-rich envelope. […] Atmosphere makes up at most 6.2% of the planet’s mass
-
Since the atmosphere is so thick and takes up a lot of mass, I’ve picked 500km as the low orbit altitude (comparing to Earth’s ~100km Karman line, it makes you appreciate how thin our atmosphere is ).
-
Rotational assist - I’m assuming it’s tidally locked since it orbits so closely to its star (33 day years), and so you wouldn’t get the assist from rotation like you do on Earth:
The planet is most likely tidally locked to the star, although considering its orbital eccentricity, a spin-orbit resonance like Mercury is also possible.
You don’t have to launch from the ground, there are many things that can be done to allow them to reach orbit. It’ll be an enormously bigger undertaking but the physics doesn’t make it impossible. No reason to think of it in terms of our current situation either, and we are behind our current level of possibly when it comes to rocket science, due to * waves at everything else *
Kerbal Space Program is such an amazing game that secretly teaches you physics.
game that secretly teaches you physics.
those are the best!
With a denser atmosphere, wouldn’t that mean that you could get more lift from a traditional aerofoil than on earth? And if so, wouldn’t that technically make it easier to start from a high enough altitude that at least some of the gravity is mitigated?
Let’s say you do the same on Earth. If you fly to the top of the atmosphere you are 100 km above the ground. That’s a 1/60 of the distance to the center of the Earth. You don’t have to fight air resistance but gravity is almost the same, if I’m not wrong, less than 1% of difference.
Yeah I realized that right after I made that comment. If the gravity is strong enough to hold a gas on the planet, it’ll definitely have a prominent effect on something denser like a solid.
That’s what i was thinking - the dense atmosphere might even allow for platforms which are permanently suspended in the air like an inverse submarine, offsetting a large amount of needed fuel for a space launch
What about something like nuclear pulse propulsion, or some kind of massive spin launch?
Nuclear propulsion, like Project Orion, would probably make it more likely they’d manage to get out of orbit. No idea on the math here, tho
https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion)
yeah there’s also antimatter drives which give an even greater effective exhaust velocity (which is the speed of light). the highest possible achievable.
none have been built, so far
If it’s tidally locked, no spin assist.
Likely tidally locked
Missed that part but that doesn’t preclude what I was saying, just requires “more” of it
Check out the “tyranny of the rocket equation”.
Or ask Randall Munroe How many model rocket engines would it take to launch a real rocket into space?
tidally locked
Wouldn’t that be a non starter for life? One side would be perpetually baked and the other would be frozen.
I guess there could be a planetary Goldilocks Zone in the dusk area
I figured that area would be full of extremely violent megastorms due to the heat differential.
Oh interesting that is a good point
Build a large enough magnetic rail launcher and you could save shit tons of fuel. Get a ship doing 2000 mph before it leaves the ground and needs its rockets and you’ll have a pretty good head start.
Could even take a scramjet to the upper layers of the atmosphere before kicking in the chemical propulsion
It’s probably still a lot harder though. You’re not just heavier, but also slower which means you’ll spend more time fighting gravity. And all the extra fuel you bring for that makes the rocket heavier which means you need even more fuel to launch the fuel. Higher surface gravity likely means a thicker atmosphere too which is a big issue and a more massive body also has a faster orbital velocity. Although in this case the larger diameter might counteract that a bit because higher orbits have slower velocities.
My point is that this would probably still be a lot harder than just building a 50% bigger rocket. If you’ve ever tried launching from Eve in Kerbal Space Program you know the pain. Although in that case you also have to fly the entire rocket there first which is its own challenge.
you’ll spend more time fighting gravity
Aw man. This is already a significant portion of my day.
It would actually be impossible for them to get to orbit using chemical rocketry, like we use. They could theoretically do it with nukes.
I’ve been wondering what a hypothetical perfect habitable planet for spacefaring would look like. Could you have one where a plane line the SR-71 Blackbird or an even less capable aircraft could simply “fly” into orbit? Or what about something Earth-like but with a flat plateau at 15,000 m where you could launch rockets from?
Mars is better for launching rockets into deep space than Earth because it has a lower gravity field and also thinner atmosphere.
I think Mars, assuming you terraform it, would be pretty close to that on both counts. Space planes might still be difficult, but the delta V is much lower and Olympus Mons would pretty much sit above the atmosphere.
Holy shit, I hadn’t considered that you could use Olympus Mons as a launch site cause it sticks so high up.
The best part about it is that it’s an extremely gradual slope completely unlike the mountain ranges on Earth, so you could haul stuff up there on trucks or trains easily.
The problem is you can’t have mountains like that on tectonically active planets (a mountain that big on earth would sink into the mantle), which is kind of a prequisite for a long-term magnetosphere so its unfortunately not something a species could likely ever have except as a result of terraforming a world like mars and setting up some kind of artificial magnetosphere.
If that’s true, how did Olympus mons get there in the first place? I thought it was a volcano.
Mars was geologically active but its core cooled.
Is there a lower density limit for having a magnetosphere though? A habitable planet with 1.5x earth radius and the same mass would be much easier to get off of.
I guess that could work? Earth is actually the densest planet in the solar system so our baseline mass > size ratio might actually be a bit abnormal.
Classic planes require an atmosphere to generate lift. There’s an outer limit where that would be a viable mechanism, and on Earth it’s still far below LEO. Still too deep in the gravity well for ion thrusters to be viable. It requires chemical rocket fuels to bridge that gap.
Maybe someday fusion propulsion will break that limitations, but for now the best you can do is reduce the amount of fuel needed by flying to the upper atmosphere and reaching hypersonic speeds before kicking into rocket fuel propulsion.
Then after orbital injection, switching to ion thrusters to move around, and solar sails for exiting orbit into interplanetary/lunar routes.
Orbital speeds would be very hard to reach compared to low Earth orbits. Also a much deeper gravity well to escape for travel.
I assume it’s not just about the gravity, but also the much larger radius of the planet would mean much larger distance from the surface, and thus much more fuel needed.
That’s not how…what???
F = G * (m1 * m2) / r^2
Note that radius is both squared and the dividing term. More distance = less gravity
Escape velocity does scale with (square root of) radius so its not a dumb thought.
And I’m not a rocket surgeon but I could imagine earth rockets might be operating near some physical limits that make a 50% increase (or whatever) infeasible.
Wikipedia says
energy = GMm/r.if
g=GM/r²thenenergy = mgr, proportional to r given g is constant.apologies
My previous comment was wrong, I derivated while integrating.
I stated an assumption and was contributing to the conversation. Even if that assumption is incorrect, there’s no need to be a dick about it.
It seems like a larger atmosphere would result in a longer duration exposed to atmospheric drag, thus requiring more fuel to overcome it.
deleted by creator
That’s, uh, not really how that works. A taller atmosphere would mean you have to go through more of it, but unless it’s not a terrestrial then the atmosphere won’t be that much taller.
If it is a non-terrestrial planet, it’s unlikely anyone would be building rockets on there to begin with.
If it has a higher gravity would the atmosphere technically be lower since it will squish up closer to the planet?
And your username would also be relevant.
You’re sort of right. The change in distance from the surface is insignificant, but a spacecraft orbiting a bigger planet has to travel further with each orbit so its speed must be faster to avoid falling out of orbit, even if the gravitational acceleration at its orbital height is the same.
Or Uranus.
Or your mother’s.
The interesting thing about this is that it could be a double whammy. The collision that formed the Moon not only made Earth smaller, it also ejected a lot of material away from the orbit. This made Earth even smaller than it would otherwise have been, had the two bodies merged. And the Moon also formed in the process. The Moon causes the tides which are theorized to have a significant beneficial effect on evolving more complex forms of life.
So just being small might not be enough and having a big moon might also not be enough, but Earth was lucky enough to have both. And that’s just some of the things in a long list of things that have to go right to get complex life on a planet.
My feeling is that life is pretty rare, but given there are so many star systems in our galaxy there might be a lot of it still. But most of it is probably very simple stuff. Getting to where Earth is, might be a once every couple of millions of years event within our entire galaxy. So there really might be nothing intelligent out there at this moment in time, there might have been earlier and there might be in the future, but for right now we are it.
Fun fact worth noting: humans and octopodes split back when our shared bodyplan was effectively a worm who just got legs. Octopuses have been shown to be able to learn and memorize letters, patterns, their different keepers (e.g., spitting at one particular keeper they didn’t like), etc., and all the intelligence they’ve been demonstrated to learn evolved separately from humans.
So we’ve actually got two examples of “worm with newly-evolved legs” becoming pretty damn smart on Earth, not just one - which makes my bet more on the “if the biosphere got to worms with legs, there’s a lot of smart stuff there”
I hear a biologist once say that if the octopus could live to be 80 like humans, they would be in charge of the planet instead of humans.
Wow I had to look up their lifespan because I thought they were theoretically immortal (it was a jellyfish i was thinking of). Only 5 years and octopus can be this smart? The psychotic hairless apes got off easy this time.
Yup, I wonder sometimes, all those sci-fi tales about a long lost ancient civilisation that spread throughout the galaxy before everyone else did, what if we’re set to become that, before space-faring life eventually emerges, then thrives and flourishes all over the galaxy?
One can dream anyway…
Try Revelation Space by Alastair Reynolds, the whole series is great.
Oh, thanks, will do!!
What gets me are the people that insist that humans can’t be exceptional and be the first civilization in the galaxy because we’re really dumb… which is it’s own exceptionalism.
If you really thing humans are ‘meh’, the solution to the Fermi Paradox that fits best is that we’re lucky and among the first civilizations. Especially when you consider that the universe hasn’t been hospitable to life until very recently
And that’s just some of the things in a long list of things that have to go right to get complex life on a planet.
There’s ground bacteria that adapted to live in human-made tar lakes, digesting tar instead of straw.
I assume the amount of energy required for ‘only’ 50% more is massive.
Apparently with 50% higher gravity it would be pretty much impossible with chemical rockets, but with the median of the estimate (so about 12.43 m/s2) it would be possible, you’d just need an incredibly large rocket, or non-chemical propulsion (e.g. nuclear).
A space program on that planet would definitely advance much slower than on Earth.
How well funded have our space programs been? Maybe they aren’t diverting massive portions of their resources to war and can actually focus on space.
They were well funded back when their real goal was to develop ICBMs capable of delivering nukes.
I get what you are saying, but the Saturn V was never intended to be an ICBM. Depending on what numbers you look at too, they weren’t actually that well funded. Some of the largest estimates that I’ve seen place NASA’s inflation adjusted budget between 1960 and 1973 at just under $600 billion. Or roughly half of what we’re spending in one year on the military currently.
To put it another way, at its absolute peak budget NASA received roughly 4.6% of the current military budget.
Iirc near that +50% level you end up needing a saturn 5 to launch sputnik, so its more expensive to the degree that it might just be deamed unfeasable, at least at the technology level humans started launching rockets at.
Much slower as in hundreds or thousands of years, so practically no difference at all.
Also i wonder since the diameter is larger, is this effectively like putting everything in a higher orbit which is also more difficult then if it was just twice as dense.
That really depends on the atmosphere. The lower the orbit the easier, but if you have too much drag from the atmosphere, you ain’t staying on that orbit easily
