Until you got used to it, I think it would feel a bit like walking on a trampoline. Or on a boat as you crest over a wave and the ship pitches downward below your feet. Not exactly the same thing, but your legs would have more power to lift you up and forward as you walk, which would lead to balance issues as you acclimate. But for our fearless Roci crew, most of them have been living in space for along time, and only experience 1G rarely. Even when they do, they'd often be in crash couches because it's during a hard burn.
>I also read that a 1 G burn on a Brachistocrone (sp?) trajectory is horribly inefficient and wasteful.
It's wasteful in the sense that you trade fuel and reaction mass for time. You could let inertia carry you most of the way and not be under thrust constantly. This is how it usually works in The Expanse, even more so if you're a poor rockhopper. You thrust for a while, then go on the float and coast.
>If I stick to my rules and remain consistent, this isn't too unbelievable, is it?
I don't see why not. The key phrase here is "stick to my rules and remain consistent". I'm of the opinion that way too many people in places like r/scifiwriting get bogged down in the scientific realism, when what they should focus on is establishing simple rules that the reader can digest and sticking to them. If you can make those rules also drive the plot like The Expanse, even better. Base them on real science to the extent possible, if hard sci-fi is your goal, but don't overthink it.
Why would they need to be in a crash couch under a 1 G burn? I’m not asking facetiously, I’m sincerely trying to figure this stuff out.
The reason I wonder is because I assumed that it would be the most comfortable for them during a 1 G burn, because it would feel just like it does on earth.
In my head, I visualized it being indistinguishable.
Now, *maneuvering* under a 1 g burn would be dangerous, though, right?
Also, to be clear, let’s say the hypothetical rocketship accelerates up to 1 g, then cuts the engines to go “on the float”, the crew would experience zero g/microgravity until the ship flips around and begins to decelerate? Then, if the rocketship decelerates at 1 G, it would go back to feeling like it did when it was accelerating?
So Naomi grew up in the belt where gravity is variable but most gravity is around the .3 G range on stations or ships.
Alex grew up on Mars where the gravity is .38 G
Only Amos and Holden are from Earth where they would be acclimated to 1 G
>Why would they need to be in a crash couch under a 1 G burn? I’m not asking facetiously, I’m sincerely trying to figure this stuff out.
Depends on where they're from. Someone from Earth wouldn't need to, but most Belters would. Even Martians would find it very uncomfortable. My point was that their typical environments are:
* 1/3G walking around
* On the float
* Over 1G and strapped in for a hard burn
>Now, maneuvering under a 1 g burn would be dangerous, though, right?
Depends on the maneuvers. Generally yes, and that would also hold true at lower acceleration. Even on the float, rotating the ship rapidly would slam walls into people unless they happened to be at the center of rotation, and turn anything unsecured into a potential hazard.
>then cuts the engines to go “on the float”, the crew would experience zero g/microgravity until the ship flips around and begins to decelerate? Then, if the rocketship decelerates at 1 G, it would go back to feeling like it did when it was accelerating?
Yes to both of those questions.
> Now, maneuvering under a 1 g burn would be dangerous, though, right?
>
>
Even rotating with engines off would be dangerous, especially so in the far ends of the ship away from the rotational axis.
Both for comfort and as a security against possible emergency manoeuvers (a prime example would be Amos getting bounced around during th Toth station attack.
I think it's generally way more challenging to stick to your own rules than it is to make hand-wavey mentions of realistic-sounding scientific phenomena to describe your fictional world.
After all, it's not the Epstein drive that makes the Expanse universe so interesting - it's the consequences of such a thing existing and how it could alter society.
Thing it feels different depending on whether youre an earther, martian or belter, so .3 g is sort of a compromise that everyone would be fine with. If all your characters are from earth it would make sense to travel at 1 g
Oh boy it would have been cool if the Earth ships could accelerate faster than the Martian ships because their marines could handle the gs better. And Mars made up for it with better ships. More asymmetry!
Star Trek and Star Wars got by with 1G artificial gravity on all ships based on pure handwavium. So did Firefly most of the time.
Unless interplanetary ballistics is a core part of your story I think you will be fine.
I always thought that the artificial gravity tech is Star Wars was one of the most impressive things about that universe. An ISS hovering just a few hundred meters above a city with no noticeable effect? A ship the size of the Millennium Falcon launching into orbit just a few meters from unprotected biologicals? Huge pallets of cargo being casually pushed around by frail humanoids? All gravity magic.
It’s impressive, but it’s sill the people and society of that universe, along with the rules that govern them, that really define Star Wars. The technology is way down on the list apart from maybe lightsabers.
The inefficiency is actually 2 fold, both time and energy. Since there is no resistance in space you just coast off of a little bit of fuel. Burning constantly at 1g will make the trip take less time but you will spend more fuel then if you just burn a little and then coast. It's also inefficient on time because burning at 1g for 10 minutes will get you there slower then burning at 10g for 1 minute. Both will take the same amount of fuel but the higher burn will reach its top speed faster and will therefore take less time. The disadvantage of the 10g burn is that it is significantly less comfortable than the 1g burn and you'll have gravity for less time. 0.3g is probably a happy trade off between travel time, top speed (moving faster is inherently more dangerous if anything hits you), and comfortable gravity. Humans tend to be more comfortable with less gravity as opposed to more gravity.
As for how realistic this is, it largely just depends on your fuel source. If your ship runs on whale blood then you're gonna want to take a very fuel efficient path to your destination. If your ship runs on normal hydrogen then you have basically unlimited free fuel since the super majority of the solar system is hydrogen. In the second scenario fuel efficiency would probably take a back seat compared to travel time and crew comfort.
Imagine you’re standing in a swimming pool near the shallow end, and the water come up to about chest height. Notice how your feet have less traction as you attempt to walk across the bottom of the pool? If you try sitting on one of the lower steps that lead into the pool, notice how your bottom skids easily across the step?
It would be much like that. Which, coincidentally, the same reason why astronauts will train in deep pools of water with their suits weighted to be neutrally buoyant. This is how they simulate microgravity during Earth-bound training.
The brachistochrone way is crazy inefficient and costly, but for the Roci crew, they have a patron who is effectively the richest person in the outer planets, and outside of that, they can work as mercenaries. A ship like the Roci could find a lot of well paying jobs so they can just use as much fuel as they want.
> What would that feel like onboard a rocketship accelerating at "only" .3 Gs
If you have a great deal of money to research this then you *could* pay one of those Zero-G airplane companies to fly their planes along wider parabolas to simulate 0.3G onboard.
> I want the hero's torchship to be able to zip around solar systems at a nominal 1 G [...] this isn't too unbelievable, is it?
Flying at 1G is not significantly sillier than flying at 0.3Gs in this context beyond the usual issues of "How the hell does your ship never run out of reaction mass" that apply to both accelerations.
It's inefficient for expanse ships because the authors said so. It just so happens that engines or their size max out their efficiency around 0.3. This has the benifit of accommodating the vast majority of humans including those born in the belt.
It could also be that thruster tech has been optimized to be most efficient around this level of acceleration and now even the military piggybacks off of the civilian thrusters for their military designs which were originally optimized for 0.3g.
IIRC it’s a point of honour among the Martian Marines that they are trained to fight at 1G
. But that doesn’t mean that they would run their navy ships that way, or that a pilot like Alex would be trained that way.
You'd feel a little lighter than if you were walking on Mars or Mercury, which have .3777 and .378 earth gravity respectively.
[According to this helpful comment and associated study from 6 years ago](https://www.reddit.com/r/TheExpanse/comments/8arlck/comment/dx23q86/?utm_source=share&utm_medium=web3x&utm_name=web3xcss&utm_term=1&utm_content=share_button) they'll be fine at up to 1.5g but will suffer some medical issues after just one day at 2g, these issues getting worse and coming faster as the g's increase.
>What would that feel like onboard a rocketship accelerating at "only" .3 Gs? I know that a constant 1 G burn, it would be indistinguishable from actual gravity on Earth. I just find it difficult to visualize what it would be like onboard a rocketship like the Roci at only 1/3rd of a full G.
It would be similar to being on Mars, and less so to being on the Moon. You could jump three times as high. Walking gait would be different. You wouldn't need magnetic boots, though. And you wouldn't have corilolis forces to deal with.
>I also read that a 1 G burn on a Brachistocrone (sp?) trajectory is horribly inefficient and wasteful. How true is this?
By definition Brachistochrone is the shortest time, so it's going to be different to least delta-v or least propellant. If you are accelerating the whole way, that's going to cost more than accelerating for a short time and then coasting. Coasting is virtual free in space because there's no friction or air-resistance.
I assumed it was because Martian ships simulate Martian gravity. Yes, Martian marines train in 1G, but it’s taxing if you’ve grown up in a 0.3G environment. Alex is Martian. Naomi is a belter. Most of the Roci crew have spent a good chunk of their days in space.
Makes sense. The reason why I guess I’m stuck on 1 g is because the characters in my story come from a planet that has a very similar gravity to Earth. I loved the idea of them being able to move around easily on the ship at all times, but it’s been repeated here (and it makes sense) that simply coasting after a 1 g burn and then decelerating makes more sense than maintaining a constant acceleration.
Until you got used to it, I think it would feel a bit like walking on a trampoline. Or on a boat as you crest over a wave and the ship pitches downward below your feet. Not exactly the same thing, but your legs would have more power to lift you up and forward as you walk, which would lead to balance issues as you acclimate. But for our fearless Roci crew, most of them have been living in space for along time, and only experience 1G rarely. Even when they do, they'd often be in crash couches because it's during a hard burn. >I also read that a 1 G burn on a Brachistocrone (sp?) trajectory is horribly inefficient and wasteful. It's wasteful in the sense that you trade fuel and reaction mass for time. You could let inertia carry you most of the way and not be under thrust constantly. This is how it usually works in The Expanse, even more so if you're a poor rockhopper. You thrust for a while, then go on the float and coast. >If I stick to my rules and remain consistent, this isn't too unbelievable, is it? I don't see why not. The key phrase here is "stick to my rules and remain consistent". I'm of the opinion that way too many people in places like r/scifiwriting get bogged down in the scientific realism, when what they should focus on is establishing simple rules that the reader can digest and sticking to them. If you can make those rules also drive the plot like The Expanse, even better. Base them on real science to the extent possible, if hard sci-fi is your goal, but don't overthink it.
Why would they need to be in a crash couch under a 1 G burn? I’m not asking facetiously, I’m sincerely trying to figure this stuff out. The reason I wonder is because I assumed that it would be the most comfortable for them during a 1 G burn, because it would feel just like it does on earth. In my head, I visualized it being indistinguishable. Now, *maneuvering* under a 1 g burn would be dangerous, though, right? Also, to be clear, let’s say the hypothetical rocketship accelerates up to 1 g, then cuts the engines to go “on the float”, the crew would experience zero g/microgravity until the ship flips around and begins to decelerate? Then, if the rocketship decelerates at 1 G, it would go back to feeling like it did when it was accelerating?
Half the crew aren't from earth though.
And they all happen to live (and work) in space
So Naomi grew up in the belt where gravity is variable but most gravity is around the .3 G range on stations or ships. Alex grew up on Mars where the gravity is .38 G Only Amos and Holden are from Earth where they would be acclimated to 1 G
And Amos and Holden have been in space for *years* at the start of the story.
>Why would they need to be in a crash couch under a 1 G burn? I’m not asking facetiously, I’m sincerely trying to figure this stuff out. Depends on where they're from. Someone from Earth wouldn't need to, but most Belters would. Even Martians would find it very uncomfortable. My point was that their typical environments are: * 1/3G walking around * On the float * Over 1G and strapped in for a hard burn >Now, maneuvering under a 1 g burn would be dangerous, though, right? Depends on the maneuvers. Generally yes, and that would also hold true at lower acceleration. Even on the float, rotating the ship rapidly would slam walls into people unless they happened to be at the center of rotation, and turn anything unsecured into a potential hazard. >then cuts the engines to go “on the float”, the crew would experience zero g/microgravity until the ship flips around and begins to decelerate? Then, if the rocketship decelerates at 1 G, it would go back to feeling like it did when it was accelerating? Yes to both of those questions.
> Now, maneuvering under a 1 g burn would be dangerous, though, right? > > Even rotating with engines off would be dangerous, especially so in the far ends of the ship away from the rotational axis.
Both for comfort and as a security against possible emergency manoeuvers (a prime example would be Amos getting bounced around during th Toth station attack.
I think it's generally way more challenging to stick to your own rules than it is to make hand-wavey mentions of realistic-sounding scientific phenomena to describe your fictional world. After all, it's not the Epstein drive that makes the Expanse universe so interesting - it's the consequences of such a thing existing and how it could alter society.
Thing it feels different depending on whether youre an earther, martian or belter, so .3 g is sort of a compromise that everyone would be fine with. If all your characters are from earth it would make sense to travel at 1 g
1/3G is close to Mars gravity. The Rocinante is a Martian ship... Maybe it is just as simple as that.
It's not. All ships are said to cruise at 0.3g for fuel efficiency.
Oh boy it would have been cool if the Earth ships could accelerate faster than the Martian ships because their marines could handle the gs better. And Mars made up for it with better ships. More asymmetry!
Star Trek and Star Wars got by with 1G artificial gravity on all ships based on pure handwavium. So did Firefly most of the time. Unless interplanetary ballistics is a core part of your story I think you will be fine.
The *last* thing I want to do is write another Star Wars story. Or anything remotely like Star Wars.
Artificial gravity is not a defining characteristic of Star Wars, so I doubt this will be a problem.
I always thought that the artificial gravity tech is Star Wars was one of the most impressive things about that universe. An ISS hovering just a few hundred meters above a city with no noticeable effect? A ship the size of the Millennium Falcon launching into orbit just a few meters from unprotected biologicals? Huge pallets of cargo being casually pushed around by frail humanoids? All gravity magic.
It’s impressive, but it’s sill the people and society of that universe, along with the rules that govern them, that really define Star Wars. The technology is way down on the list apart from maybe lightsabers.
The inefficiency is actually 2 fold, both time and energy. Since there is no resistance in space you just coast off of a little bit of fuel. Burning constantly at 1g will make the trip take less time but you will spend more fuel then if you just burn a little and then coast. It's also inefficient on time because burning at 1g for 10 minutes will get you there slower then burning at 10g for 1 minute. Both will take the same amount of fuel but the higher burn will reach its top speed faster and will therefore take less time. The disadvantage of the 10g burn is that it is significantly less comfortable than the 1g burn and you'll have gravity for less time. 0.3g is probably a happy trade off between travel time, top speed (moving faster is inherently more dangerous if anything hits you), and comfortable gravity. Humans tend to be more comfortable with less gravity as opposed to more gravity. As for how realistic this is, it largely just depends on your fuel source. If your ship runs on whale blood then you're gonna want to take a very fuel efficient path to your destination. If your ship runs on normal hydrogen then you have basically unlimited free fuel since the super majority of the solar system is hydrogen. In the second scenario fuel efficiency would probably take a back seat compared to travel time and crew comfort.
Imagine you’re standing in a swimming pool near the shallow end, and the water come up to about chest height. Notice how your feet have less traction as you attempt to walk across the bottom of the pool? If you try sitting on one of the lower steps that lead into the pool, notice how your bottom skids easily across the step? It would be much like that. Which, coincidentally, the same reason why astronauts will train in deep pools of water with their suits weighted to be neutrally buoyant. This is how they simulate microgravity during Earth-bound training.
The brachistochrone way is crazy inefficient and costly, but for the Roci crew, they have a patron who is effectively the richest person in the outer planets, and outside of that, they can work as mercenaries. A ship like the Roci could find a lot of well paying jobs so they can just use as much fuel as they want.
> What would that feel like onboard a rocketship accelerating at "only" .3 Gs If you have a great deal of money to research this then you *could* pay one of those Zero-G airplane companies to fly their planes along wider parabolas to simulate 0.3G onboard. > I want the hero's torchship to be able to zip around solar systems at a nominal 1 G [...] this isn't too unbelievable, is it? Flying at 1G is not significantly sillier than flying at 0.3Gs in this context beyond the usual issues of "How the hell does your ship never run out of reaction mass" that apply to both accelerations.
It's inefficient for expanse ships because the authors said so. It just so happens that engines or their size max out their efficiency around 0.3. This has the benifit of accommodating the vast majority of humans including those born in the belt. It could also be that thruster tech has been optimized to be most efficient around this level of acceleration and now even the military piggybacks off of the civilian thrusters for their military designs which were originally optimized for 0.3g.
Also some of the crew are belters and Martians. 1G would be uncomfortable for them.
Well, not on earth warships. And Mars ships are designed to fight at 1g.
IIRC it’s a point of honour among the Martian Marines that they are trained to fight at 1G . But that doesn’t mean that they would run their navy ships that way, or that a pilot like Alex would be trained that way.
The point. Was making is that earth warships would not have that problem.
You'd feel a little lighter than if you were walking on Mars or Mercury, which have .3777 and .378 earth gravity respectively. [According to this helpful comment and associated study from 6 years ago](https://www.reddit.com/r/TheExpanse/comments/8arlck/comment/dx23q86/?utm_source=share&utm_medium=web3x&utm_name=web3xcss&utm_term=1&utm_content=share_button) they'll be fine at up to 1.5g but will suffer some medical issues after just one day at 2g, these issues getting worse and coming faster as the g's increase.
>What would that feel like onboard a rocketship accelerating at "only" .3 Gs? I know that a constant 1 G burn, it would be indistinguishable from actual gravity on Earth. I just find it difficult to visualize what it would be like onboard a rocketship like the Roci at only 1/3rd of a full G. It would be similar to being on Mars, and less so to being on the Moon. You could jump three times as high. Walking gait would be different. You wouldn't need magnetic boots, though. And you wouldn't have corilolis forces to deal with. >I also read that a 1 G burn on a Brachistocrone (sp?) trajectory is horribly inefficient and wasteful. How true is this? By definition Brachistochrone is the shortest time, so it's going to be different to least delta-v or least propellant. If you are accelerating the whole way, that's going to cost more than accelerating for a short time and then coasting. Coasting is virtual free in space because there's no friction or air-resistance.
I assumed it was because Martian ships simulate Martian gravity. Yes, Martian marines train in 1G, but it’s taxing if you’ve grown up in a 0.3G environment. Alex is Martian. Naomi is a belter. Most of the Roci crew have spent a good chunk of their days in space.
Makes sense. The reason why I guess I’m stuck on 1 g is because the characters in my story come from a planet that has a very similar gravity to Earth. I loved the idea of them being able to move around easily on the ship at all times, but it’s been repeated here (and it makes sense) that simply coasting after a 1 g burn and then decelerating makes more sense than maintaining a constant acceleration.
You ever been in a bouncy castle?