19 ms·

Emergency braking in space

57 points by sklargh 4y ago

amelius 4y ago
> Can humans withstand 4 g non-stop for 9 days? They might if you keep rotating them, so the force is not along one axis all the time.
- jermaustin1 4y ago
  Seems like that would cause terrible motion sickness. Rotating would cause centripetal force, so another vector of acceleration on your body PLUS a constantly changing vector of acceleration due to deceleration.
  - tantalor 4y ago
    I imagine amelius intended a regular "flip" like a hospitalized patient to avoid bedsores, not constant rotation.
    - dTal 4y ago
      Immersed in liquid would be the way. Internal organs would still have to bear the load, but your skeleton and musculature could be spared.
EddieDante 4y ago
The phrase "raspberry jam delta-v" comes to mind. Also, the obligatory clip from Spaceballs... https://www.youtube.com/watch?v=NAWL8ejf2nM https://www.youtube.com/watch?v=NAWL8ejf2nM
- xeromal 4y ago
  This specific moment where he still makes the noise after having the microphone smacked from him makes me laugh the same as it did when I was a tiny kid. https://youtu.be/rGvblGCD7qM?t=95 https://youtu.be/rGvblGCD7qM?t=95
  - EddieDante 4y ago
    Michael Winslow is one of the greats.
    - timbit42 4y ago
      He was on AGT a few years ago.
pavel_lishin 4y ago
I wonder what sort of spaceship would be capable of emergency deceleration at 4g for nine days, but would choose a leisurely 0.1g cruise to get up to .1c over the course of over a year instead. edit: actually, what sort of rotational rings would withstand that 4g load? Surely they'd break apart. I guess that might be part of the fun and exciting plot - the rush to move vital equipment into the core of the ship, and choosing to abandon the rings, and adapt to a week of high-g, followed by a long low-g cruise period.
- Someone 4y ago
  If power requirements as a function of acceleration/deceleration rate are above linear, it might be more economical to accelerate slowly, especially. Also, the faster acceleration/deceleration might be less comfortable, destroy cargo, wear out the engine faster, etc.
- gridspy 4y ago
  That, or when the ship was built with engines capable of delivering 4G they designed the rings to handle it. You could tether the rings to the outside of the ship (towards the nose) like a suspension bridge to support them during high thrust periods. Perhaps spinning the rings requires the tethers to be removed, or perhaps the rings must not be spinning while the engine thrust above 0.5G (because high trust locks the bearings of the rings).
throwaway09223 4y ago
If a ship is capable of continuous 1g acceleration then it shouldn't be designed with rotating centrifugal rings for gravity. Instead, design the ship with the floor towards the engine and travel at a constant 1g to wherever it is that you're going. Decelerate at the same speed.
- Mister_Snuggles 4y ago
  I'm really surprised by this oversight as other things (magnetic boots) from The Expanse were explicitly mentioned. In The Expanse, this is exactly how ships are set up. The "floor" is towards the engine and the continuous 1g acceleration provides "gravity". When a ship starts decelerating there is a "flip and burn" where everyone straps in while the ship literally turns around and starts accelerating at 1g in the opposite direction (meaning it's slowing down relative to its destination).
  - rtkwe 4y ago
    Most ships in The Expanse travel under much lower (1/6-1/2 G) accelerations because they didn't magic away all fuel consumption just made the fusion drives fantastically efficient. As you get to poorer ships more time is spent "on the float" between target and destination. Even our main character's ship doesn't accelerate all the time while travelling.
    - Akronymus 4y ago
      From what I remember, not just more efficient but also a LOT more thrust than realistic.
  - ghusbands 4y ago
    It could just flip much more slowly and maintain ~1g, with minimal course correction.
    - joncrocks 4y ago
      Presumably the mid-point is where the ship would be travelling at maximum velocity, so the course correction may not be as minimal depending on how slowly we're talking. It might be this would use more fuel/mass.
amelius 4y ago
They might want to consider diamagnetic levitation to counter g-forces: https://www.ru.nl/hfml/research/levitation-explained/diamagnetic-levitation/ https://www.ru.nl/hfml/research/levitation-explained/diamagn...
nickt 4y ago
The relativistic rocket calculator linked in the comments is quite interesting. https://gregsspacecalculations.blogspot.com/p/blog-page.html?m=1 https://gregsspacecalculations.blogspot.com/p/blog-page.html...
franky47 4y ago
One point is left out from this calculation: what's the reference point we're at a "full stop" from? Aren't you always orbiting something when in space (however large or distant)? If you were to kill your orbital (lateral) velocity, you'd only be gaining radial velocity by being pulled towards the orbiting body, some form of thrust would be needed to compensate that. TL;DR: can you really be "at a full stop" in space?
- falcolas 4y ago
  A very good point. Even if you're at a "full stop" in the frame of reference of the average of the local stellar bodies, those dust particles (asteroids, planetoids, etc) the deflector is used for aren't necessarily.
- 323 4y ago
  You could consider the start point (roughly) as the reference point. Or the destination point.
ericbarrett 4y ago
I think it would be impossible for humans to walk around at more than ~1.5 g of acceleration for extended periods of time, and even that is asking a lot. Take the g-force and multiply it by your body weight. That would be how heavy you feel when standing. If you are 70 kg (154 lbs) and under 1.5g of acceleration that is an extra 35 kg (77 lbs) of weight, which is about what we ask a modern soldier to carry. But the soldier gets to set their pack down when they rest, and the weight isn't applied to their internal organs. Perhaps gradual introduction of the acceleration over weeks would allow people to build conditioning, if all the crew is young and very fit. Go higher and it gets even less plausible. 2.0g is like carrying your twin. Surely this is impossible to sustain for more than an hour or two without some kind of acceleration couch—setting cardiac health aside entirely—and injury would be very likely if you were active.
- hoseja 4y ago
  Acceleration-added weight is carried better than a backpack. It's better distributed, the same way the rest of your normal weight is distributed, just more of it.
- ginko 4y ago
  >Go higher and it gets even less plausible. 2.0g is like carrying your twin. FWIW there are people who weigh well beyond 150kg so I'd argue it would be plausible. Will people be able to perform at peak physical level? No. Will they probably manage for a couple of days? I'd say so.
  - TremendousJudge 4y ago
    It's not the same though. When at higher gravity, you're not carrying more weight like a backpack or like extra fat -- your regular tissues weigh more. This includes your blood and other fluids, but your heart is still the same strength. I'd expect that to make a difference.
    - hammock 4y ago
      That’s a really interesting point. I wonder if there are “artificial exohearts” or something that we could install on the extremities to keep vital body fluids like blood and lymph flowing when the heart is not strong enough.
jimbokun 4y ago
In this book, a space flight to Alpha Centauri uses an asteroid which is constantly accelerated at 1g for half the flight, then constantly decelerates at 1g for the second half of the trip: https://en.wikipedia.org/wiki/The_Sparrow_(novel) https://en.wikipedia.org/wiki/The_Sparrow_(novel) That eliminates need for "artificial gravity" and really drove home to me that 1g is really the limiting factor for long range human space flight.
- dhc02 4y ago
  Love that book.
  - jimbokun 4y ago
    I love it and hate it. Beautiful and brilliant, and combines religion with sci-fi without demonizing the religious characters. But events later in the book, while completely consistent with the premise, were pretty gut wrenching to read.
- throwaway09223 4y ago
  1g isn't all that limiting. Under 1g acceleration you'll reach lightspeed in about a year, at which point you can't go any faster. A year to reach the top speed of the universe isn't so bad. The truly limiting factor is that we don't have engines that can produce 1g for a sustained period. We can't carry and propel enough reaction mass and reactionless drives only exist in science fiction.
  - jefftk 4y ago
    > you'll reach lightspeed in about a year, at which point you can't go any faster I don't think that's how relativity works?
    - scrumbledober 4y ago
      assuming constant acceleration it kinda does, but constant acceleration requires asymptotic infinite amounts of energy.
KineticLensman 4y ago
I think this illustrates how hard it is to write SF plots involving 'mundane' interstellar travel (no warp drives or wormholes) that make approximate sense in terms of the laws of physics but which also reflect the enormous energy required and the sheer complexity of the task. Going to a different star is nothing like going to the moon but with a much larger Apollo. Simple plot devices (there's something in the way that we didn't detect before launch and didn't otherwise consider) really don't stand up very well.
- jrlowe 4y ago
  Yes, I completely appreciate the handwaving that sci-fi authors regularly do to avoid having to switch to the character's great-greatX1000 grandchild upon arrival to Alpha Centauri....on page 2 of 500!
verisimi 4y ago
How do you brake in a vacuum? There's no air resistance, nothing to create friction.
- dreamcompiler 4y ago
  You use thrust to decelerate. Same thing you use to accelerate.
- Rastonbury 4y ago
  Flip the ship around and thrust
- avhon1 4y ago
  It's not a perfect vacuum out there, there is an interstellar medium. You could create non-negligible drag with a huge sail or magnetic field, like a Bussard Ramjet. https://en.wikipedia.org/wiki/Bussard_ramjet https://en.wikipedia.org/wiki/Bussard_ramjet
  - hallway_monitor 4y ago
    I was looking for this as I have always seen the ramjet as the only feasible possibility for non-magical long-term propulsion. Of course that's if we don't find a way to trick the universe into FTL travel.
paulsutter 4y ago
>The two most unscientific words in Star Trek are probably "full stop" Such a promising article, and then they completely miss the mark THERE IS NO SUCH THING AS A FULL STOP IN SPACE. There is no frame of refernece to stop against. It's completely meaningless, and has nothing to do with limitations of deceleration
- nomel 4y ago
  Oh, that’s silly, for a practical context, which flying a spaceship would be. Practically, it would be relative to the nearest large body/galaxy/pair, and depend on context, which would almost always be understood. For example, if you’re observing a planet, full stop would be relative to that planet.
  - paulsutter 4y ago
    So full stop means either go to geosynchronous orbit or fall to the surface?
    - nomel 4y ago
      Since human occupied spaceships are never meant to fall from space, except for the illegal suicide vessels found near Vermiticus 4, I think the practical answer would be geosynchronous orbit.
- spuz 4y ago
  Presumably at those speeds, the frame of reference would be the galaxy and the interstellar material in which the ship travels. If your ship were to match the average speed of this material, then you could claim to be at a stop. If the concern was to prevent damage due to collision with this material, then it makes sense that in order to "stop" you would actually have to match the speed of the material that you are moving through.
- jcrawfordor 4y ago
  This really all stems from a misunderstanding of what "full stop" or "all stop" (all engines, for vessels that commonly operate only some engines for cruising) means. "full stop" is a position on the engine telegraph that tells engineering to stop the engine or take it out of gear, depending on the type of propulsion setup. It has nothing to do with the speed of the ship relative to anything, after the "full stop" order is given the ship will continue to move forwards by momentum. If the captain actually wants to stop as soon as possible they will order "full astern," which signals engineering to run the engine in reverse at normal full speed, effectively braking. Because oceangoing ships stop on their own reasonably quickly this is usually more of an emergency maneuver. The fact that motion is relative is already quite true at sea in our own world, where in at-sea operations your position relative to other vessels can matter much more than your position relative to the earth. In other words this issue is not at all new or specific to space. More basically, though, today and presumably centuries into the future "full stop" is not an order to stop the ship, it's an order to stop the engine. The order is "full stop" because large marine engines are traditionally directly coupled to the propshaft and cannot "idle" per se. On these types of systems, still common on large vessels, there is some nuance depending on the engine setup between "standby," "stop," and "finished" which are traditionally all positions on the engine telegraph that do more or less the same thing but give different instructions to the engineer operating the engine as far as preparations for the near future. On top of this most ships today the "engine telegraph" is not really used when underway and the telegraph sender on the bridge actually controls the engine directly via automation, but usually this only allows for speed changes and not stopping or reversing, which still requires that engineering take over engine control due to the preparations and checks that must be done when stopping and starting the engine. Rather than telegraph bells this is more likely to be a phone call these days.
i_like_apis 4y ago
In Star Trek they had "inertial dampeners".
- waste_monk 4y ago
  From Memory Alpha: 'According to the Star Trek Encyclopedia (2nd ed., p. 205), inertial dampers were "invented" by Star Trek writers to explain how the crew avoided becoming "chunky salsa" when starships accelerated or decelerated. ' [1] and further list them as a requirement to achieve warp. I would imagine that "merely" instantly decelerating from 0.25c to a dead stop would be trivial in comparison. [1] https://memory-alpha.fandom.com/wiki/Inertial_damping_system https://memory-alpha.fandom.com/wiki/Inertial_damping_system
sydthrowaway 4y ago
WHen are we going to get a new Einstein to sort all this out. Surely, we can start putting some neural enhancers in baby formula.
luis8 4y ago
What about using a long ship and then using a high tech spring to apply the deceleration over the length of it. Relocate the passenger at the front and repeat until you reached the desired speed. Just thinking out loud maybe that will be counterproductive in the amount of time needed
- Valgrim 4y ago
  This reminds me of the device used in Jules Vernes " From the Earth to the Moon". The projectile has "thick lining of leather fastened on springs of best steel", together with some sort of hydraulic system, meant to absorb the shock of shot.
mrtweetyhack 4y ago
hoseja 4y ago
He mentions Expanse and yet not the smart "skyscraper" design of it's ships? Where the engines push from the "bottom" (decks-wise), not from the back as in a literal seaship. With that arrangement, the issues of "back wall is suddenly the floor" disappear.
amai 4y ago
The problem of deceleration was already „solved“ in the classic movie Forbidden Planet from 1956: https://youtu.be/78nbTCgkYn4 https://youtu.be/78nbTCgkYn4
picsao 4y ago

57 points by sklargh 4y ago

> Can humans withstand 4 g non-stop for 9 days? They might if you keep rotating them, so the force is not along one axis all the time.

jermaustin1 4y ago
Seems like that would cause terrible motion sickness. Rotating would cause centripetal force, so another vector of acceleration on your body PLUS a constantly changing vector of acceleration due to deceleration.
- tantalor 4y ago
  I imagine amelius intended a regular "flip" like a hospitalized patient to avoid bedsores, not constant rotation.
  - dTal 4y ago
    Immersed in liquid would be the way. Internal organs would still have to bear the load, but your skeleton and musculature could be spared.

EddieDante 4y ago

The phrase "raspberry jam delta-v" comes to mind. Also, the obligatory clip from Spaceballs... https://www.youtube.com/watch?v=NAWL8ejf2nM https://www.youtube.com/watch?v=NAWL8ejf2nM

xeromal 4y ago
This specific moment where he still makes the noise after having the microphone smacked from him makes me laugh the same as it did when I was a tiny kid. https://youtu.be/rGvblGCD7qM?t=95 https://youtu.be/rGvblGCD7qM?t=95
- EddieDante 4y ago
  Michael Winslow is one of the greats.
  - timbit42 4y ago
    He was on AGT a few years ago.

pavel_lishin 4y ago

I wonder what sort of spaceship would be capable of emergency deceleration at 4g for nine days, but would choose a leisurely 0.1g cruise to get up to .1c over the course of over a year instead. edit: actually, what sort of rotational rings would withstand that 4g load? Surely they'd break apart. I guess that might be part of the fun and exciting plot - the rush to move vital equipment into the core of the ship, and choosing to abandon the rings, and adapt to a week of high-g, followed by a long low-g cruise period.

Someone 4y ago
If power requirements as a function of acceleration/deceleration rate are above linear, it might be more economical to accelerate slowly, especially. Also, the faster acceleration/deceleration might be less comfortable, destroy cargo, wear out the engine faster, etc.
gridspy 4y ago
That, or when the ship was built with engines capable of delivering 4G they designed the rings to handle it. You could tether the rings to the outside of the ship (towards the nose) like a suspension bridge to support them during high thrust periods. Perhaps spinning the rings requires the tethers to be removed, or perhaps the rings must not be spinning while the engine thrust above 0.5G (because high trust locks the bearings of the rings).

throwaway09223 4y ago

If a ship is capable of continuous 1g acceleration then it shouldn't be designed with rotating centrifugal rings for gravity. Instead, design the ship with the floor towards the engine and travel at a constant 1g to wherever it is that you're going. Decelerate at the same speed.

Mister_Snuggles 4y ago
I'm really surprised by this oversight as other things (magnetic boots) from The Expanse were explicitly mentioned. In The Expanse, this is exactly how ships are set up. The "floor" is towards the engine and the continuous 1g acceleration provides "gravity". When a ship starts decelerating there is a "flip and burn" where everyone straps in while the ship literally turns around and starts accelerating at 1g in the opposite direction (meaning it's slowing down relative to its destination).
- rtkwe 4y ago
  Most ships in The Expanse travel under much lower (1/6-1/2 G) accelerations because they didn't magic away all fuel consumption just made the fusion drives fantastically efficient. As you get to poorer ships more time is spent "on the float" between target and destination. Even our main character's ship doesn't accelerate all the time while travelling.
  - Akronymus 4y ago
    From what I remember, not just more efficient but also a LOT more thrust than realistic.
- ghusbands 4y ago
  It could just flip much more slowly and maintain ~1g, with minimal course correction.
  - joncrocks 4y ago
    Presumably the mid-point is where the ship would be travelling at maximum velocity, so the course correction may not be as minimal depending on how slowly we're talking. It might be this would use more fuel/mass.

amelius 4y ago

They might want to consider diamagnetic levitation to counter g-forces: https://www.ru.nl/hfml/research/levitation-explained/diamagnetic-levitation/ https://www.ru.nl/hfml/research/levitation-explained/diamagn...

nickt 4y ago

The relativistic rocket calculator linked in the comments is quite interesting. https://gregsspacecalculations.blogspot.com/p/blog-page.html?m=1 https://gregsspacecalculations.blogspot.com/p/blog-page.html...

franky47 4y ago

One point is left out from this calculation: what's the reference point we're at a "full stop" from? Aren't you always orbiting something when in space (however large or distant)? If you were to kill your orbital (lateral) velocity, you'd only be gaining radial velocity by being pulled towards the orbiting body, some form of thrust would be needed to compensate that. TL;DR: can you really be "at a full stop" in space?

falcolas 4y ago
A very good point. Even if you're at a "full stop" in the frame of reference of the average of the local stellar bodies, those dust particles (asteroids, planetoids, etc) the deflector is used for aren't necessarily.
323 4y ago
You could consider the start point (roughly) as the reference point. Or the destination point.

ericbarrett 4y ago

I think it would be impossible for humans to walk around at more than ~1.5 g of acceleration for extended periods of time, and even that is asking a lot. Take the g-force and multiply it by your body weight. That would be how heavy you feel when standing. If you are 70 kg (154 lbs) and under 1.5g of acceleration that is an extra 35 kg (77 lbs) of weight, which is about what we ask a modern soldier to carry. But the soldier gets to set their pack down when they rest, and the weight isn't applied to their internal organs. Perhaps gradual introduction of the acceleration over weeks would allow people to build conditioning, if all the crew is young and very fit. Go higher and it gets even less plausible. 2.0g is like carrying your twin. Surely this is impossible to sustain for more than an hour or two without some kind of acceleration couch—setting cardiac health aside entirely—and injury would be very likely if you were active.

hoseja 4y ago
Acceleration-added weight is carried better than a backpack. It's better distributed, the same way the rest of your normal weight is distributed, just more of it.
ginko 4y ago
>Go higher and it gets even less plausible. 2.0g is like carrying your twin. FWIW there are people who weigh well beyond 150kg so I'd argue it would be plausible. Will people be able to perform at peak physical level? No. Will they probably manage for a couple of days? I'd say so.
- TremendousJudge 4y ago
  It's not the same though. When at higher gravity, you're not carrying more weight like a backpack or like extra fat -- your regular tissues weigh more. This includes your blood and other fluids, but your heart is still the same strength. I'd expect that to make a difference.
  - hammock 4y ago
    That’s a really interesting point. I wonder if there are “artificial exohearts” or something that we could install on the extremities to keep vital body fluids like blood and lymph flowing when the heart is not strong enough.

jimbokun 4y ago

In this book, a space flight to Alpha Centauri uses an asteroid which is constantly accelerated at 1g for half the flight, then constantly decelerates at 1g for the second half of the trip: https://en.wikipedia.org/wiki/The_Sparrow_(novel) https://en.wikipedia.org/wiki/The_Sparrow_(novel) That eliminates need for "artificial gravity" and really drove home to me that 1g is really the limiting factor for long range human space flight.

dhc02 4y ago
Love that book.
- jimbokun 4y ago
  I love it and hate it. Beautiful and brilliant, and combines religion with sci-fi without demonizing the religious characters. But events later in the book, while completely consistent with the premise, were pretty gut wrenching to read.
throwaway09223 4y ago
1g isn't all that limiting. Under 1g acceleration you'll reach lightspeed in about a year, at which point you can't go any faster. A year to reach the top speed of the universe isn't so bad. The truly limiting factor is that we don't have engines that can produce 1g for a sustained period. We can't carry and propel enough reaction mass and reactionless drives only exist in science fiction.
- jefftk 4y ago
  > you'll reach lightspeed in about a year, at which point you can't go any faster I don't think that's how relativity works?
  - scrumbledober 4y ago
    assuming constant acceleration it kinda does, but constant acceleration requires asymptotic infinite amounts of energy.

KineticLensman 4y ago

I think this illustrates how hard it is to write SF plots involving 'mundane' interstellar travel (no warp drives or wormholes) that make approximate sense in terms of the laws of physics but which also reflect the enormous energy required and the sheer complexity of the task. Going to a different star is nothing like going to the moon but with a much larger Apollo. Simple plot devices (there's something in the way that we didn't detect before launch and didn't otherwise consider) really don't stand up very well.

jrlowe 4y ago
Yes, I completely appreciate the handwaving that sci-fi authors regularly do to avoid having to switch to the character's great-greatX1000 grandchild upon arrival to Alpha Centauri....on page 2 of 500!

verisimi 4y ago

How do you brake in a vacuum? There's no air resistance, nothing to create friction.

dreamcompiler 4y ago
You use thrust to decelerate. Same thing you use to accelerate.
Rastonbury 4y ago
Flip the ship around and thrust
avhon1 4y ago
It's not a perfect vacuum out there, there is an interstellar medium. You could create non-negligible drag with a huge sail or magnetic field, like a Bussard Ramjet. https://en.wikipedia.org/wiki/Bussard_ramjet https://en.wikipedia.org/wiki/Bussard_ramjet
- hallway_monitor 4y ago
  I was looking for this as I have always seen the ramjet as the only feasible possibility for non-magical long-term propulsion. Of course that's if we don't find a way to trick the universe into FTL travel.

paulsutter 4y ago

>The two most unscientific words in Star Trek are probably "full stop" Such a promising article, and then they completely miss the mark THERE IS NO SUCH THING AS A FULL STOP IN SPACE. There is no frame of refernece to stop against. It's completely meaningless, and has nothing to do with limitations of deceleration

nomel 4y ago
Oh, that’s silly, for a practical context, which flying a spaceship would be. Practically, it would be relative to the nearest large body/galaxy/pair, and depend on context, which would almost always be understood. For example, if you’re observing a planet, full stop would be relative to that planet.
- paulsutter 4y ago
  So full stop means either go to geosynchronous orbit or fall to the surface?
  - nomel 4y ago
    Since human occupied spaceships are never meant to fall from space, except for the illegal suicide vessels found near Vermiticus 4, I think the practical answer would be geosynchronous orbit.
spuz 4y ago
Presumably at those speeds, the frame of reference would be the galaxy and the interstellar material in which the ship travels. If your ship were to match the average speed of this material, then you could claim to be at a stop. If the concern was to prevent damage due to collision with this material, then it makes sense that in order to "stop" you would actually have to match the speed of the material that you are moving through.
jcrawfordor 4y ago
This really all stems from a misunderstanding of what "full stop" or "all stop" (all engines, for vessels that commonly operate only some engines for cruising) means. "full stop" is a position on the engine telegraph that tells engineering to stop the engine or take it out of gear, depending on the type of propulsion setup. It has nothing to do with the speed of the ship relative to anything, after the "full stop" order is given the ship will continue to move forwards by momentum. If the captain actually wants to stop as soon as possible they will order "full astern," which signals engineering to run the engine in reverse at normal full speed, effectively braking. Because oceangoing ships stop on their own reasonably quickly this is usually more of an emergency maneuver. The fact that motion is relative is already quite true at sea in our own world, where in at-sea operations your position relative to other vessels can matter much more than your position relative to the earth. In other words this issue is not at all new or specific to space. More basically, though, today and presumably centuries into the future "full stop" is not an order to stop the ship, it's an order to stop the engine. The order is "full stop" because large marine engines are traditionally directly coupled to the propshaft and cannot "idle" per se. On these types of systems, still common on large vessels, there is some nuance depending on the engine setup between "standby," "stop," and "finished" which are traditionally all positions on the engine telegraph that do more or less the same thing but give different instructions to the engineer operating the engine as far as preparations for the near future. On top of this most ships today the "engine telegraph" is not really used when underway and the telegraph sender on the bridge actually controls the engine directly via automation, but usually this only allows for speed changes and not stopping or reversing, which still requires that engineering take over engine control due to the preparations and checks that must be done when stopping and starting the engine. Rather than telegraph bells this is more likely to be a phone call these days.

i_like_apis 4y ago

In Star Trek they had "inertial dampeners".

waste_monk 4y ago
From Memory Alpha: 'According to the Star Trek Encyclopedia (2nd ed., p. 205), inertial dampers were "invented" by Star Trek writers to explain how the crew avoided becoming "chunky salsa" when starships accelerated or decelerated. ' [1] and further list them as a requirement to achieve warp. I would imagine that "merely" instantly decelerating from 0.25c to a dead stop would be trivial in comparison. [1] https://memory-alpha.fandom.com/wiki/Inertial_damping_system https://memory-alpha.fandom.com/wiki/Inertial_damping_system

sydthrowaway 4y ago

WHen are we going to get a new Einstein to sort all this out. Surely, we can start putting some neural enhancers in baby formula.

luis8 4y ago

What about using a long ship and then using a high tech spring to apply the deceleration over the length of it. Relocate the passenger at the front and repeat until you reached the desired speed. Just thinking out loud maybe that will be counterproductive in the amount of time needed

Valgrim 4y ago
This reminds me of the device used in Jules Vernes " From the Earth to the Moon". The projectile has "thick lining of leather fastened on springs of best steel", together with some sort of hydraulic system, meant to absorb the shock of shot.

mrtweetyhack 4y ago

hoseja 4y ago

He mentions Expanse and yet not the smart "skyscraper" design of it's ships? Where the engines push from the "bottom" (decks-wise), not from the back as in a literal seaship. With that arrangement, the issues of "back wall is suddenly the floor" disappear.

amai 4y ago

The problem of deceleration was already „solved“ in the classic movie Forbidden Planet from 1956: https://youtu.be/78nbTCgkYn4 https://youtu.be/78nbTCgkYn4

picsao 4y ago