What if you took the principle of magnetic acceleration, created a bunch of acceleration gateways in space, and then shot space trains through it? Have catching gates on the opposite end for the deceleration part.
What's the maximum speed that magnetic acceleration can accelerate an object to in a vacuum before the object is travelling so fast that the magnetic effect can no longer impact upon it as it passes the gates?
I wanna build some fucking space trains. What can I read that's explored this?
The rings would have to be attached to something, or else they'd go flying in the opposite direction.
There have been a few proposals to use electromagnets to launch things into space, including a maglev train called the StarTram: https://en.wikipedia.org/wiki/StarTram
What if we built a large hadron collider but instead of a single particle being accelerated around the circle we instead accelerated an entire fucking train? Build the circle around the entire planet or even bigger if you have to. Loop it until you can't anymore and then blast it off out there.
Build one on the receiving end too and physically catch the train in it to decelerate. Use loops like LHC does for particle acceleration.
EDIT: If you built them as rings could you not convert the launching energy into spinning energy instead and offset the fact it's not physically attached to a planet? @Bobson_Dugnutt
You're basically describing a mass driver . It doesn't need to go around the whole planet and it still needs rockets at the end to get into orbit or to other planets. It does remove the need for a first stage which is the biggest stage in terms of mass and fuel consumption. Rocket engines that can be used in space are much more efficient than ones that can be used on Earth or other planets with thick atmospheres.
I think you might be interested in an Aldrin Cycler . It's a big space station that would go close to both earth and mars using natural orbital mechanics so it doesn't need to use any fuel. The idea is that all the big heavy long-term life support equipment would go on the Aldrin Cycler while the people going between Earth and Mars would just need a small spacecraft with just enough life support and fuel to get to the Aldrin Cycler. It's also like a train in that we can put a bunch of them on similar orbital "tracks" so if you miss one you can catch the next one.
So the path would be as follows: wait for the Aldrin Cycler to be in the correct position, mass driver sends you from Earth to space, high-efficiency rocket propulsion to orbit, another rocket burn to the Aldrin Cycler, stay in the Aldrin Cycler until it gets to Mars, get out of the Aldrin Cycler and back into your small spacecraft and then do a rocket burn to Mars (or one of Mars' moons).
you could do a ring a little bit bigger or smaller than earth’s orbit. at that radius the centrifugal force from orbiting near c would be pretty mild. sunlight takes ~8 min to reach earth, so one trip around the ring at near-c would be like 25 min. getting a human up to that speed would take a long time though. at one gee of acceleration you’d need around a year to approach lightspeed unless i fucked up the math.
now you have a really fast spinny thing and good luck timing your approach with the start of the catching tube
That's fine if it's also the catching station, when it decelerates an incoming shuttle the deceleration will provide the same energy in the opposite direction.
the traffic may not be equal going both ways at all times, especially as spaceflight in the solar system will be centered upon earth for quite a while because thats where all the people and industrial capacity are, outbound flights will exceed incoming flights.
the loop itself doesn't need to spin. also, i think you could have the loop not care where on the loop a projectile enters or exits from, or at least have lots of potential spots.
yes that may work, but if its something built in like a reaction wheel it will accumulate angular momentum until whatever bearing its rotating on gives out, it would also have to be launch in an equal and opposite direction, perhaps launching one payload towards the outer solar system and another towards the inner solar system, since one needs to lose velocity and the other needs to gain it (relative to their path around the sun)
perhaps another way would to do the catching at the same time as the throwing, so for each payload sent another of similar mass must arrive, this is less feasible for as long as earth is the center of human space capability because thingd outbound from earth will outnumber those arriving.
maybe one launch accelerates a countermass (*around the ring) and the next launch goes round (*the ring) the other way and decelerates the countermass back to rest (*within the ring)
you still gotta account for the linear momentum imparted to the ring when the ship leaves though.
i think the linear momentum is also canceled out by the counterweight launch, but if youre relying on a second station to catch the counterweight youre also relying on another launch to act as counterweight to the counterweight. if shipment is late or theres no shipment available youre either not catching your counterweight and its gone or you have tons of angular or linear velocity now. and if you have means to store angular velocity (eg big reaction wheels) for when the next payload arrives you can do all that with a single station.
oh I didn't mean launch the counterweight, I was imagining that the counterweight does nothing but get pushed around the ring one way or another.
if the ring is centered around the sun, maybe a bit bigger or smaller than earth's orbit, you could control big solar sails on the ring to get rid of unwanted linear momentum.
were thinking on very different scales, i was thinking interplanetary launchers between earth and mars, youre thinking interstellar travel. and yes solar sails on that scale would work to remove momentum
There's a startup working on a centrifuge that would launch rockets, so something like what you described is possible: https://www.thedrive.com/the-war-zone/43079/space-launch-start-up-just-used-a-giant-centrifuge-to-hurl-a-projectile-into-the-upper-atmosphere
Really reminds me of this gem from Mass Effect. This is definitely a viable form of space travel and has been proposed. The main issues are maintaining the location of your acceleration/deceleration gates and that you'd have to make it to your destination using other means of propulsion first. The guy's politics are pretty cringe, but there's good information on stuff like this on the "Science and Futurism with Isaac Arthur" YouTube channel.
I don't think there is any maximum speed for mass drivers besides the speed of light. If you put a net force on an object it will accelerate regardless of how fast its already going.
Perhaps we could build a time machine train on the moon using a mass driver along its entire circumference. You enter the train, the train accelerates up to near the speed of light and circles the moon about 27.4 times per second, and a few hours later it decelerates and you get off. But due to time dilation that few hours for you was years to the rest of the universe and so you've completed a one way journey into the future.
Edit: thinking about that a little more, the centrifugal force would probably result in you getting smeared all over the roof of the train. This is probably better done in a straight line
It's more the force of acceleration, rather than any centripetal forces, that would get you. You have to accelerate to near c over around 100 hours and decelerate over the same period of time. That's assuming the human body can withstand 6g for four days straight.
Yeah, the time scale I talked about would cause you to become a pancake.
At one g constant acceleration you'd reach near the speed of light after about a year. But I don't think anyone wants to spend a year inside a train-like vehicle
when we start talking about interstellar ships moving at near light speed, i think we can stop worrying about making them resemble trains. the ship is probably the size of mt everest and consists mostly of shielding. also, at this stage in technological development, we'll probably be pretty long-lived and able to mess with our own biology in a sophisticated way, so not only is a long trip between stars a smaller chunk of our lifespan but we can mentally adapt ourselves to the trip, e.g. superhuman memories and imaginations so a century ago feels like yesterday and your relationships with the people you leave behind don't fade in your mind over that timescale
It would take over 1400 hours to reach the speed of light at 6g by my calculations.
i posted this in another comment, but:
you could do a ring a little bit bigger or smaller than earth’s orbit. at that radius the centrifugal force from orbiting near c would be pretty mild. sunlight takes ~8 min to reach earth, so one trip around the ring at near-c would be like 25 min. getting a human up to that speed would take a long time though. at one gee of acceleration you’d need around a year to approach lightspeed unless i fucked up the math.
one issue is hitting stuff. on a multi-lightyear trip you are gonna hit a lot of gas and dust and other miscellaneous space crud, and at near-lightspeed those impacts are gonna be really high energy.
I think the bigger question is where the space tracks start and end. The origins and destinations for space travel would need to stay in the same relative locations in 3 dimensions and all that, so planets are right out.
i think you'd need an aimable train-launcher at either end and some way to clear stuff out of the way between them
Yeah, mass drivers and such have been a staple if scifi since forever. Big electric coil-gun at one end and a catcher-station at the end. Usually not train-shaped, but no reason they couldn't be.
Pusher stations in the middle are more complicated, because of the recoil issues. You could probably get around it by getting clever/cute and putting the midway-stations in orbit around a body with a magnetic field. Boost the train and re-circularize your orbit magnetically by pushing off the parent body. A lot of rotovators and other hypothetical tether-launch systems work on the same idea.
I mean a version of this idea exists where essentially a big railgun thing would be used to launch stuff from the moon or anywhere with no atmosphere and low gravity. Where I heard about it was a video from kurzgesagt but theres probably better out there.
the problem would never be the projectile becoming too fast to impart motion onto, just make the gun barrel longer. the real problem is your space gun will be absorbing all those changes in velocity, if it is launching things and adding speed to them, that speed will be taken from the gun, if it is catching things and slowing them down that speed will be added to the gun. eventually your expensive space gun is slowed to falling back into the atmosphere or sped up to leaving earths sphere of influence.
What if you had A LOT of separate small stations and they all only exert a very small acceleration force. This acceleration force is negligible upon each acceleration station but upon the accelerating object they all cumulatively add up. So each station is really only moved a very small amount in the other direction but the object itself is accelerated a lot cumulatively.
good luck getting all the orbits to line up, the path spacecraft take through space is not a straight line, and a spacecraft cannot sit in one place unmoving (bar a select few places which small amounts of force will dislodge them from)
I know that electromagnetism is one of the fundamental forces along with gravity, weak nuclear force (fission), and strong nuclear force (fusion). Gravity is the weakest force, but has infinite range. If you had two sugar cubes on the opposite ends of an empty universe, the smaller one will be drawn to the bigger one.
I think if you take out friction with the vacuum of space, I'd say the biggest complications would come from parts degrading and gravity skewing things in currently imperceptible ways.
Technically they both act each other, it's not just more massive body acting on the less massive one. A planet's action on its host star is one way to locate exoplanets.
Oh shit. I thought that was the case, but second-guessed myself. Thanks!
If it helps, it's best not to think of one object "pulling" on another. The easiest way to conceptualize gravity is to picture a sheet of fabric stretched out. If you place a bowling ball and a tennis ball on the fabric both objects will cause the shape of the fabric to change. The bowling ball, being the more massive object, causes more perturbation, but the effect of the tennis ball still exists.
all the four forces act across the universe, they just drop off in strength at different rates, and gravity drops off with distance the slowest so thats what tends to dominate at planetary scales. and the larger object is not solely pulling the smaller object, the small object will pull on the large one as well
Gravity and Electromagnetism drop off with at the same rate (they're both inverse square laws), but distributions of electric charge tend to even out (opposing charges attract and form a net-zero charge) at interstellar scales whereas mass is only additive and can't cancel out.
that makes sense but how do the strong and weak nuclear force fit into this? because on an atomic scale they dominate the interactions to the point gravity and magnetism are irrelevant and protons can be shoved together despite being positive, yet at larger scales they are absolutely irrelevant.
That's a brilliant idea. Just shooting trains into space along giant magnetic rings instead of rails.
Then you can have connecting rings or change other rings in advance to change course.
Singular rockets or ships would never work for a space faring society.
Building a giant track and rings and powering them all seems insanely inefficient, compared to a fission rocket, and a cyro chamber that fills with foam so your body can withstand the 100g burn when you slow down. Unless this is just a planetary thing.
I think a single fission rocket with those rings built into the cylinder of the rocket might work.
As it hurtles through space towards a destination, it releases a ring (maybe solar powered) until reaching an end point.
In that scenario, if you can plot a course for a fission rocket that takes several years, repeat trips along the same path would be easier.
you run into problems with fuel mass when you attempt to take any kind of rocket up to near-c. https://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation
one way around this that i've seen is to set up relays of giant lasers to boost solar sail ships
Exactly! Like the Large Hadron Collider but instead of particles getting looped for acceleration you do space trains instead.
You might want to consider not using trains in space due energy requirements on excellrating and decelerating, same issue with interstellar travel where you hit your max speed then have to start slowing down when your not even half way to your destination. The big limit is the human brain and g forces.
