Naked Science Forum
Non Life Sciences => Technology => Topic started by: Logan the wise on 15/12/2017 02:53:37
-
Basically I had an idea and I wondered about if it could be true . If you use the same polar side of a magnet we know they repel each other . Could this be used for space travel?
-
In principle, you could use a magnetic launch system to accelerate a space ship to very high speeds. The proposed StarTram system is one such proposal: https://en.wikipedia.org/wiki/StarTram (https://en.wikipedia.org/wiki/StarTram). However, you'd need to carry some kind of propulsion system on board if you planned on steering or slowing down at some point.
-
So would flaps similar to the ones on airplanes not work ? Because there is no drag? Also let's say the whole ship is a giant magnet. Could we shoot let's call them magnet bases around space at different place for the ship to stop adujust flight path and then launch again . Think along the lines of a connect the dots picture with the dots being magnets and the line is the ship
-
I do understand it would need some secondary engines for avoiding unforeseen obstructions in the flight path (asteroids,etc) and planetary exploration .
-
Space is practically a vacuum, so conventional aircraft control surfaces wouldn't work.
Your idea for magnetic space bases accelerating and decelerating magnetized spacecraft would work in principle, but it would probably be impractical in practice. Pushing a magnetized spacecraft up to the velocities typical of chemical-powered rockets would require very long magnetic tracks (in the case of StarTram, it would be many miles long). Those tracks, in turn, would require massive amounts of power to operate. Then you'd have to have the extreme precision needed to land your greatly hypersonic spacecraft on an opposing track at your destination that decelerates you at about the same rate that you were initially accelerated to bring to safely to a full stop. You would need some way to do this consistently and safely. It's also limiting in the sense that you can't send your space ship anywhere that a base hasn't already been built, whereas a chemical rocket could.
If this track was on a base located in outer space, then the very act of landing would push the base and change its velocity. It would need to have some way of compensating for this change with on board thrusters or something similar. It would all be a very expensive undertaking.
-
But from what I understand in space you wouldn't need the tracks because there isn't drag to over come in space ,right? So wouldn't the first time the same poles push on each other be enough to push it through space? I guess I should have ask what is the speed that magnets repel each other? And I would think it would make more sense for the ship to slow itself with front thruster . And I would use the same principle that sends the ship to send new base pads . And I agree that it would be expensive but that's the cost of the future assuming that mag lift technology is the future
-
So wouldn't the first time the same poles push on each other be enough to push it through space?
Yes, they would push on each other - but if you have ever used a magnet as a compass, you would know that the Earth's magnetic field is very weak, so the force of repulsion is very low.
There are other places where the magnetic field is stronger, such as the vicinity of Jupiter or the Sun. But you have to get there, first, and repulsion from Earth's magnetic field is not going to achieve that!
In fact, "like poles oppose, opposite poles attract", as we learnt in high school.
- So there is not just repulsion, there is attraction, too, towards the opposite pole. This almost cancels the repulsion.
- The force felt by the magnet is not primarily one of repulsion, but rotation, to line up the opposite poles.
- If you try to oppose the rotation, you would use more fuel than if you just used a rocket to accelerate your space probe.
In fact, permanent magnets are used to orient small satellites in Low Earth Orbit, where Earth's magnetic field is strongest. Electromagnets may be used for slightly larger satellites.
- Compared to gyroscopes/reaction wheels, magnets don't have any moving parts.
- Magnets are not usable in geosynchronous orbit, because Earth's magnetic field is too weak.
See more at: https://en.wikipedia.org/wiki/Magnetorquer
-
It might be possible to use magnets to push off the solar wind. The solar wind is a plasma, which is basically a conductive fluid that is flowing away from the Sun very, very fast. There's been some work on trying to use it for propulsion using magnets to push on it. However, the schemes that have been proposed (MagSail and M2P2) don't appear to work very well. I did some work on a scheme that possibly showed more promise, but I don't know how to accurately model the plasma, so checking that it works is tricky.
-
There is no drag, but there sure is gravity!
The magnets would have to overcome the gravitational attraction of whatever moon, planet, star, etc. you are leaving behind.
Also, just setting up two opposing magnets will not allow them to push on each other at any distance. The interaction between two magnetic dipoles falls off very quickly (you can feel this with two fairly strong neodymium magnets that you can hold in your hands--when close together, the magnets interact very strongly, but once they are more than shoulder-width apart, the force is only just noticeable... by the time the magnets are on opposites ends of the room there is basically no interaction; so how big would the magnets need to be to keep pushing all the way to the international space station, which is about 100 km up?)
-
That's true, magnetic fields are short-range, they only have good strength when the distance is of order the size of the magnet (or so).
But you can have a line of magnets, preferably electromagnets.
That's the principle behind space fountains, orbital rings and launch loops:
https://en.wikipedia.org/wiki/Space_fountain
https://en.wikipedia.org/wiki/Orbital_ring
https://en.wikipedia.org/wiki/Launch_loop
-
That's true, magnetic fields are short-range, they only have good strength when the distance is of order the size of the magnet (or so).
But you can have a line of magnets, preferably electromagnets.
That's the principle behind space fountains, orbital rings and launch loops:
https://en.wikipedia.org/wiki/Space_fountain
https://en.wikipedia.org/wiki/Orbital_ring
https://en.wikipedia.org/wiki/Launch_loop
Agreed. If there is is a track to go along then magnetic propulsion can continue to deliver acceleration, but in deep space this approach will not be feasible.
-
Agreed. If there is is a track to go along then magnetic propulsion can continue to deliver acceleration, but in deep space this approach will not be feasible.
Bob Forward proposed using a long wire-like structure, where you accelerate a vehicle along it magnetically.
-
Hi guys, Christmas greetings from Goa India to all people at the Nakedscientists forum.
Just a quick message to all the magnetic propulsion investigators, please do your math first, than let your imagination flow.
Happy New Year.