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/sci/ - Science & Math

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6313744 No.6313744 [Reply] [Original]

Just watch gravity - (probably dumb) question for you guys

The earths magnetic field extends pretty far into space right?

Would it be possible to use rotating magnets or some electromagnet kind of like a "magnetic sail" as propulsion eliminating the need for some sort of mass to push off of?

>magnets

>> No.6313746

>>6313744
my eyes

>> No.6313748

>>6313744

it's pretty darn weak

>> No.6313752

goddamn Sandra Bullock's character in this movie was the most consistently useless person ever.

>> No.6313755

>>6313748
Even though its weak, couldn't you pump enough power into a magnet to get a reasonable amount of thrust? Like say you had a nuclear reactor up there and used it purely for this magnet sail thing

>> No.6313760

>>6313755

maybe, do the math, figure it out, become a trillionaire and space travel pioneer

>> No.6313767

>>6313760
It seems possible right?
I'm a mech engineer though so my e&m knowledge is limited, though someone here might know definitively

>> No.6313766

>Would it be possible to use rotating magnets or some electromagnet kind of like a "magnetic sail" as propulsion eliminating the need for some sort of mass to push off of?

Yes but they're very slow. One example is an electrodynamics tether which can be used to change orbits.

>> No.6313773

>>6313767

not without doing the math. I'm not an engineer and I'm confident I could do the math. now don't be a lazy fuck and figure it out yourself. post results here.

>> No.6313777

>>6313766
Thats awesome, I was just trying to think of what would be the closest parallel to those scifi plasma engines like in district 9.

>> No.6313784

>>6313755
first, your better off just strapping an A-bomb to the ass end of your spaceship than trying to generate a controlled reaction to generate power.

second. don't fuck with the magnetosphere. i was curious about an induction drive, or even just harnessing it for power, and the only way to make it work would be to have multiple conductive rings orbiting at retarded speeds. oh, and it would kill us all.

>> No.6313801
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6313801

>>6313773
Lets figure this out together!!!
As a Team! Now >>6313744 , get with the schematics. Propose your design, then we work on it :D

>> No.6313806

> The earths magnetic field extends pretty far into space right?
it extends past the edge of the observable universe

>> No.6313823

>>6313801
For starters: F = qv x B

>> No.6313833
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6313833

Is anyone in this thread not so busy sucking dick they don't realize the absurdity of the question? The earths magnetic field extends pretty far yes but you must take into consideration that something being spread out that far will also be weaker and the size and power of the "magnetic sail" or any similar device wouldn't warrant sending it up to space in the first place.
>ITT: Hollywood's physics consultants

pic not related

>> No.6313843

>>6313833
You're right man, science is hard. Things that seem impossible should probably just never be attempted in the first place. Lets just stick to the normal way of doing things for the next 10000 years.

>> No.6313858
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6313858

>>6313833
you see poochie bear, thats why we are coming to do the math. OP is asking whether what you are asserting as fact would be the case in the event of trying to build something like this.
Now quit being a bad snugums and help us do the math :D

pic not related

>> No.6313860

>>6313843
>normal way of doing things
Well I mean if you count not attempting unreasonable feats just for the sake of "that'd be really cool" then yes I think we should continue doing that.

Science is about discovery and understand the world around us but it's not about creating things that couldn't really work. If you really want space travel and a cool new way of doing things then look at COST effective methods that aren't overly complex...
Baby steps to space.. we aren't gonna invent the warp drive without having those 10,000 years of hard work and dedication. Life isn't a science fiction movie

>> No.6313882

only issue I can think of is that since a magnetic field diminishes as 1/x^3 you're not going to be able to transmit much to a usable distance, even the strongest fields we can generate on earth still have a negligible effect after several hundred feet. You might consider reading about microwave transmission instead.

>> No.6313887

>>6313860
Your reservations on this idea are flawed though.
This type of tech is already being used for small adjustments in orbit - just type electromagnetic propulsion into google.
And yea life isn't science fiction movies of today, but a LOT of tech from scifi movies of 20-30 years ago have become a reality, so I would argue that life in fact closely follows scifi.
So maybe this idea isn't feasible today, but it could lead to other discoveries along the path. Be more optimistic my friend! :)

>> No.6313895

>>6313882
yes. You are right. But in space, you dont need an awful amount of thrust(as compared to what you'd need on the earth). So even though we might get small amounts, they just might be enough

>> No.6313909

>>6313895
assuming your generated field isn't lost in the noise of the earth's field, you'd have very little thrust, making orbital maneuvers difficult. Standard orbital mechanics assume that you can deliver your dv in a time-frame that is relatively small compared to scale at which it's operating. With a low-thrust craft such as this, you would need constant attitude control and burn along a more elongated curve which would require constant course calculation. Granted, something like that would be pretty easy to do using least-squares methods but it over-complicates the planning and leaves you with few options if you run into problems. Using electromagnetically derived propulsion systems, however, as long as you have an onboard powerplant (decay reactor in your favorite flavor), you can make plasma emission propulsion more feasible. Magnetic power transfer is horribly inefficient, but electromagnetic propulsion could be what will finally kill the chemical rocket.

>> No.6313921

>>6313744
didn't read other posts sry if i'm repeating

Smaller satellites commonly use earths magnetic field to orient themselvs