I was wondering what would happen if you attach 2 Huge ion engines(I mean really really really huge) to planet earth.

They should be attached on the north and south poles.

Are 2 huge ion engines able to fly planet earth out of our solar system into space? And how much power does this need to happen?

If planet earth ends up in space what would happen to it? Would it burst out in flames cause of the speed or end up being a huge ball of ice because of the cold space and all the water on earth?

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    $\begingroup$ My guess would be that the re-entry of toxic chemicals that would be released by these jet engines would kills us off long before we would begin to see any orbital effects. $\endgroup$ – Neil Jan 16 '15 at 13:12
  • $\begingroup$ But what would happen to planet earth? After it launches into space? $\endgroup$ – Stefan Jan 16 '15 at 13:13
  • $\begingroup$ There seems to be several questions here, asking each question separately would increase the likelihood of high-quality answers. $\endgroup$ – Scott Downey Jan 16 '15 at 13:13
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    $\begingroup$ Planet earth is in space. If it ends up further away from the sun, it'll get colder, but there's no way jet engines can do that (you really need to specify how huge you're thinking of). $\endgroup$ – RemcoGerlich Jan 16 '15 at 13:13
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    $\begingroup$ You should take your question about the force required to move the Earth out of our Solar system to the Space StackExchange. Then consider rewording your question to ask about the specific impact areas you want to know about: climate, civilization, tidal forces, etc. Note that the energy levels involved in moving celestial objects would require a Type II civilization on the Kardashev scale. $\endgroup$ – Lilienthal Jan 16 '15 at 18:14

The problem with ion engines is that while they do not need lots of propellant they consume ridiculous amounts of energy to do so. This is because the energy goes up with the square of exhaust velocity while the impulse goes up linearly and ion drives have very high exhaust velocities. Worse the delta-v is proportional to the logarithm of the ratio of starting and ending masses of what you want to accelerate. Since the whole point of switching to ion engined was to avoid using large amounts of the planet as propellant that ratio will be very close to 1. The logarithm of 1 is 0, meaning you will not get anything done, other than consume ridiculous amounts of energy. I'd guess that the only result will be that the polar ice caps will melt?

This is a general rule of how propulsion works. You can either spend significant amounts of your starting mass as propellant, which in this case would make the planet uninhabitable, or you can spend lots of energy without getting much of anything done.

The question previously specified jet engines, leaving it here.

Jet engines work by sucking in air and propelling it. So your engines would suck in our atmosphere and propel it into outer space. Eventually the low pressure would convert all of our water into gas and expel it as well. At that point you'd have a barren planet devoid of air, water, and life still at pretty much (but not quite) the same orbit as it was before. There is not enough air and water to make a difference, unless we assume some sort of super-science engine capable of propelling gas into relativistic velocities.

And if you assume super-science you might as well assume an engine that can move planets without making them inhabitable. Any kind of reactionless or FTL drive could be scaled to planet size.

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    $\begingroup$ Which is why you should use ion engines. $\endgroup$ – Braiam Jan 16 '15 at 13:53
  • $\begingroup$ Allright gonna change my question to ion engines! Thanks :-) $\endgroup$ – Stefan Jan 16 '15 at 14:23
  • $\begingroup$ I assume you mean without making them uninhabitable, no? $\endgroup$ – cpast Jan 16 '15 at 18:45
  • $\begingroup$ @Stefan: You shouldn't have done that as it entirely changes the question. Please revert and then post a new one! $\endgroup$ – Lightness Races in Orbit Jan 16 '15 at 18:57
  • $\begingroup$ If you limit the amount of reaction mass to the entire atmosphere then the specific impulse you need is about $120c$. Using all the oceans too, you get a figure of $0.4c$: within the theoretical reach of a rocket powered by total antimatter annihilation of the reaction mass. $\endgroup$ – 2012rcampion Jan 18 '15 at 6:37

Nothing. They would push against the atmosphere, the air in the atmosphere would circulate a bit, but eventually it would cancel out any net force.

So lets assume you suck the atmosphere away...

First, we all die. Then...

Assuming they were equal power engines, if you pointed both engines "up" nothing. They would cancel each other out.

If you pointed them parallel to the ground, mostly nothing. The earth spins. The engines would cancel themselves out over the course of a 24 hour period.

If you pointed them parallel to the ground, on rotating discs so they were always pointing "prograde" (ie. in the direction of earth's orbit around the sun) then they would slowly enlarge the orbit around the sun. Of course it's so slow, you'll die before you could measure a difference.


First and foremost, Earth IS in space, it just happens to be orbiting close to a big burning ball of gas.

Second, putting them on the north and south pole, they would rotate with the planet and mostly cancel themselves out. Unless of course the were facing opposite directions, then they might start to give the earth a north-south spin, which with our daily rotation would put the planet in a terrible wobble.

This of course ignores the problems of actually mounting the engines on the planet, since the north pole is a floating Ice cap and also of the huge fuel consumption needed to make any change in the momentum of the earths mass.

Oh and if you got it out of the solar system, quite likely it would turn into a big ball of ice. Though the engines might produce enough heat for survival nearby.


To get the effect you desire here, you will need a way beyond our technology to do so. The problem with existing propulsion is it ultimately depends on Newton and his every force has and equal and opposite force. Flight on earth works because you have the air to push against...you send air in one direction and the equal amount of energy of that air going in one direction is applied to you as force in the other direction.

The issue here is very much the mass of earth. The entire atmosphere of earth is approximately 1 millionth the mass of earth...meaning if you took the entire atmosphere of earth and shot it into space you would get an amount of force equal to F=MA (force equals mass times acceleration) applied to earth in the opposite direction. This works to acceleration of our atmosphere ejected into space / 10000000 = acceleration of earth. I guess if you manage to send our entire atmosphere off into space at 1% the speed of light you might speed us up by a couple meters per second? compared to the 30'000 m/s Earth is currently moving around the sun, it's not much of a change. Water makes up 0.2% of the earths mass...ejecting our entire ocean into space at a few hundred thousand meters per second in the same direction might have the chance of slightly changing our orbit? Leaves jet engine...even Ion engine...as not very likely to succeed here regardless of size.

To achieve something like this, we would require the ability to effect mass and gravity (I think thats the Kardashev-scale II Lilienthal mentions). If we find a method of creating a gravity well (black hole style) in the direction you want to move, the earth and this blackhole would be attracted to each other and we would begin moving towards it. When we get close, collapsing the blackhole, regaining the energy, and recreating it again in the direction we want...rinse and repeat...then we could start moving the planet. I've got a few other versions of this, but they are as psuedo-theoretical as star trek warp drive is.


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