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I think you’d have to tie the spacecraft to the moon to make sure that the Earth’s gravity doesn’t keep it in place. But what do I know? I’m not a rocket scientist 🤷🏻‍♂️

Me: "Obviously silly, but I wonder if you could use the exhaust from those engines to propel the rocket upwards without using the rocket's fuel. You'd just need to focus it in a tube or something and- Oh, I'm inventing the cannon, aren't I?"

Two questions. How much impulse force would the engines need to generate to move the entire earth away from the spacecraft quickly enough that the Earth's gravity doesn't hold the craft to the surface? How reinforced would the launch pad need to be for the engines to not just punch through the earth

You just need to accelerate the Earth to escape velocity and given the direction of thrust moves 1° every 4 minutes you need to do it in under an hour because after that the change in the direction of thrust reduces the efficiency of the engines.

You also need to overcome the attractive force of the Earth so the rate of acceleration needs to exceed the 1g but not by too much otherwise everything surrounding the engines for thousands of miles will either escape Earth's gravity, possibly crash on the Moon or go into orbit.

Of course anything not tied down within 10s of miles of the launch will escape Earth's gravity. With things further and further out ending up in successively lower orbits. Luckily nobody will complain given the huge quantity of heat entering the atmosphere raising the temperature several degrees.

This makes me wonder how much thrust it would actually take to do this... alas, I don't think I'm smart enough to fugure it out, as I'm guessing it's more complicated than the other way around.

this Idea would never work. Putting the Space Craft in the middle of those 2 giant thruster the moment the space craft rises high enough it will be incinerated by the thruster exhaust I thought they're suppose to be rocket scientist 🤓

You'd need to accelerate *the entire earth* faster than it's own surface gravity would pull the capsule back down. Which would require a thrust of at least 13 million billion billion pounds. This would also cause everything else not anchored to the ground to "fall off" the earth on that side too.

And that force isnt the actual thrust you'd want out of the rocket itself, its the thrust *after accounting for earth's escape velocity* of 28,000mph that would otherwise pull the exhaust gases back to earth and lead to net zero thrust.

Yes, you'd just need 100 quintillion tons of antimatter being annihilated per second to achieve that if you used pure photons to get the most thrust per pound.

You need the relative speed between the objects to be high enough to escape gravity. Applying a constant force to an object will increase it’s speed, but inversly proportional to their mass (inertia). (Not a rocket scientist)

You could potentially create enough push from the exhaust to move the rocket, but accelerating Earth beyond escape velocity is not practically possible, by a wide margin.

Even if the engines were large enough, Earth would pull you along with it! Imagine pushing on a spherical magnet with tiny bits of metal stuck on it (similar to our being stuck via gravity); they just accelerate together. In absurd limits of acceleration, though...

If we make the acceleration the same for Earth as it would be for the rocket, I’m fairly certain we’d get roughly the same outcome. We’d need in the order of 10^18 to 10^21 times as much force, depending on the rocket, to gain the same acceleration. There is 5.5•10^14 kg of biomass. Impossible.

Sounds a bit like Futurama where, instead of moving the Planet Express ship faster than the speed of light, they "just" use the dark matter engines to move the rest of the universe in the opposite direction.