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by thehappypm 743 days ago
No atmosphere would be much easier.

There's enough energy in a Tesla battery to for the Tesla to reach escape velocity. If you could simply drive at max acceleration (and the car didn't fall apart, and the tires continued to have grip, and a million other reasons why this is impossible) eventually you'd reach escape velocity and still have some percentage left.

In a more realistic sense, a long railgun type system would be very practical in a no-atmosphere environment, and then not being subject to the tyranny of the rocket equation, you could launch whatever you wanted. Enough fuel to decelerate is no problem.
3 comments
Denvercoder9 743 days ago
> There's enough energy in a Tesla battery to for the Tesla to reach escape velocity.

No, it's not even remotely close. A Model S weighs around 2000kg and has a battery of 100 kWh. That's √((100 kWh)/(1/2*2000kg)) = 600m/s of delta-v. Escape velocity for Earth is 11.2km/s, almost a factor 20 more.

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thehappypm 742 days ago
My math was off!

This nerd sniped me a LOT, I’m wondering if it’s possible for a chemical battery to reach orbital velocity (not escape).

An idealized Tesla would just be its battery (500kg) perfectly dumping energy to mechanical forward speed. Cutting 3/4 of the weight gets you closer to the delta-v you need, but youre still off by a factor of 5. Though orbital velocity, and leaving from the equator and gaining that speed, means you only need to get up to ~7.2 km/s. Still only a third of the way there.

Maybe you could split your battery into chunks, and expel them once they’re expended?

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PaulHoule 743 days ago
Seems challenging to get decelerated by a rail gun, coil gun or such at the destination. You get one chance to get caught by it otherwise you crash and die.
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thehappypm 742 days ago
Use a giant spring! When you land, aim for the spring, and charge it for the next launch!
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jccooper 743 days ago
An airless Earth would be extremely hard to land on. You could easily get to quite low altitude, but orbital velocity at sea level is almost 8km/2... faster than at "orbital altitude".

Once you hit an orbit intersecting the ground, you have to scrub all your speed in whatever that amount of time is, which is gonna be short. It's basically an orbital launch in reverse.

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