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danielravennest t1_j6xy7x2 wrote

There's plenty of water already in space. Some nearby asteroid types contain up to 20% water and carbon compounds. The carbon compounds typically have hydrogen, and that can be combined with mineral oxides (most rocks) to make more water.

Beyond the "frost line" in the middle of the asteroid belt, water can survive in a low-g vacuum environment, so there is lots and lots of water as water and ice.

Besides, most rocket launches produce more water than they can carry as payload. They take oxygen from the air and burn it with hydrocarbons. The exhaust is CO2 and water.

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Science-Compliance t1_j6y9u19 wrote

The exhaust from a rocket is basically unusable as a source of water for astronauts. Every drop of water you take from the exhaust, too, would be reducing the rocket's efficiency. In order for that rocket to work, you need all those combustion products to fly out the back of the nozzle at high speed. Anything you put in the exhaust stream that is attached to the ship is going to reduce the effective thrust of the rocket (assuming it doesn't just melt first). You'd be better off just already having a water storage tank on the spacecraft, but then we get back to the original problem.

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danielravennest t1_j6yc2bv wrote

I was responding to the "taking water from Earth" part of the previous comment. The exhaust from a rocket launch to orbit stays in the atmosphere.

(I've done space systems engineering for 45 years now, so I do understand how rockets work).

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Science-Compliance t1_j6z398j wrote

I think it was kind of unclear how you meant that last paragraph in the context of the broader discussion, but clarification noted.

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