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A rocket does not push against the air. It works better where there is no air to push on.

Physics Facts, sourced to NASA Glenn Research Center.

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A newspaper editorial once mocked Robert Goddard for suggesting otherwise. The engine throws mass out of the nozzle at high speed, and the reaction to throwing it is the thrust; nothing outside the vehicle is involved. Air only gets in the way, both as drag and as back pressure on the nozzle, so the same engine produces more thrust in vacuum than at sea level. The paper printed a correction the week of the first moon landing.

The claim comes from NASA Glenn Research Center.

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