> Dumb question: why don't they launch rockets from the tops of mountains? Not a dumb question at all. It would actually give you some non-trivial advantage -

> Dumb question: why don't they launch rockets from the tops of mountains? Not a dumb question at all. It would actually give you some non-trivial advantage - but altitude matters considerably less than speed when trying to achieve orbit. Starting a mile higher would allow you to avoid the densest parts of atmosphere, giving you less air resistance and helping with the Max Q, or maximum dynamic pressure (rockets sometimes need to reduce their engine output until they have cleared the denser atmospheric layers, or they would break up due to air resistance stresses). This does unfortunately not outweigh the cost and complication of moving your launch site on top of a mountain. If you're really after every scrap of advantage, moving your launch site closer to the equator is way better than moving it up (until you already have it at the equator, that is).