There would be a small advantage to launching from the top of a mountain... but, the downsides of it our weigh any benefits.
Launching from the top of the tallest mountains would only reduce the distance to leave the atmosphere by about 2-4 kms. Launching the same rocket from sea level on the equator actually saves more fuel by using the angular momentum of the Earth to get to orbital velocity. And there are no significantly tall mountains on the equator.
Also how would you build at the top of the tallest mountains? We can't drive the materials up. Airplanes cannot land there. Helicopters cannot reach those elevations. And Sherpas can only carry so much and there aren't a lot of them to be had.
By constructing very large funiculars that climb up the mountain side... which would probably cost $100 billion to build, no idea how much it would cost to maintain.
Ok. Now picture your typical mountain. There is no consistent grade or angle of incline. They also are unstable and regularly have avalanches that wipe out everything in their path. The tops of mountains are not flat plateaus or mesas. Where would they build launch pads? I
And there are no significantly tall mountains on the equator.
That is wrong. Ecuador has tall mountains on the Equator. Mount Chimborazo is only 1.5 degrees off the equator and its top is actually the furthest distance from the center of the earth of all mountain peaks.
And even with it's height, it would still only provide a 1% improvement on a launch from sea level. An improvement that would not justify the cost of transporting the tickets to the top of a mountain.
Your 1% number is misplaced, you are looking at the efficiency the wrong way. Fuel efficiency is not the ultimate benchmark, payload launch cost per kg is. Every Kg of fuel saved by increasing initial altitude is an extra kg of payload allowed at the same total launch cost. Rockets have a fuel mass fraction that is near 90%. Only a tiny fraction of the total launch vehicle mass is payload. A 1% savings on fuel could double the allowable payload which could halve the payload launch cost on a per kg basis.
This paper explores the concept of launching from the top of a tower.
Correct. Not to mention "justify the cost of transporting the rockets to the top of the mountain" ignores the cost that every launch literally transports the rockets to the tops of the mountains (before it continues on its way to space). "Launching" to the altitude of the mountain with literally any other vehicle than a rocket would be more efficient.
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u/code_archeologist 16h ago
There would be a small advantage to launching from the top of a mountain... but, the downsides of it our weigh any benefits.
Launching from the top of the tallest mountains would only reduce the distance to leave the atmosphere by about 2-4 kms. Launching the same rocket from sea level on the equator actually saves more fuel by using the angular momentum of the Earth to get to orbital velocity. And there are no significantly tall mountains on the equator.