Escape Velocity

[Bhodi Li]

As it's been discussed in another thread, escape velocity on Earth is going straight up at about 25,000 MPH but that's at sea level. The higher you get the less speed you need to escape the Earth's gravity well, assuming you're going in the direction of straight up (that's what velocity is, speed and direction.) For instance, the escape velocity at the top of Mount Everest is less than what it is at sea level.

Now I know it wouldn't be practical to build a launch pad on top of Mount Everest, but if we could build launch pads at higher altitudes, if we built tall enough structures that we could put the launch pads on top of, we would need less energy and therefore less fuel to put spacecraft into orbit or to completely leave Earth.

 

[Classical Motion]

Large balloons could go much higher than Everest. And could be recycled.

A balloon for the first short booster.

 

[Bhodi Li]

Large balloons could go much higher than Everest. And could be recycled.

A balloon for the first short booster.

You would need a really big balloon to lift a spacecraft.

 

[Hevach]

Excepting things like direct ascent lunar/deep space launches (which aren't really the norm) most of the velocity you need to stay in space is horizontal, not vertical. Modern rockets start pitching over towards horizontal basically as soon as they clear the ground structures.

There is still an altitude advantage here. We launch vertical to get out of the soup of the thickest atmosphere, and if we can get a few thousand feed of that atmosphere behind us without riding an explosion we can get to the important horizontal flight faster.