Eli5: why do rocket get launched from sea-level and not mountains

Question

Eli5: why do rocket get launched from sea-level and not mountains

In: Engineering

Answer 1

Because most of the energy spent getting a satellite into orbit is spent making fly fast enough sideways and not going straight up. The highest mountain is only 30,000 feet, roughly 6 miles; ISS is over 240 miles up. It has to go 18,000 MPH to maintain it’s orbit.

Satellites are also launched close to the sea so if there’s a catastrophic failure the rocket will be more likely to crash into the sea instead of over land.