Knowledge Zone · Card 4 of 13
Orbit is falling sideways
A rocket that goes straight up comes straight back down. Height is not what keeps a ship up there — sideways speed is. An orbit is a fall that keeps missing the ground, because the ground curves away underneath at the same rate the ship drops.
That is why the whole ascent is a gravity turn: you spend your fuel buying horizontal speed, not altitude. At the game's 150 km cut-off you need roughly 7.7 km/s across the sky. Fly the Scout straight up instead and it reaches 1 700 km with its periapsis at the centre of the Earth, which is a very tall way of falling back.