Re: Exaggerated hype
"However, the height is almost irrelevant. Only about 1% of the energy required to get into orbit is to get up to the right height; the other 99% is in the kinetic energy required to travel laterally."
So while it's true that the kinetic energy required to stay in orbit is a lot, we can work out just what fraction of the vehicle's total (gravitational Potential Energy + Kinetic Energy) is KE and how it changes with altitude. Making a few assumptions, such as the gravity in orbit being the same as on earth (it's only about 88% different at the ISS altitude, so near enough), the orbit being circular etc:
Gravitational PE = mgh, and g=GM/(h+Re)^2, Re is earth's radius, h is orbital altitude above ground.
Orbital KE=mv^2/2, where v ( for a circular orbit) =GM/(h+Re).
So, PE=GMmh/(h+Re)^2, KE=GMm/(2(h+Re))
Ratio of PE/KE = 2h/(h+Re) (after some cancelling out)
Popping some real numbers in, for the ISS at about 400km altitude, which is about the lowest orbital altitude you can do before things fall back to earth real quick due to air resistance, or keep boosting it to stay up there a la GOCE, that ratio of PE/KE is about 12%.
At a mere 100km altitude (absolutely not a viable orbital altitude for earth) that ratio becomes 3%.
The altitude at which the energy required to get there is 1% of the kinetic energy required to stay there is (for earth) about 32km above the ground.
Interestingly, the altitude at which the energy required to get there is the same as the kinetic energy required to stay there, is exactly 1 earth radius advice the surface.
I've neglected stuff like air resistance to fit through the thick air to get up there in the first place, and the KE boost you get by launching somewhere sensible like the equator and in a sensible direction, but hey!