A spacecraft that takes off on a runway, with rocket engines that do not require external oxygen, seems like a safer approach to get off the ground than being strapped to a controlled explosion.
In: Physics
It’s because the private space flights abuse the arbitrary altitude of “space” that was set to 100km.
Other spaceships go there to do something useful, not just for the sake of going. They need to get to orbital speed and altitude. ISS is at the altitude of 400+km, which is considered low Earth orbit that’s 4 time higher. It also moves at over 7km/s, much, much faster than the Virgin craft.
So, technically, they are in space. But it’s just a short hop to that arbitrary altitude, so it requires only fraction of energy compared to a useful rocket.
For comparison, even ICBMs, the rockets that can carry nuclear weapons, get to higher altitude before they fall on their target.
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