McDowell, who is well known in the space community for his research on this topic, has argued that the Kármán line is not based in scientific reasoning. According to his analyses of historical data, Virgin Galactic is right—space begins about 50 miles (80 kilometers) from the ground.
Neither Blue Origin nor Virgin Galactic can put people into orbit around Earth, but the nature of orbits provides a useful way to understand this problem. Imagine you’re a satellite traveling in an elongated orbit around Earth, and your closest approach brings you less than 50 or so miles from the ground. At that point, the atmosphere will assert its presence and drag you down into a fiery plunge. But if your approach takes you above 50 miles, “you will likely survive ’til the next orbit and go around,” McDowell said. At this boundary—which I’m calling the McDowell line—gravitational forces become more important than atmospheric ones.
There are a variety of reasons McDowell argues that 80 kilometers is the clearest boundary of space, such as the scientific measure of the Earth’s atmosphere, the gravitational physics, and the historical precedent — including that Hungarian-American engineer Theodore von Kármán’s original line was closer to 80 than 100.
Picture Credit : Google
