Richard Branson is an astronaut with an asterisk? A brief history of the line that delimits the boundary of space – Sidereal Messenger

With the argument between Richard Branson and Jeff Bezos about who got into space first, a new phase of discussion begins: Where is the limit of space and who actually crossed it?

This will surely be the trump card of Blue Origin’s flight with its New Shepard capsule on the next 20. The Bezos system, powered by a single-stage rocket, was designed to bypass the so-called Kármán Line, which is used by the International Astronautical . Federation was established, in the 1960s, at an altitude of 100 km.

The VSS Unity, Virgin Galactic’s spacecraft, was designed to fly a little lower and break the 80 km (50 mile) altitude used by both NASA and the US Air and Space Forces as the boundary between atmosphere and Space is accepted.

The boundary is arbitrary: in fact, there is no clear boundary between the atmosphere and the vacuum of space. What exists is a smooth transition as a spacecraft moves away from Earth, where the air becomes thinner and thinner until only a few individual molecules remain in the midst of an almost perfect vacuum. But even at about 400 km altitude, where the International Space Station (ISS) orbits, there are still some air molecules that can offer resistance and lower the orbit of the complex (which has to be pushed back up from time to time).

If there are air molecules 400 km away, they can of course also be found 80 or 100 km away. Even so, for purely legal reasons, it is important to have a clear definition of what separates air from space. Different international rules apply to the aerospace industry. Take the airspace situation, for example. Flying over a country by air requires a special permit from the local government, while a satellite flying over a country does not require a permit; the space is treated as “international water” to draw a maritime example and complete the rift.

It was up to the Hungarian-American engineer and physicist Theodore von Kármán (1881-1963) to emphasize the importance of this definition and to make calculations to support the arbitrary dividing line. And the criterion chosen was sensible: the atmosphere ends where the air is so thin that no significant aerodynamic lift can be generated. In short, this is where the aircraft’s wings lose their function.

Interestingly, Kármán’s initial calculation was closer to the current American definition: 84 km. But the nice round number of 100 km (which doesn’t look very nice and round in miles, imperial unit used in the USA: 62.5) was adopted internationally by the FAI, with the support of the Americans and the Soviets. In fact, NASA adopted the 100 km Kármán line as its own standard by 2005 Special Place: Civilian and military pilots using the same vehicle (in this case the X-15 rocket) may or may not be considered astronauts, depending after who answered.

Precisely for this reason, Jeff Bezos’ Blue Origin now cites as one of the arguments for his vehicle that anyone who flies with it receives astronaut status according to one of the existing criteria without having an asterisk next to the name to explain aloud who they actually flew into space.

Like the old asterisk for US civil and military pilots, however, this is also tending to decline. Since 2019 there have been movements and discussions at the FAI to “downgrade” the Kármán line to 80 km. The arguments range from technical (Kármán’s original calculations and the fact that satellites survive multiple orbits in space on orbits with a perigee between 80 and 90 km) to historical and cultural (the fact that one of the countries with the longest tradition of Spacecraft uses it and that there are currently “star astronauts.” The technical advantage between Blue Origin and Virgin Galactic is unlikely to last long. Experience has shown that the difference is even smaller – so much so that Jeff Bezos’ company also makes other arguments such as minor Cites environmental pollution, security features and much larger windows to justify the superiority of his system. The asterisk is just that: an asterisk.

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