Kármán line

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Layers of atmosphere. (not to scale)

The Kármán line is an imaginary boundary at an altitude of 100 km above sea level , which is used to differentiate aviation from space travel . It therefore serves as a definition for a theoretical delimitation of the earth's atmosphere from free space , which means that from around this height the atmosphere can no longer be used to generate significant dynamic lift in a flying object.

It was established by the Fédération Aéronautique Internationale (FAI) and named in honor of the aeronautical engineer Theodore von Kármán , who played a decisive role in its definition. It mainly serves to classify flight performance, as these are not comparable in the two areas below and above it. For example, it was used as a criterion for the award of the X-Prize for the first privately financed space flight.

The German A4 ("V2") with the designation MW 18014 , used in World War II , was designed as a long- range ballistic artillery missile and was the first man-made object to penetrate the Kármán line.

background

In the early 1950s, von Kármán wanted to be able to distinguish between aviation and space travel. For this he needed a definition and therefore corresponded with numerous leading scientists from these two areas. The idea behind creating a boundary was that the higher a flight object climbs, the higher the speed it needs in order to be able to fly in a controlled manner due to the aerodynamic forces. From a certain speed or height, the centrifugal force is greater than the aerodynamic forces. The air is so meaningless journey. Numerous calculations were carried out for this, which showed that the limit can be set at an altitude of around 100 kilometers. Von Kármán suggested the rounded height of 100 kilometers, which was accepted by the other scientists, and is relatively close to the calculated results.

While the FAI's interpretation is 100 km, there are other definitions. The armed forces of the United States awarded the astronaut badge from an altitude of 50 miles (about 80 km) , also set by the National Advisory Committee for Aeronautics (NACA) in the 1950s . This definition is based on the assumption that aerodynamic control of an aircraft requires a dynamic pressure on the control surfaces of at least 1 lb F / ft² (47.88  Pa ).

Under international law , none of these definitions is relevant for the delimitation of the air space subject to air sovereignty from sovereign space. The states have so far reserved the right to do so. In general, a functional delimitation has been assumed so far, depending on the activity carried out instead of the exact amount.

Web links

literature

  • Jonathan C. McDowell: The edge of space: Revisiting the Karman Line. Acta Astronautica, Volume 151, October 2018, Pages 668-677, abstract

Individual evidence

  1. ↑ Peeling Back the Layers of the Atmosphere . NOAA National Environmental Satellite, Data, and Information Service (NESDIS) February 22, 2016. Retrieved September 3, 2018.
  2. ↑ Dr. S. Sanz Fernández de Córdoba: 100km Altitude Boundary for Astronautics. Fédération Aéronautique Internationale , May 25, 2012, accessed on September 3, 2018 .
  3. ^ Space Environment and Orbital Mechanics . United States Army. Archived from the original on September 2, 2016. Retrieved September 3, 2018.