Kármán line

edge of spaceKarman linethe United States definitionboundary of spacespaceedge of outer space100 km100km altitude50 miles in altitude62-mile height
The Kármán line is an attempt to define a boundary between Earth's atmosphere and outer space.wikipedia
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Outer space

spaceinterstellar spaceintergalactic medium
The Kármán line is an attempt to define a boundary between Earth's atmosphere and outer space.
However, the Kármán line, an altitude of 100 km above sea level, is conventionally used as the start of outer space in space treaties and for aerospace records keeping.

Altitude

high altitudealtitudeshigh-altitude
The Fédération Aéronautique Internationale (FAI; English: World Air Sports Federation), an international standard-setting and record-keeping body for aeronautics and astronautics, defines the Kármán line as the altitude of 100 km above Earth's mean sea level.
The Kármán line, at an altitude of 100 km above sea level, by convention defines represents the demarcation between the atmosphere and space.

Thermosphere

as high as 180 –Earth's thermospherehigh altitudes
The mesopause atmospheric temperature minimum has been measured to vary from 85 to 100 km, which places the line at or near the bottom of the thermosphere. The U.S. Air Force definition of an astronaut is a person who has flown higher than 50 mi above mean sea level, approximately the line between the mesosphere and the thermosphere.
In the exosphere, beginning at about 600 km (375 mi) above sea level, the atmosphere turns into space, although by the judicial criteria set for the definition of the Kármán line, the thermosphere itself is part of space.

Earth

Earth's surfaceterrestrialworld
The Fédération Aéronautique Internationale (FAI; English: World Air Sports Federation), an international standard-setting and record-keeping body for aeronautics and astronautics, defines the Kármán line as the altitude of 100 km above Earth's mean sea level.
The Kármán line, defined as 100 km above Earth's surface, is a working definition for the boundary between the atmosphere and outer space.

Theodore von Kármán

Theodore von Karmanvon Kármánvon Karman
The line is named after Theodore von Kármán (1881–1963), a Hungarian American engineer and physicist, who was active primarily in aeronautics and astronautics.

Astronaut

cosmonautastronautscosmonauts
The U.S. Air Force definition of an astronaut is a person who has flown higher than 50 mi above mean sea level, approximately the line between the mesosphere and the thermosphere.
The Fédération Aéronautique Internationale (FAI) Sporting Code for astronautics recognizes only flights that exceed the Kármán line, at an altitude of 100 km.

North American X-15

X-15North American X-15A-2X-15 rocket plane
NASA formerly used the FAI's 100 km figure, though this was changed in 2005, to eliminate any inconsistency between military personnel and civilians flying in the same vehicle, when three veteran NASA X-15 pilots (John B. McKay, William H. Dana and Joseph Albert Walker) were retroactively (two posthumously) awarded their astronaut wings, as they had flown between 90 km and 108 km in the 1960s, but at the time had not been recognized as astronauts.
The X-15 set speed and altitude records in the 1960s, reaching the edge of outer space and returning with valuable data used in aircraft and spacecraft design.

Joseph A. Walker

Joe WalkerJoseph Albert WalkerJoseph Walker
NASA formerly used the FAI's 100 km figure, though this was changed in 2005, to eliminate any inconsistency between military personnel and civilians flying in the same vehicle, when three veteran NASA X-15 pilots (John B. McKay, William H. Dana and Joseph Albert Walker) were retroactively (two posthumously) awarded their astronaut wings, as they had flown between 90 km and 108 km in the 1960s, but at the time had not been recognized as astronauts.
In 1963 Walker made three flights above 50 miles, thereby qualifying as an astronaut according to the United States definition of the boundary of space.

Mesosphere

upper atmospherenear spacemesospheric
The U.S. Air Force definition of an astronaut is a person who has flown higher than 50 mi above mean sea level, approximately the line between the mesosphere and the thermosphere.
This term does not have a technical definition, but typically refers to the region of the atmosphere up to 100 km, roughly between the Armstrong limit (above which humans require a pressure suit in order to survive) and the Kármán line (where astrodynamics must take over from aerodynamics in order to achieve flight); or, by another definition, to the range of altitudes below which commercial airliners fly but above which satellites orbit the Earth.

William H. Dana

Bill DanaWilliam H. "Bill" DanaWilliam "Bill" Dana
NASA formerly used the FAI's 100 km figure, though this was changed in 2005, to eliminate any inconsistency between military personnel and civilians flying in the same vehicle, when three veteran NASA X-15 pilots (John B. McKay, William H. Dana and Joseph Albert Walker) were retroactively (two posthumously) awarded their astronaut wings, as they had flown between 90 km and 108 km in the 1960s, but at the time had not been recognized as astronauts.
On two separate flights, Dana flew the X-15 to an altitude above 50 miles, thereby qualifying as an astronaut according to the United States definition of the boundary of space; however neither flight exceeded the Kármán line, the internationally accepted boundary of 100 kilometers (62 miles).

John B. McKay

John McKayJohn B. "Jack" McKay
NASA formerly used the FAI's 100 km figure, though this was changed in 2005, to eliminate any inconsistency between military personnel and civilians flying in the same vehicle, when three veteran NASA X-15 pilots (John B. McKay, William H. Dana and Joseph Albert Walker) were retroactively (two posthumously) awarded their astronaut wings, as they had flown between 90 km and 108 km in the 1960s, but at the time had not been recognized as astronauts.
On September 28, 1965, he flew the X-15 to an altitude above 50 miles, thereby qualifying as an astronaut according to the United States definition of the boundary of space.

Airspace

air spaceinternational airspacenational airspace
They include the physical constitution of the air; the biological and physiological viability; and still other factors which logically join to establish a point at which air no longer exists and at which airspace ends.
The Fédération Aéronautique Internationale has established the Kármán line—at an altitude of 100 km—as the boundary between the Earth's atmosphere and outer space, while the United States considers anyone who has flown above 80 km to be an astronaut.

Atmosphere of Earth

airEarth's atmosphereatmosphere
The Kármán line is an attempt to define a boundary between Earth's atmosphere and outer space. They include the physical constitution of the air; the biological and physiological viability; and still other factors which logically join to establish a point at which air no longer exists and at which airspace ends.
The Kármán line, at 100 km, or 1.57% of Earth's radius, is often used as the border between the atmosphere and outer space.

V-2 rocket

V-2V2V2 rocket
The V-2 rocket also became the first man-made object to travel into space by crossing the Kármán line with the vertical launch of MW 18014 on 20 June 1944.

MW 18014

a V-2 test rocket
It was the first man-made object to reach outer space, attaining an apogee of 176 kilometers, which is above the Kármán line.

Jonathan McDowell

Recent works by Jonathan McDowell (Harvard-Smithsonian Center for Astrophysics) and Thomas Gangale (University of Nebraska-Lincoln) advocate that the demarcation of space should be at 80 km, citing as evidence von Kármán's original notes and calculations (which concluded the boundary should be 270,000 ft), plus functional, cultural, physical, technological, mathematical, and historical factors.
It also differs from the internationally accepted Kármán line altitude of 100 km, used by the Fédération Aéronautique Internationale for the same purpose.

United States Astronaut Badge

astronaut wingsAstronaut BadgeNavy Astronaut Wings
NASA formerly used the FAI's 100 km figure, though this was changed in 2005, to eliminate any inconsistency between military personnel and civilians flying in the same vehicle, when three veteran NASA X-15 pilots (John B. McKay, William H. Dana and Joseph Albert Walker) were retroactively (two posthumously) awarded their astronaut wings, as they had flown between 90 km and 108 km in the 1960s, but at the time had not been recognized as astronauts.

Fédération Aéronautique Internationale

FAIFederation Aeronautique InternationaleInternational Aeronautical Federation
The Fédération Aéronautique Internationale (FAI; English: World Air Sports Federation), an international standard-setting and record-keeping body for aeronautics and astronautics, defines the Kármán line as the altitude of 100 km above Earth's mean sea level.

Aeronautics

aeronauticalaeronautaeronautic
The Fédération Aéronautique Internationale (FAI; English: World Air Sports Federation), an international standard-setting and record-keeping body for aeronautics and astronautics, defines the Kármán line as the altitude of 100 km above Earth's mean sea level. The line is named after Theodore von Kármán (1881–1963), a Hungarian American engineer and physicist, who was active primarily in aeronautics and astronautics.

Astronautics

cosmonauticsAstronautical Engineeringastronautical
The Fédération Aéronautique Internationale (FAI; English: World Air Sports Federation), an international standard-setting and record-keeping body for aeronautics and astronautics, defines the Kármán line as the altitude of 100 km above Earth's mean sea level. The line is named after Theodore von Kármán (1881–1963), a Hungarian American engineer and physicist, who was active primarily in aeronautics and astronautics.

Metres above sea level

above sea levelAMSLabove mean sea level
The Fédération Aéronautique Internationale (FAI; English: World Air Sports Federation), an international standard-setting and record-keeping body for aeronautics and astronautics, defines the Kármán line as the altitude of 100 km above Earth's mean sea level. The U.S. Air Force definition of an astronaut is a person who has flown higher than 50 mi above mean sea level, approximately the line between the mesosphere and the thermosphere.

NASA

National Aeronautics and Space AdministrationNASA Advisory CouncilU.S. space program
NASA formerly used the FAI's 100 km figure, though this was changed in 2005, to eliminate any inconsistency between military personnel and civilians flying in the same vehicle, when three veteran NASA X-15 pilots (John B. McKay, William H. Dana and Joseph Albert Walker) were retroactively (two posthumously) awarded their astronaut wings, as they had flown between 90 km and 108 km in the 1960s, but at the time had not been recognized as astronauts. For instance, the US Air Force and NASA define the limit to be 50 miles above sea level.

Hungarian Americans

Hungarian-AmericanHungarian AmericanHungarian
The line is named after Theodore von Kármán (1881–1963), a Hungarian American engineer and physicist, who was active primarily in aeronautics and astronautics.

Engineer

engineersconsulting engineerIr.
The line is named after Theodore von Kármán (1881–1963), a Hungarian American engineer and physicist, who was active primarily in aeronautics and astronautics.

Physicist

physicistsresearch physicistengineer and physicist
The line is named after Theodore von Kármán (1881–1963), a Hungarian American engineer and physicist, who was active primarily in aeronautics and astronautics.