McDowell line

English

Etymology

(aerospace): From being proposed by astrophysicist Jonathan C. McDowell in 2018; when analyzing orbiting satellites to determine the perigee altitude at which one can successfully orbit 2 or more times on a highly elliptical orbit.

Alternative forms

McDowell Line, McDowell Limit, McDowell limit

Noun

McDowell line (plural unknown or uncertain)

(aerospace) The altitude of periapsis at which atmospheric drag will prevent an object from successfully orbiting.

Usage notes

(aerospace): This is treated as the border between the Earth's atmosphere and outer space. It is defined as a static altitude of 80km (50 mi) above sea level (ASL) on Earth; the U.S. government (NASA, USAF, FAA) has used the limit of 50 mi (80km) ASL prior to its definition by McDowell, under its interpretation of the Kármán line. The Karman line is frequently treated as a static altitude of 100km ASL, by many, as the border with space. The actual altitude of the McDowell line is dynamic and not static, and depends on atmospheric conditions. Where both the 100km and 80km limits are used at the same time, the 100km limit is the Karman line and the 80km line is the McDowell line.

Coordinate terms

aerospace

Karman limit
Kármán limit
Karman line
Kármán line

单词	McDowell line
释义	McDowell line English Etymology (aerospace): From being proposed by astrophysicist Jonathan C. McDowell in 2018; when analyzing orbiting satellites to determine the perigee altitude at which one can successfully orbit 2 or more times on a highly elliptical orbit. Alternative forms McDowell Line, McDowell Limit, McDowell limit Noun McDowell line (plural unknown or uncertain) (aerospace) The altitude of periapsis at which atmospheric drag will prevent an object from successfully orbiting. Usage notes (aerospace): This is treated as the border between the Earth's atmosphere and outer space. It is defined as a static altitude of 80km (50 mi) above sea level (ASL) on Earth; the U.S. government (NASA, USAF, FAA) has used the limit of 50 mi (80km) ASL prior to its definition by McDowell, under its interpretation of the Kármán line. The Karman line is frequently treated as a static altitude of 100km ASL, by many, as the border with space. The actual altitude of the McDowell line is dynamic and not static, and depends on atmospheric conditions. Where both the 100km and 80km limits are used at the same time, the 100km limit is the Karman line and the 80km line is the McDowell line. Coordinate terms aerospace Karman limit Kármán limit Karman line Kármán line See also aerospace Armstrong line death zone mesopause
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