McDowell line
English[edit]
Alternative forms[edit]
Etymology[edit]
(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.
Noun[edit]
- (aerospace) The altitude of periapsis at which atmospheric drag will prevent an object from successfully orbiting.
Usage notes[edit]
(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.