Editing 1375: Astronaut Vandalism
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The title text references the fact that while the {{W|Fédération Aéronautique Internationale}} (FAI) defines the {{W|Kármán line}}, the boundary between {{W|Earth's atmosphere}} and {{W|outer space}} (i.e., the start of space), to be 100 kilometers (62 miles) above mean sea level, the {{W|U.S. Air Force}} and other military branches will award {{W|astronaut wings}} to rated astronauts who fly higher than 50 miles (80 km). In 2005 {{W|NASA}} changed from using the FAI definition to using the USAF definition for consistency across organizations, and thus some NASA test pilots who had flown the {{w|X-15}} retroactively received astronaut wings for their greater-than-50 mi (80.5 kilometers) flights. (Air Force pilots of the X-15 in the 1960s had long since received astronaut wings for such flights.) Thus in the title text, Air Force pilots surreptitiously change the sign to conform to their definition of "space". | The title text references the fact that while the {{W|Fédération Aéronautique Internationale}} (FAI) defines the {{W|Kármán line}}, the boundary between {{W|Earth's atmosphere}} and {{W|outer space}} (i.e., the start of space), to be 100 kilometers (62 miles) above mean sea level, the {{W|U.S. Air Force}} and other military branches will award {{W|astronaut wings}} to rated astronauts who fly higher than 50 miles (80 km). In 2005 {{W|NASA}} changed from using the FAI definition to using the USAF definition for consistency across organizations, and thus some NASA test pilots who had flown the {{w|X-15}} retroactively received astronaut wings for their greater-than-50 mi (80.5 kilometers) flights. (Air Force pilots of the X-15 in the 1960s had long since received astronaut wings for such flights.) Thus in the title text, Air Force pilots surreptitiously change the sign to conform to their definition of "space". | ||
| − | Although most authorities use the FAI definition of space - the Kármán line - since the FAI is the international organization of record for aeronautics, there are good scientific reasons for the U.S. Air Force definition. The line is named for {{W|Theodore von Kármán}}, who originally calculated the height at which | + | Although most authorities use the FAI definition of space - the Kármán line - since the FAI is the international organization of record for aeronautics, there are good scientific reasons for the U.S. Air Force definition. The line is named for {{W|Theodore von Kármán}}, who originally calculated the height at which an vehicle would have to travel faster than orbital velocity to generate lift from wings, therefore making the vehicle an object in orbit rather one using air to generate lift. Von Kármán originally calculated this height as 51.9 miles (83.6 km) - closer to the USAF definition than to what is now called the Kármán line. Additionally, the boundary between the {{W|mesosphere}} and the {{W|thermosphere}} is traditionally taken to be 53 miles (85 km), also close to the Air Force definition. On the other hand, some newer research suggests the {{W|mesopause}} (the line between the mesosphere and thermosphere) may have peaks between 53 and 62 miles (85-100 km). Also the {{W|turbopause}} - the line where gas molecules cease mixing atmospherically and begin stratifying by molecular weight as if they are in orbit - is generally taken to be about 100 kilometers (62 miles). |
All of the atmospheric boundaries are variable, however, changing from day to day and season to season with no clear boundary. Additionally, objects cannot reliably orbit below 130-150 km (80-93 miles) due to drag from even the sparse atmosphere in the lower thermosphere. Despite this comic associating "space" with having a definite start the way you might definitely know when you cross the city limits of a town, the reality is that the transition from atmosphere to space takes place gradually over tens of kilometers. Interestingly, since it is too high for aircraft and high altitude balloons, but too low for spacecraft in orbit, this "near space" transition region is one of the least-visited and least-used regions of the larger atmosphere. This comic thus both points out that the limit where space starts is arbitrarily chosen and also that space is often much closer than, for instance, two nearby cities in some randomly chosen location in the US. | All of the atmospheric boundaries are variable, however, changing from day to day and season to season with no clear boundary. Additionally, objects cannot reliably orbit below 130-150 km (80-93 miles) due to drag from even the sparse atmosphere in the lower thermosphere. Despite this comic associating "space" with having a definite start the way you might definitely know when you cross the city limits of a town, the reality is that the transition from atmosphere to space takes place gradually over tens of kilometers. Interestingly, since it is too high for aircraft and high altitude balloons, but too low for spacecraft in orbit, this "near space" transition region is one of the least-visited and least-used regions of the larger atmosphere. This comic thus both points out that the limit where space starts is arbitrarily chosen and also that space is often much closer than, for instance, two nearby cities in some randomly chosen location in the US. | ||
