Editing 1375: Astronaut Vandalism
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==Explanation== | ==Explanation== | ||
− | Signs like this normally show the distance to places on earth's surface. This sign also has an arrow pointing away from earth and towards "space", with a distance of 62 miles (100 km), due to "astronaut vandalism". | + | Signs like this normally show the distance to places on earth's surface. This sign also has an arrow pointing away from earth and towards "space", with a distance of 62 miles (100 km), due to "astronaut vandalism". 62 miles being the {{w|Kármán line}}, the lowest of the conventional borders to demarcate the beginning of "{{w|outer space}}". |
− | We think of | + | We think of Space as being so very far away. This comic puts into perspective that it's really a lot closer to get to Space than to many destinations we're used to getting to by car or airplane. We think of 62 miles as being an easy trip on the ground, but that same 62 miles is incredibly hard when going vertically, against the force of gravity. Distance-wise, however, it's the same. |
− | 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 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|USAF}} 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 U.S. Air Force definition for consistency across organizations, and thus some NASA test pilots in retroactively received astronaut wings by the for their greater-than-50 mi (80.5 kilometers) flights on the {{w|X-15}} (Air Force pilots of the X-15 had received astronaut wings for such flights in the 1960s). Thus the Air Force pilots wanting to change the sign and validate the Air Force's award of astronaut wings by making space "closer". |
− | Although most authorities use the FAI definition of | + | Although most authorities use the FAI definition of the Kármán line since it 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 an "air"craft using air to keep it up). Von Kármán originally calculated this height as 51.9 miles (83.6 km) - closer to the Air Force definition. Additionally, the boundary between the {{W|Mesosphere}} and the {{W|Thermosphere}} is traditionally taken to be 52.7 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 52.7 miles 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 | + | 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 or 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 the two largest cities in some randomly chosen location in the US. One possible location is Grenada, MS, which is about 100 miles from Memphis, TN and about 114 miles from Jackson, MS. Conversely it could mean Jackson, TN in which case Tupelo, MS or Kenneth, MO are both viable cities where the post is located, except in Tupelo, MS the roads to Jackson and Memphis meet in a right angle, instead of being in opposite directions like the comic. | |
==Transcript== | ==Transcript== |