Where does Earth’s atmosphere end and space begin? According to a new study, it might be just 50 km above the Earth, right over the place where the blue to black in this photo.
Did you feel that? Does it suddenly get a little stuffier here for you? It feels, I don’t know… the space was only 12 miles (20 km) closer?
Nothing actually moved, of course (unless you count the constant and increasing expansion of the universe). But according to a new study published online this week, it might be high time Earthlings shifted our mental and mathematical ideas about where exactly the Earth’s atmosphere ends and space begins. [Earth from Above: 101 Stunning Images from Orbit]
As astrophysicist Jonathan McDowell’s calculations are correct, the cosmic border where the laws of the skies suddenly give way to the laws of orbital space might be a lot closer than we think — a full 12 miles closer than previous estimates.
“The discussion about where the atmosphere ends and space begins pre-dates the launch of the first Sputnik,” McDowell, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics, wrotein his new paper, which appears in the October edition of the journal Acta Astronautica. “The most widely accepted limit is the so-called Karman Line, nowadays, usually set to 100 km (62 miles) altitude.”
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Here is the problem: According to McDowell, that Karman line, which many scientists accept today is based on decades of misinterpreted information, which is actually not really orbital data into account. Fortunately, data McDowell’s business (and have fun in his free time, he keeps meticulous records of every rocket launch on Earth) and he knew exactly where to look to find an evidence-based answer to the question, “Where does space begin?”
Where satellites fall
In his new study, McDowell pored over data about the orbital paths of some 43,000 satellites, which he collected from the North American Aerospace Defense Command (NORAD), which monitors the aerospace industry in the United States and Canada. Most of these satellites were negligible to McDowell, the study — they circled much higher than the proposed Karman line, and were well within the range of orbital space.
Approximately 50 of these satellites, however, was. While re-entering the atmosphere at the end of their missions, each of these satellites was successfully completed at least two full revolutions around the Earth at a height under 62 miles (100 km). The Soviet-Electron-4 satellite, for example, around the planet 10 times approximately 52 km (85 miles) before tumbling into the atmosphere and burn it in 1997.
It seemed clear from these cases that the physics of the space still held sway among the Karman line. When McDowell made use of a mathematical model for the exact point at which the different satellites finally broke loose from their jobs and made a fiery return into the atmosphere, he found that this can happen anywhere between 41 to 55 km (66 and 88 km). Usually, however, when a vessel is christened under 50 miles (80 km) mark, there was no hope of escape.
For this reason, McDowell chose 50 km as the true lower border of the space. The number of neat with a number of other cultural and atmospheric factors. For example, McDowell wrote, in the 1950’s, U. S. Air Force pilots was awarded with a special set of “astronaut wings” for flying their aircraft above 50 km, this is considered the outer edge of the atmosphere.
Attractive, the choice fits also: The mesopause — the coldest part of the atmosphere of the Earth extends roughly between 52 and 62 km above the surface of the planet. Here, in the atmosphere of the chemical composition begins to change drastically, and charged particles are more abundant. (In other words, the things look a lot spacier.) It is clear that, under the lower edge of the mesopause, the Earth atmosphere is a stronger force for airborne objects to take into account, McDowell wrote. [Infographic: Earth’s Atmosphere Top to Bottom]
“It is remarkable that meteors travel much faster) usually varies in the 70 -100 km (43 miles to 62 miles) altitude range, adding to the evidence that this is the region where the atmosphere is important,” McDowell wrote.
So, what does it mean when the border between the Earth and the space is 20 percent lower than generally assumed? It will not change the way missiles are launched, or other physical interaction with the space, McDowell wrote, but it could raise a number of important political and territorial issues.
The airspace over a particular country is generally considered to be part of that country; of the space, on the other hand, is for everyone. If the space is defined as beginning at 62 miles and the US is flying an unauthorized satellite 52 km across China, for example, that could be (rightly) regarded as an act of military aggression.
For this reason, the U.S. has often against the setting of a universal space limits. That means that McDowell proposed 50-meter line will probably not have a legal, universally accepted border anytime soon. Still, if the daily drudge of life on Earth starts getting you down, look up and take heart, that you are a little closer to heaven than you were last week.
Originally published on Live Science.