posted 05-21-2004 08:03 PM               

If I remember correctly the U.S. Air Force awards astronaut wings to people who fly over 50 miles high.

posted 05-21-2004 08:41 PM               

Strategically, the U.S. has never defined an altitude for space so as not to set a limit where its (restricted) airspace ends. (To that end Eisenhower was briefed by Asst. Secretary of Defense Donald Quarles that the Russians had done the United States a "good turn" by launching Sputnik, thus "establishing the concept of freedom of space." [Source: "Sputnik: The Shock Of The Century" by Dickson]).

The U.S. Air Force did award astronaut wings for flights above 50 miles, however this was arguably in response to NASA having already declared one of its sub-orbital pilots (Shepard) as having reached space.

posted 05-21-2004 11:41 PM               

quote:

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Originally posted by Robert Pearlman:
The world air sports federation, the Federation Aeronautique Internationale (FAI) set 100 km (62 miles)...

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posted 07-29-2004 04:10 PM               

Where does 'space' begin?

By Louise Thorn, Astronomy Education Assistant, National Air and Space Museum

When humankind first began going into space, there was no worldwide consensus as to what "space" was, and surprisingly, there still isn't. The need for an official definition became apparent with the launch of Earth's first artificial satellite, Sputnik, on October 4, 1957, which traveled around Earth at altitudes between 227 kilometers (142 miles) at the closest point and 945 kilometers (591 miles) at the farthest.

In the 1960s, the X-15 space plane missions gave us the first glimpses of human space travel. The pioneering X-15 pilots were awarded "astronaut wings" whenever they exceeded the threshold of 80 kilometers (50 miles) altitude, the definition of "space" as deemed by the U.S. Air Force.

However, the Federation Aeronautique Internationale (FAI), the recognized world authority for aeronautical records, declared that aircraft would have to exceed 100 kilometers (62.5 miles) in order for the pilot to qualify for astronaut status. To win the X Prize, competitors must reach the 100 kilometer altitude.

Why 100 kilometers? Because for an aircraft, flying above this altitude is impossible, since lift is no longer effective in the thinning atmosphere. And a spacecraft moving below this altitude would encounter increasing drag, thus reducing its circular orbital speed and causing it to spiral toward Earth. Tests with a Soviet low-altitude satellite in the 1960s confirmed this theory by completing a few orbits above 100 kilometers before rapidly tumbling to earth as it dipped below the 100 kilometer threshold.

This 100 kilometer boundary is known as the Karman Line, having been proposed by Hungarian scientist Theodore Von Karman. Simply put, it denotes where aeronautics becomes astronautics, aeronautics being flight that requires atmosphere, and astronautics being flight that does not require atmosphere. Although 100 kilometers sounds suspiciously convenient, the Karman line can actually be scientifically measured as a definite change.

As the Space Race between the United States and the Soviet Union intensified, the United Nations decided to create an Office for Outer Space Affairs to add legal definition to space activities. Intriguingly, the 1967 Outer Space Treaty itself does not include a definition of where outer space begins, so we can find no clues here.

The only legal document containing a definition of space is the Australian Space Activities Act of 1998 which requires all objects launched from the continent to an altitude greater than 100 kilometers be licensed. Although major space agencies such as the National Aeronautics and Space Administration and the European Space Agency use the general consensus of 100 kilometers, there is still no legally binding stipulation to accept this value. Other definitions of space include: in medicine, the point at which humans must have life-support systems to survive is 24 kilometers/15 miles; in propulsion, the distance where a propulsion system needs to provide its own oxygen as well as fuel is 45 kilometers/28 miles; and the 'atmospheric interface' encountered by the Space Shuttle orbiter on re-entry is at a distance of 122 kilometers/76 miles.

So, to answer our question, "Where does space begin?" we can only reply, "Depends on who you ask!"

posted 07-29-2004 07:39 PM               

So, to answer our question, "Where does space begin?" we can only reply, "Depends on who you ask!"

posted 07-30-2004 07:17 AM               

quote:

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Originally posted by Rob Joyner:
Like the absolute moment and height at which things begin to float?

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posted 04-09-2009 10:18 PM               

Hold on to your hats, or in this case, your helmets: Scientists have finally pinpointed the so-called edge of space -- the boundary between Earth's atmosphere and outer space.

With data from a new instrument developed by scientists at the University of Calgary, scientists confirmed that space begins 73 miles (118 kilometers) above Earth's surface.

A lot remains very fuzzy, however, as the boundary is surrounded by a host of misconceptions and confusing, conflicting definitions.

posted 04-09-2009 11:19 PM               

Space to anyone of us really begins at about twenty-two to twenty-five thousand feet.

At twenty-two to twenty-five thousand feet, we can't live without survival equipment, so we really are in space.

We've been flying in space as far as our environment goes for many years. But as far as getting higher that's just one more step.

posted 04-10-2009 07:38 AM               

From the ground up:

• Strato-sphere (12 km)
  
• Tropo-sphere (50 km)
  
• Meso-sphere (90 km)
  
• Thermo-sphere (500 km)
  
• Exo-sphere (above 600 km)

posted 07-25-2018 08:58 AM               

A close look shows that the traditional definition flies in the face of evidence, says Jonathan McDowell, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts. As a hobby, McDowell compiles an influential, detailed record of rocket launches online. "I've been making lists of rockets since I was 13," he says. He often has to decide which launches qualify as reaching outer space, and which do not. Given how low many orbiting satellites fly, the 100-kilometer limit never seemed right to McDowell. He preferred the mesopause, the coldest point in Earth's atmosphere, located roughly 85 kilometers up. (Recent estimates have bumped it somewhat higher.)

...He started with data: namely, public records of satellite telemetry he had downloaded from the North American Aerospace Defense Command about the orbits of 43,000 satellites. Most didn't matter for his project—they orbited far too high above the edge of outer space. But at least 50 had orbits that occasionally operated below 100 kilometers, such as the Soviet Elektron-4 satellite, which made 10 spins at 85 kilometers or below before disintegrating into the atmosphere in 1997. "Are you going to say [these satellites are] in space and then not in space every 2 hours?" he asked. "That doesn't seem very helpful."

posted 12-05-2018 11:26 AM               

Statement about the Karman Line

The Karman line is the 100km altitude used by FAI and many other organisations to mark the "boundary" of space. In the last few years there have been many scientific and technical discussions around this demarcation line for the "edge of space" and variance around this as a boundary condition for recognition of "astronaut" status.

Recently published analyses present a compelling scientific case for reduction in this altitude from 100km to 80km. These analyses combine data/modelling from a number of differing perspectives (latitudinal variations during solar cycles, theoretical lift coefficients for different size/configuration satellites ranging from cubesats to the International Space Station, perigee/apogee elliptical analysis of actual satellite orbital lifetimes etc) to a level that has never been done before in relation to this issue. They also provide an accurate overview of some of the historical arguments and inadvertent misrepresentations of Karman's actual analyses and conclusions from over half a century ago.

FAI has therefore been in contact with the International Astronautical Federation (IAF) to propose that an international workshop is held during 2019 to fully explore this issue with input and participation from the astrodynamics and astronautical community.

Such a seminar, to be held under joint FAI/IAF auspices, would enable discussion from a wide range of professionals with relevant expertise to analyse and discuss the issue and possible redefinition of the altitude used by international organisations including FAI to recognise human spaceflights.

If the findings lead to a redefinition of the boundary of space as it is in use by international organisations, FAI would review any performances made between today's [Nov. 30, 2018] statement and the date of implementation of the revised definition in order to ensure that these performances already take into consideration the findings as they exist today.

posted 03-01-2019 07:57 AM               

A new study from Space Physics redefines the boundaries of our planet, based on overlooked data collected at the end of the last millennium. The report concludes that the edges of the atmosphere actually extend more than 391,000 miles from the planet's surface, about twice as far as our moon.

This doesn't mean you can go moonwalking without a spacesuit, said Jean-Loup Bertaux, a study coauthor and planetologist. The hydrogen molecules that make up the outer atmosphere are so sparse that this region is still considered a vacuum. Any spacecraft traveling through it wouldn't notice a thing or be slowed by drag.

It does mean, however, that humankind has yet to leave the Earth's atmosphere.