Is the International Space Station really in outer space?

[Seret]

Is the definition wrong purely because it's simplified? If so, why is it not redefined? There's a difference between lack of detail and misinformation.

Some definitions are indeed better than others though. I think your definition from high school is not useful for describing objects in LEO.

Adulthood's borders still got officially defined with legal drinking/voting/consent ages though.

Would you consider a 16 year old to be an adult? I certainly wasn't. Hell, age of consent is about 14 in some countries. I think the simile was a good one, some transitions don't lend themselves well to sharp cut-offs.

[elanachan]

In black and white film photography when making an enlargement, any amount of exposure beyond a certain point to the photo paper will turn the paper absolute black once developed, otherwise known as Zone 0. On the opposite end of this is paper which is a perfect white when it has had no exposure, referred to as zone 9. If I were to use this analogy, the planet surface could be represented by zone 9 with space being zone 0, zones 8 through 1 would be the gradual dissipation of the atmosphere as altitude is gained. Being this is a gradient scale, there are an infinite number of fractional values. However, what I have read would suggest the ISS is somewhere between zone 1 and zone 3.

[NASAFanboy]

In black and white film photography when making an enlargement, any amount of exposure beyond a certain point to the photo paper will turn the paper absolute black once developed, otherwise known as Zone 0. On the opposite end of this is paper which is a perfect white when it has had no exposure, referred to as zone 9. If I were to use this analogy, the planet surface could be represented by zone 9 with space being zone 0, zones 8 through 1 would be the gradual dissipation of the atmosphere as altitude is gained. Being this is a gradient scale, there are an infinite number of fractional values. However, what I have read would suggest the ISS is somewhere between zone 1 and zone 3.

However, Zone 0 will also have atmospherical particles from earth's atmosphere.

It is impossible to maintain a orbit inside a atmosphere, which is why the official definition is, will be, and shall be 100. Kilometers above the surface of the Earth, which is the most minimal distance a orbit can last without constant boosts (I.e one every minute).

That's why the ISS is in space, not in the upper atmosphere.

[Streetwind]

It does beg the question if, in some far off future, where humans are living on one or more worlds, would space have to be defined differently for each one, since different atmospheric densities and gravitational masses would be a factor?

That's why a definition like the Karman line can be handy: any world with an atmosphere automatically has one. On any world with an atmosphere there will come a point at which the speed to generate lift for atmospheric flight reaches orbital velocity, and you cease performing atmospheric flight at all in favor of spaceflight. Thus all worlds can use this definition of "outer space is above the Karman line" safely. It's just that each world's individual Karman line will be at different heights, and not the one we know from Earth.

Worlds without an atmosphere capable of supporting atmospheric flight obviously do not have a Karman line. You can treat those much like the Mun; any orbit that doesn't plaster you face-first into a local geographic feature is a good orbit, regardless of height. Except maybe for that weird corner case world that has a really thin atmosphere; just thin enough to make close orbits decay, but never thick enough to allow atmospheric flight. Who knows, Mercury might be such a weirdo. I mean, it's a weirdo in the first place for having an atmosphere at all, considering how small and how close to the Sun it is. it's very very thin; I'm not exactly sure how thin, and if it's enough to affect a close orbit.

[elanachan]

However, Zone 0 will also have atmospherical particles from earth's atmosphere.

It is impossible to maintain a orbit inside a atmosphere, which is why the official definition is, will be, and shall be 100. Kilometers above the surface of the Earth, which is the most minimal distance a orbit can last without constant boosts (I.e one every minute).

That's why the ISS is in space, not in the upper atmosphere.

But the ISS IS in the upper atmosphere, you are in the atmosphere until you pass beyond the exosphere, which starts nearly 200km above the altitude above the station. It seems to me what the kerman line really represents is the boarder between the lower and upper atmosphere. Going back to the high school definition, simplistic or not, outer space starts where, with the exception of gravity, atmospheric drag and other factors cease to exist. This would be where an orbiting object is able to 1. stay in an indefinite orbit, or 2. be in what is essentially a lengthily hyperbolic orbit such as our moon.

Edit: If it is the case that atmospheric drag and other factors ceases at a constant altitude within the exosphere, as apposed to this area being the outer edge of this atmospheric layer, the only exception to the rule I can think of where you can be both in an atmosphere and in outer space would be the extreme edge of the exosphere. When it comes down to it, I might be missing some history, but technically I'm wondering if we've had anything manned beyond the boarder of what I'm trying to describe at any time after the end of the apolo program.

Edit 2: If the upper atmosphere is defined as the atmosphere above where clouds cease to form, I'm thinking a third category should be put in place, a middle ground between that point and the karman line.

Edit 3: After looking up some more information, it is suggested that anything that is in a low earth orbit (this range extends out to about 2,000km) is not truly in outer space and seems to confirm we haven't had a manned flight beyond the limit I'm trying to describe sense the end of the apolo program. That being said, a medium earth orbit (MEO) according to what I'm reading does not encounter atmospheric drag and might be the boundary I've been looking for. It is worth noting that this zone overlaps with the exosphere, which would be a possible case of where outer space and the atmosphere might overlap if definitions are adjusted, however going back to the high school definition, it might be said that outer space starts within the zone defined as MEO, with high earth orbit starting at 35,766km according to wiki, which is beyond one of the limits given for the outer edge of the exosphere.

Edited April 11, 2014 by elanachan