5 ms·
The article mixes all sorts of units but doesn't say exactly where the Kármán line is supposed to be in any single unit. The closest it gets is 50 miles plus 60
by kijin 7y ago
The article mixes all sorts of units but doesn't say exactly where the Kármán line is supposed to be in any single unit. The closest it gets is 50 miles plus 60,000 feet, which is a rather confusing way to say 98.75 kilometers.
The actual Kármán line is at 100 kilometers.
This rocket reached an altitude of 339,800 feet, or 103.57 kilometers. Its maximum speed of 3,386 mph (assuming "normal" miles, not nautical miles) is equivalent to 1.513 kilometers per second [fixed]. It's well below orbital velocity, but good enough for poking into space and coming back down.
- aerophilic 7y agoThere is quite a bit of debate around where the “Karman Line” should really be (the boundary to space). Recently there have been efforts to define it as less stringent than the 100km limit: https://www.sciencedirect.com/science/article/pii/S0094576518308221 https://www.sciencedirect.com/science/article/pii/S009457651... Potentially bringing it back down to 80km (the original definition was a range between 70-90km).
- luizfzs 7y agoWe can use Kerbal Space Program as base and set it to 70km
- CydeWeys 7y agoI know you're joking, but, KSP models a planet that's different from Earth in a number of ways. On Kerbin there is zero atmospheric drag past 70km; it's not the edge of space, it's the demarcation line at which indefinite stable orbits are possible. That is very different from Earth.
- fernandopj 7y agoKSP is a whole different beast if you use the Real Solar System mod (which you should, once you learn the basics).
- CydeWeys 7y agoOne of the differences of that mod is that it changes the 70k value to what it actually is in the real world, though.
- thaumasiotes 7y ago> it changes the 70k value to what it actually is in the real world, though. This surprised me. What is the real-world altitude at which there is zero atmospheric drag? I thought the atmosphere was basically just continuous.
- marcosdumay 7y agoKerbin is designed as smaller than Earth and with a thinner atmosphere. The end result is that it's much easier to make a rocket there.
- vkou 7y agoKerbin has a soup-like lower atmosphere, and is much smaller, and much denser than the Earth.
- mannykannot 7y agoWikipedia [1] quotes from Kármán's autobiography where he discusses the origin of his idea, and he used an example of 300,000 ft. (91 km.) As the paper you link to shows, it is one of several candidates for the 'edge' of space, and they are all inherently vague. The paper shows how, by picking one reasonable set of parameters, you can put a Kármánesque line at 80 km., but its strongest argument for space beginning there is that several different candidates overlap at around that altitude. [1] https://en.wikipedia.org/wiki/K%C3%A1rm%C3%A1n_line https://en.wikipedia.org/wiki/K%C3%A1rm%C3%A1n_line
- lutorm 7y agoMaybe space should be defined as the altitude you need to have to not have your orbit decay in less than one orbit. I wonder what altitude that is, actually.
- mannykannot 7y agoThe paper linked to by aerophilic goes into that issue in some detail, but it does not lead to a sharp distinction, either - for one thing, the ballistic coefficient ranges over a couple of orders of magnitude, with smaller objects coming down sooner. If we confine the discussion to circular orbits, it suggests that 100km is a better number than anything lower, but elliptic orbits can get away with lower perigees, which is a concern when the boundary of space is being defined for national territory purposes (e.g. spy satellites with a perigee over the nation being spied on.)