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Archive 1

Term

Since the FAI uses the term Karman line wouldn't it make sense to create a page to that effect and to redirect one of these to the other?

Ooops, I see that's been done already. JimD 21:24, 2004 Jun 21 (UTC)

The U.S. definition

Most of the following is copied from Reubenbarton's and my discussion pages:

Reubenbarton, I'm just writing to tell you that I feel it was extremely rude of you to add this change to the Boundary to space article. What I'm fired up about is not as much that I feel that this info doesn't belong there, but the fact that you submitted this as a "minor" change (which it clearly wasn't).

Regarding the Gagarin/FAI statement itself: I don't know whether it's true or not, and frankly, I cannot be <behind>ed to check (any resonable person would consider Gagarin's flight a spaceflight). In any case, this info just doesn't belong in that article. I understand how the preceding paragraph might have prompted you to add it, but it still doesn't belong in that article. Besides, nobody in their right mind would take the reported cynic's claims seriously anyway and the info on it is more of an attempt to refute it than anything else.

And yes, I know I shouldn't get protective of articles I started because I don't own them after submitting, but there you go.

Ropers 20:03, 25 Jul 2004 (UTC)

The sources for the Gagarin statement are:
 The Encyclopedia Astronautica - Vostok 1:
 http://www.astronautix.com/flights/vostok1.htm

"...Gagarin ejected after reentry and descended under his own parachute, as was planned. However for many years the Soviet Union denied this, because the flight would not have been recognized for various FAI world records unless the pilot had accompanied his craft to a landing."

and the FAI Sporting rules on Astronautics: http://www.fai.org/sporting_code/sc08.pdf

"2.12.4 The pilot and crew of an aerospacecraft shall remain inside the vehicle during descent and landing. For spacecraft any method of descent and landing is acceptable provided the method is described in detail in the pre-flight plan."

What is the reference for this statement?

"Some cynics argue that the U.S. definition exists solely for historical reasons, because after the Yuri Gagarin PR disaster the U.S. needed an astronaut, and fast, so they might have decided to lower the bar a bit." Rusty 22:54, 25 Jul 2004 (UTC)

Hm. I noticed that the above FAI pdf is dated 25 April/1 August 2003, so this particular document isn't proof that the Soviets "cheated against FAI rules" (because it doesn't say what the rules were in 1961.) But anyway. Maybe they did, maybe they didn't. This particular issue/clause certainly wouldn't make me consider Gagarin's flight less of a spaceflight. If you've got clear proof then maybe this could... oops, ok, I see you have added this info to the Vostok 1 article. So then I think it can't hurt to back up this change/charge with some bulletproof evidence.
Talking of bulletproof evidence, I don't have such for the paragraph reporting the cynic's view on the U.S. definition. It's just something I heard people say, like, repeatedly over here in Germany. I could of course start looking for proof on the web now, but I cannot be bothered. Again, I didn't mean to have a go at the U.S. To fully quote the related sentences:
Some cynics argue that the U.S. definition exists solely for historical reasons, because after the Yuri Gagarin PR disaster the U.S. needed an astronaut, and fast, so they might have decided to lower the bar a bit. If that were true however, it would have been an unnecessary step: Alan Shepard, the first U.S. astronaut, travelled 185 km (115 miles) up.
Again, my intention was not to slander the US, but to put the cynic's claims into perspective: Alan Shepard travelled 185 km up, which kinda tells something about the aforesaid cynic's interpretation.
All that said, I wouldn't scream murder if the above sentences got removed. It's only vaguely related trivia anyway and doesn't offer hard and fast evidence on how the U.S. definition was arrived at. To play it fair, you could e.g. call a vote (to potentially facilitate which I copied this stuff to/wrote my response (here) at Talk:Boundary to space.)
Ropers 19:48, 26 Jul 2004 (UTC)
No I wouldn't think of changing the statement. You insist on including it and your admission that you can't be bothered looking up facts and to placing POV unsubstantiated statements in the article should stand on their own. These kinds of facts should help readers to decide on the value of the article.Rusty 03:07, 27 Jul 2004 (UTC)
Oh come on! Do you absolutely, positively WANT to believe that I'm "teh enemeh"? Are you so keen on believing that my intention was sinister and not to inform of alternative and/or non-US point of views? Is it so hurtful to you to even learn of the existance of such views? Do you have to shoot at the messenger because you think the messenger agrees with the message? Despite me making it very clear that if anything, the opposite is the case? Listen: I've removed the said sentences. If people want to put them back in, fine, but I'm not going to touch them anymore. I cannot help but feel sorry: It must be really frightening to live with a frame of mind where the world appears to be out to get you. Ropers 18:53, 27 Jul 2004 (UTC)
Just remember, it is not I who have removed a single word from the article. It is you that chose to practice censorship and I didn't make a move to reverse it. I just expressed my views in the discussion page after being attacked and called "rude" for just doing what Wiki is about. You mentioned Gagarin in the edge of space article and so did I. I backed my statement with sources (here are additional sources: Encyclopedia Astronautica, BBC Science page, WWW.Worldspaceflight.com, WWW.Space.com) and you did not. I ask for a source and get a aspersions and false pity heaped on me. That must mean you don't have a source. I invite you to read the latest version of the Vostok 1 article. I believe it has a neutral POV. It states the facts of the flight. I have also built a timeline of the flight from various internet sources. Have a nice day. Rusty 21:36, 27 Jul 2004 (UTC)
Right. So marking a real change as a minor edit is "doing what Wiki is about"? Are you at all familiar with this Wikipedia policy? And since when does removing off-topic info from a specific article equal censorship? I felt your initial action was rude against the backdrop of accepted Wikipedia policy. You accuse me of practicing censorship based on what? Show me I've behaved badly and I'll apologize. Ropers 13:46, 28 Jul 2004 (UTC)

Boundary of Space

Wouldn't Boundary of Space make a much better title? I have never heard anyone say "boundary to ________", only "boundary of __________". Besides, it is the boundary of space. Or perhaps if you'd rather the "Boundary of Earth's Atmosphere"? Well, I will let you decide, and perhaps if no one replies I will move it. Moogle 05:41, 30 Sep 2004 (UTC)

Also see the article on the Kármán line under External links below, which has an excellent explanation on how this boundary was determined.

The explanation should be incorporated into the article, not mentioned in passing. --[[User:Eequor|η♀υωρ]] 01:48, 5 Oct 2004 (UTC)

AP magnetic index

Hi. The article uses the term "AP magnetic index", which is mysterious to this casual reader, and which Wikipedia doesn't have an entry for. Reading this page I'm thinking a better substitute is "fluctuations in the Earth's magnetic field". Does that seem right? William Pietri 06:21, 20 September 2006 (UTC)

image

it would be neat if the image were broken up and displayed on each of the pages for spheres, and each section of the image were clickable and went to the article on that sphere. but still looked the same as it is. probably possible with a table. like an "atmosphere taxobox". - Omegatron 01:08, Jan 8, 2005 (UTC)

It would also be better if the image showed the Karman line. User:Zntrip00:44, 15 August 2005 (UTC)

yeah, I agree. am I allowed to edit the image to include the karman line? (not sure about copyright issues) --75.108.173.67 10:34, 17 October 2006 (UTC)

Boundary to space / Karman line as title

(William M. Connolley 17:38, 28 Nov 2004 (UTC)) It seems very odd to me to use Karman line as the "main" title for this page rather than the far-more-obvious boudary to/of space.

Boundary to space is certianly more clear and specific, but is there such a thing? Duk 18:29, 28 Nov 2004 (UTC)
(William M. Connolley 19:44, 28 Nov 2004 (UTC)) If there isn't such a thing, then the article is in need of revision: The boundary to space or edge of space, according to definitions by the Fédération Aéronautique Internationale (FAI), lies at a height of 100 km (about 62 miles) above Earth's surface (ie. in technical terms 100 km above mean sea level).
Yes, good point. Further down in the article there is a note;FAI apparently doesn't itself use the precise words "boundary to space" or "edge of space". Duk 19:58, 28 Nov 2004 (UTC)
Some of the sections should be moved to outer space.
I think that "Karman line" is a more appropriate main title for this page. The article states "Strictly speaking, there is no such thing as an end to Earth's atmosphere: An atmosphere does not technically end at any given height, but becomes progressively thinner with altitude." The article is about the line which is used to determine at what point something is considered to be "in space", not about a location where the Earth's atmosphere suddenly ends and space begins. Since there is technically no "edge of space", and the aticle mentions this fact repeatedly, I don't think it makes sense to call the article "Boundary of Space". --Vsst 03:30, 20 March 2007 (UTC)
Agreed. This article is not about the (singular) boundary between the atmosphere and space. Instead, it is about the altitude at which conditions change such that astronautics rather than aeronautics is the relevant engineering discipline involved in flight. (It's unfortunate but understandable that the FAI also uses it as the altitude at which travelers are considered to have become astronauts.) Sdsds 04:51, 20 March 2007 (UTC)

Karman line equivalents

Has anyone ever calculated the equivalent of the Karman line for other planets, such as Mars, for example.

Apparently not, but it would be a great addition to this article to find a source that has done so! For that matter, it would be great to find a source the explains the calculation Kármán did to get approximately 100 km for Earth. (Musn't the calculation assume something about the maximum ability of a wing to create lift at a given air pressure, and something about the decrease in air pressure as altitude increases?) Given a recreation of the calculation for Earth, creating one for Mars might be within the capabilities of mere aerospace amatuers. (sdsds - talk) 06:28, 2 September 2007 (UTC)

The Kármán line in Venus is around 250 km high, and in Mars about 80 km [1].

Copyvio

In looking for references, I noticed that much (not all) of the article is reproduced directly from this one:

http://www.angkasawan.com.my/mainatsb/atsb/humansspace.html

Again, the entire article is not copied, but many sentences are duplicates from the website. E_dog95' Hi ' 23:04, 29 April 2008 (UTC)

I believe it is the other way around, if there is a connection. Looking through the article history, there is no point at which the wording of this website was suddenly adopted. Indeed, the very first revision starts with “Strictly speaking of course, there is no such thing as an end to earth's atmosphere: The atmosphere doesn't technically end at any given height, but it gets progressively thinner the higher you go.” The article progressed organically from there. EdgeOfEpsilon (talk) 21:56, 19 May 2008 (UTC)

The article was started by User:Ropers (note the date of the first edit, 20 June 2004). It was initially named Edge of space, but then moved around quite a bit, first to boundary to space, then Karman line, then Kármán line. Now note the date the above website was created: 

$ whois angkasawan.com.my

Welcome to MYNIC Whois Server.
--------------------------------------------------
  For alternative search,
   whois -h whois.mynic.net.my xxxxx#option

  Type the command as below for display help: 
  whois -h whois.mynic.net.my #h

--------------------------------------------------

SEARCH BY DOMAIN NAME

a [Domain Name]             angkasawan.com.my
b [MYNIC Registration No.]  D1A076017
c [Record Created]          15-MAR-2007

The above website has definitely copied from Wikipedia, not the other way around. I am removing the copyvio template, but maybe someone wants to check if the other website is in GFDL compliance and contact them if applicable?. 86.56.122.190 (talk) 21:29, 31 May 2008 (UTC)

Use of "edge of space"

The FAI apparently does not itself use the precise words "boundary to space" or "edge of space"

Some people (including the FAI in some of their publications) also use the expression "edge of space"

These 2 statements seem contradictory. Which is correct? AstroMark (talk) 22:16, 18 June 2008 (UTC)

Neither statement belongs in the article without a reference citing a reliable source. Wikipedia:Verifiability, which is policy, reads: "Editors should provide a reliable source for quotations and for any material that is challenged or is likely to be challenged, or the material may be removed." (sdsds - talk) 23:03, 18 June 2008 (UTC)

Need new article

This article, Kármán line is great. But as a recent IP edit notes this article isn't about the "Boundary of space"; this article is about one definition of the boundary of space. The IP editor removed the section of this article discussing e.the U.S. definition of "astronaut" and the altitude required for astronaut wings. Rightly so! This article is about the Kármán line, for which the U.S. definition isn't relevant. What wikipedia needs is a new Boundary of space article which doesn't redirect here, but which instead references the Kármán line article and then mentions other definitions as well. (sdsds - talk) 05:03, 20 July 2008 (UTC)

I changed the article before I noticed your comments here. I put the material back and renamed it. I just wanted to say that and that your new article idea sounds fine. E_dog95' Hi ' 20:04, 20 July 2008 (UTC)

Space does not equal orbit

There has been a tendency to document so-called "common misunderstandings" in these space and orbit related pages on Wikipedia. For every fact, it seems to me, there are a hundred possible misunderstandings. We are having enough difficulty documenting the facts, nevermind supposedly "common" misunderstandings. This is not supposed to be an encyclopedia of common misunderstandings.

But even if it were, the "common misunderstanding" documented in this article, that "space does not equal orbit" is not "common" in my experience. I have never, ever heard or read that reaching space was misunderstood as reaching orbit. I think possibly what is happening is that an editor (or editors, but I think there is only one) is documenting his own misunderstanding or the misunderstandings of a colleague or family member.

It also seems to me that a "common misunderstanding" which can be resolved by simply referring to a dictionary should rarely, if ever, be documented here for the well established reason thet Wikipedia is not a dictionary: We do not provide dictionary definitions. Nobody who is prepared to refer to a dictionary could confuse entering space with performing an orbit.

We must provide encyclopaedic articles on both Earth orbit and this subject, the boundary to space. That some may confuse the two is no more likely than many other confusions. If there are 1000 distinct, unrelated facts then 1,000,000 false connections between them could possibly be arrived at by the ignorant. We can document the 1000 facts not the 1,000,000 false connections: We cannot hope to double guess the wilfully ignorant by deciding which of the 1,000,000 possible misconceptions we must debunk.

Were I to trawl through Wikipedia recording all of my previous misconceptions I would create a lot of useless noise and annoyance, even if I just did the ones I felt were common. F'rinstance: I once thought, a long time ago, that Spain was the capital of France. Once of my other childish misunderstandings but apparently one which is fairly common was that you see in a radar-like fashion by emiting a beam from one's eyes. In a similar theme I also was convinced, as are many, that electricity travelled outbound along the red wire and the black wire until it met at the lightbulb where the collision caused the light. And a more serious misunderstanding, commonly held, was that wood came from stuff sucked up from the ground whereas mostly the mass of wood comes from the air. But these misunderstandings, and many others like them, I am not going to document in the articles here at Wikipedia unless someone starts an article of common and comical misuderstandings

For these reasons I intend to replace the section with a simple reference such as See also: orbit. But I also intend to remove it because it is plainly off topic. Comment invited.

Paul Beardsell 10:32, 3 Oct 2004 (UTC)


Now this is very interesting. I've never heard that "space equals orbit" is a misconception at all. On the contrary - I know a space lawyer (Dr Gyula Gál, from Hungary, member of International Institute for Space Law), who's been with international collegues for many decades arguing that we should adopt a "functional" definition of space activities - that is, of considering an activity "space activity" if it is an orbital activity, or at least part of an orbit (if I get it right - someone with more knowledge pls correct). So eg. a balloon or a rocketplane flight would not be space flight, even if it goes to a hundred km (and so considered to be in the airspace of the given country). Sweden eg. doesn't define a suborbital research rocket as spacecraft even if it goes above 100km.

One problem with the 100km (or whatever) line comes from the fact that as long as the craft is under 100km, it will be in the airspace of a country. And in some countries (which are too small), it'll necessary go in another countries airspace before reaching 100km or orbit. So these guys claim that space activity begins with launch and ends with landing, and this whole process should be treated as being in space (applying the relevant international space treaties for search,rescue and disaster payments etc)

Another topic is about self-defence: for defending against ICBM etc, countries don't look at strict limits of air sovereignty. Eg. Hungary defines air sovereignty where air travel is physically possible, so about 35-40km, but would (if were able to...) defend herself at higher altitudes if necessary.

The UN Committee on the Peaceful Uses of Outer Space has been arguing over it for decades (since 2222/XXI on 1967), and they (contrary to the FAI) have not reached decision. Of course, it is much less of a significance for the FAI, it's only record-keeping; but for UN it's about law and sovereignty.

So I think this article should mention this problem. After all, the UN/COPUOS is at least as great a body as FAI or US. (Actually who cares about FAI? As someone pointed out, they wouldn't even treat Vostok-1 as spaceflight... who asked them anyway?)

Article in Hungarian: http://jura.ajk.pte.hu/cikkek.php?cikk=22

There's probably much more (and in English) hidden at http://www.iislweb.org but it's too much (and legalese) for me to read through now.

Hoemaco (talk) 05:49, 7 October 2008 (UTC)

A different boundary of space

Edge of Space Found

The proposed limit is 73 miles/118 kilometers. RandomCritic (talk) 02:23, 10 April 2009 (UTC)

Andrew G. Haley

Shouldn't the fundamental role of Andrew G. Haley be mentioned in this article?[1][2] Regards, RJH (talk) 23:21, 23 October 2011 (UTC)

Proper noun pedantry

To be very pedantic, shouldn't it be "Kármán Line" as the full term is a single proper noun? (e.g. Eiffel Tower, Grand Canyon). 121.98.218.165 (talk) 02:49, 15 January 2012 (UTC)Martyn

History/Adoption

When was the Kármán line defined/adopted? That information should be in the article but currently isn't. 31.18.253.188 (talk) 03:52, 30 April 2012 (UTC)

Orbital velocity vs. escape velocity

Multiple times, this article uses the term orbital velocity and links to the orbital velocity article. The problem is, that's not an article; it's a disambiguation page, and we're not supposed to link to those. And none of the three articles the disambiguation page points to match the way the term is used here. The closest match is orbital speed, but that's just the speed of an orbiting object. I think escape velocity is what was intended, but perhaps there's some nuance I'm missing. If escape velocity is in fact the right term, then why don't we use that term? Is orbital velocity a synonym for escape velocity in some regions or contexts? Please comment if you know more. —mjb (talk) 23:42, 28 October 2012 (UTC)

Orbital velocity in this article presumably refers to the speed necessary for a circular orbit of a given height, 100 km in this case. Escape velocity is the speed necessary to completely escape the Earth (keep moving away and never come back) starting from a given height. Escape velocity is always 1.414 (square root of two) times faster than the orbital velocity of a circular orbit at a given height. Brian Wowk (talk) 05:17, 1 May 2013 (UTC)

Is centrifugal force included in the Karman Line calculation ?

Neither the article, the source it points to, or other sources I can find, clearly state whether weight reduction due to centrifugal force is considered in the calculation of what speed a vehicle must travel at to generate sufficient aerodynamic lift to support itself. To illustrate the problem, it makes no sense to say "any vehicle at this altitude would have to travel faster than orbital velocity in order to derive sufficient aerodynamic lift from the atmosphere to support itself" because a vehicle at orbital velocity needs no aerodynamic life to support itself against falling back to Earth. The centrifugal force associated with orbital velocity reduces the vehicle's effective weight to zero, which is the meaning of being in orbit. So what's the deal? Perhaps the Karman Line is the altitude at which orbital velocity is necessary to generate aerodynamic lift equal to the vehicle's own weight at rest? In other words, it's the altitude at which orbital speed is necessary to keep flying in a straight line rather the follow the curve of the Earth? That seems to make the most sense since 100 km is already sensible atmosphere to reentering spacecraft, and a back-of-the-envelope calculation shows that vehicles hitting atmosphere at that altitude at orbital velocity would experience on the order of one gee of force. I'll edit the article to clarify this point. An interesting implication is that contrary to Karman Line descriptions, you can in fact use aerodynamic lift to remain aloft at altitudes above the Karman line while traveling at speeds somewhat less then orbital (if you can take the heat). This is how reentering spacecraft hitting Karman line altitudes at orbital velocity at shallow angles can actually bounce off the atmosphere back into space. They still "fall" in the sense of following a trajectory curved toward the Earth due to insufficient lift, but Earth's surface curves away faster. Brian Wowk (talk) 07:04, 1 May 2013 (UTC)

"International Law" definition

I've done some pretty extensive research on this, and no where can I find any source stating that in International Law space is defined as it says in this article. In fact, based on this United Nations memo I'd say it is pretty definitive that the UN has NOT agreed on any such definition: http://www.unoosa.org/pdf/limited/c2/AC105_C2_2012_DEF_L01E.pdf — Preceding unsigned comment added by Spaceguy2015 (talk • contribs) 21:03, 2 May 2015 (UTC)

Clear it up

Can someone clear this article up. The americans tried to invent a fake definition of what Space was so they could hand out medals and pretend some dead pilots were astronauts. It should be mentioned as an aside but some derper seems to be trying to pretend it's a legitimate definition. There doesn't seem to be any mention of other fictional beliefs like the vault of heaven or Apollo's chariot. — Preceding unsigned comment added by 79.97.159.72 (talk) 02:07, 27 August 2015 (UTC)

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About lifting limit

That is a troublesome definition. Isn't the aerodynamic lift dependent on technology? I mean, a glider has a better lift than, say, the space shuttle. Thus advances in technology will push away the limit of space, and before the Wright brothers, space started at 0km??? Tony (talk) 15:20, 10 April 2009 (UTC)

I think that flight utilizing aerodynamic lift has been around since the Carboniferous. RandomCritic (talk) 15:53, 11 April 2009 (UTC)

I do think the same, Bruguiea. What kind of vehicle did Kármán take when doing his calculations? If you take a plane and other with wings two times longer, but a same weight...--Andrestand (talk) 17:42, 2 June 2009 (UTC)
I have a friend who used to be an aeronautical engineer. I was discussing space (and Kerbal Space Program) with him and mentioned the Karman Line, which he hadn't heard of. I explained it in the same terms as this article - that it's the altitude where your airspeed must be so fast that it's orbital velocity. He immediately said "but your lift depends on your wing area as well. What size wing are we talking about?". So, what size wing ARE we talking about? If your wing area was big enough, could you not get above 100km without reaching orbital velocity? — Preceding unsigned comment added by 49.183.192.203 (talk) 01:42, 21 July 2016 (UTC)

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Section "Kármán's comments"

So matta'fact, Kármán defined the space boundary at a height of 91.440 meters / 57 miles, so the true Kármán line is not on 100 km. --212.186.7.98 (talk) 16:09, 18 December 2017 (UTC)

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this article gives off a far too definitive impression

Editing to better match how 100 km wasn't Karman's own figure, and how there is far from consensus on the 100 km figure, and that FAI itself is considering a change CapnZapp (talk) 09:15, 14 December 2018 (UTC)

First off, the lead section now talks about the Karman Line as a definition, not the definition of the edge of space. Then I've added something that I feel should be in the lead: I've attempted a layman's explanation of why this is important - feel free to further improve, but keep in mind this does not attempt minute exactness - it's meant to explain the issue for ordinary readers. Then its important to already in the lead summarize the later sections on how the FAI definition is not what Karman himself arrived at, and how other organizations use other figures, or don't recognize any defined limit at all. This because it makes it clear the 100 km figure is not some constant of nature - instead it is an arbitrary nice and round figure. I decided to withhold the part about changing the definition; reading sources more closely I realized this is not at all (yet) on FAI's official agenda, and that many popular science magazine headers are misleading. CapnZapp (talk) 09:48, 14 December 2018 (UTC)

also autoarchive

Notifying planning automatic archival of this talk page CapnZapp (talk) 09:16, 14 December 2018 (UTC)

 Done This page might seem a bit bare atm, but it is because the very oldest entries had to be manually archived. (You do not need to change the autoarchival parameters) CapnZapp (talk) 10:14, 21 December 2018 (UTC)

Definitions lacking??

To begin with, the article says:

The amount of lift required at any given point can be calculated by the lift equation ...

Actually, the lift REQUIRED to hold an aircraft up is equal to the weight of the aircraft (figuring in also any centrifugal effects--more on that in a moment). What the equation gives is the amount of lift produced under given circumstances. I'm going to reword that when I finish here.
All that said, there must be some basic assumptions to the definition--assumptions not accounted for in the article. The definition is, basically, the altitude at which--given the thinness of the air--an airfoil-dependent aircraft would, in order to generate sufficient lift to stay aloft, need to achieve a speed equal to orbital speed at that altitude. But that would depend on the aircraft.

  • First, different airfoils--different wing shapes and sizes--would provide different lifts.
  • Second, a lighter aircraft requires less lift.

I think the definition must have included some basic assumptions about the aircraft.
In addition to all that, the points about centrifugal force must also have some assumptions not addressed here. Consider that:

  • If you're flying at the equator, going East at 1000 mph airspeed, for purposes of centrifugal force, you're going 2000 mph, because the Earth is turning at 1000 mph at the Equator.
  • If you're flying at the equator, going WEST at 1000 mph, for purposes of centrifugal force, you're standing still.

So the centrifugal force depends on where you are and what direction you're flying. Uporządnicki (talk) 18:40, 2 January 2019 (UTC)

  • You seem to have completely misunderstood the paragraph, as it was.
Also, please don't introduce misleading claims about centrifugal force. They're not relevant to this article, and the effects are very small (about 0.3% g) Andy Dingley (talk) 19:27, 2 January 2019 (UTC)

I didn't introduce them; relevant or not, the article introduced them. In two different paragraphs. (OK, so one's a quote--and we can't alter that for accuracy.) And what I said was not misleading. Also, once one gets up to this Karman line, if one then achieves orbit, then the effect of centrifugal force gets to be 100%--not very small. Uhm, but I am correcting just now an apparent misstatement of mine above (I omitted the word "depends").

The article currently mentions centrifugal force in relation to an orbiting body, or at least one travelling at high speed, sufficiently high for that speed to contribute a significant change to its weight. However your comments have been in relation to the Earth's rotation, i.e. lower than this. And, as noted, insignificant as such a change. Andy Dingley (talk) 19:55, 2 January 2019 (UTC)
I moved this response of yours to the appropriate discussion; you had it appended to one where it didn't apply. You're welcome.

First, the article is largely about the point at which aerodynamic lift is superseded by orbital dynamics. Second, the article also does acknowledge that centrifugal effects have some tiny effect on flying aerodynamically. Since the article raises all--I didn't--I don't see the objection to my discussing on the discussion page.

Believe I corrected a point--someone reverted me

OK, I want to try and avoid an edit war here before it starts. So let me throw this question out for discussion. I made a revision here, earlier today. The article said:

The amount of lift required at any given point can be calculated by the lift equation:

I edited it to say:

The amount of lift provided by a given airfoil at any given point can be calculated by the lift equation:

I explained my thinking that the equation does NOT give lift REQUIRED, but it gives the lift PROVIDED. In my comment above, I expanded on that, explaining that the lift REQUIRED is equal to the weight of the airplane; that, after all, is what needs to be lifted. The equation gives the life PROVIDED, by a given airfoil under given circumstances. If that's enough to lift the plane, it will; if not, it won't.
Someone reverted it, giving as the reason that it was "clearer" before.
I maintain that it's not about which is "clearer." It's about the fact that the statement before my edit was incorrect. Uporządnicki (talk) 19:53, 2 January 2019 (UTC)

  • You "corrected" a point. But it wasn't wrong beforehand. Also its implicit causality was correct, before you reversed it.
"The amount of lift required at any given point can be calculated by the lift equation"
is a statement about considering the amount of lift required to attain flight. It is then used to derive a relationship with air density, hence the relevance here. Your version seems to be digresssing into how much lift (a value we don't even care about here) is provided by particular airfoils. Yet the behaviour of different airfoils is already accounted for by the lift coefficient . And again, it's just not relevant here – we're here to derive a relationship to the air density . Andy Dingley (talk) 20:04, 2 January 2019 (UTC)

The equation gives the amount of lift PROVIDED. The statement is about the equation. It seems to me that without knowing it, you've made two good cases for my point.
And again, the amount of lift REQUIRED is the weight of the airplane. Uporządnicki (talk) 20:17, 2 January 2019 (UTC)

I correct myself: you've made THREE good cases for my point. Uporządnicki (talk) 20:19, 2 January 2019 (UTC)

Dear Mr. Dingley--a good-faith suggestion

Dear Andy Dingley. At this point, may I make a sincere suggestion. It seems that at the moment, we're approaching a condition of Loggerheads, if we're not there already.

  • I firmly maintain that I corrected an error.
  • I gather that you maintain that the "error" was not an error, and I'm confusing things and introducing irrelevancies.

I've asked on the WikiProject Spaceflight page that others come in and have a look at things, and tell us what they think. May I suggest we both step back and see if anything comes from that.
Thank you. Uporządnicki (talk) 20:28, 2 January 2019 (UTC)

You are correct; the equation does not calculate "the lift required", which equals the weight of the aircraft! The lift equation provides the amount of lift supplied by the complete airframe, not just the airfoil (wing). JustinTime55 (talk) 21:13, 2 January 2019 (UTC)
The equation can be interpreted either way, equally correctly. However the purpose here is not to characterise an aircraft design, it's to consider the boundary conditions for flight, then to analyse the effects of air density on those - i.e. the lift required. Thus the original, phrased as 'required' is better than 'provided'. Andy Dingley (talk) 21:17, 2 January 2019 (UTC)
No, "required" is definitely less clear. It's vague, since it does say what that lift is required for. Second, the equation gives the force. If you are concerned about level flight, then you have to set that equal to g m. That's done in the next equation, several paragraphs later. Fcrary (talk) 21:38, 2 January 2019 (UTC)
The equation calculate the lift one GETS, given certain factors; those factors, broadly speaking, include the aircraft design. From that, you can see what you have to change if you haven't got enough lift (and it does NOT tell you how much you NEED; you know that from how much the aircraft weighs).
In most circumstances, that would be the speed. You have a given aircraft, with given airfoil characteristics; you want to fly at a particular height--the air pressure is determined by that height; so if you need more lift, the remaining option is to go faster. The equation can tell you HOW to get the lift you need.
I was getting ready to propose another wording, but I see that someone has already edited the article to take my point into account.
Andy Dingley, I'm trying in good faith to glean where you're coming from in all this (I have no doubt you're arguing in good faith). I wonder if you've been interpreting the original wording something along the lines of: "By means of the Lift equation, one can work out HOW TO GET THE REQUIRED LIFT."Uporządnicki (talk) 14:37, 3 January 2019 (UTC)
Oh, and Fcrary, good to see you here. I've seen you before at the article on the Parker Solar Probe. I'm wondering if I can trouble you to have a look at the Talk page there; I'm contemplating making substantial revisions/additions to that table on the mission details, but I'm hoping to find out what others think about them. Uporządnicki (talk) 14:37, 3 January 2019 (UTC)

US/English/International units of measurement

First off, there is no particular reason this article should use US spelling of measurement units. Actually, there isn't any particular need for a spelling war at all, since the article is about a FAI definition, an international body who mainly uses "km" in its abbreviated form (but does otherwise use the international spelling twice as often as the US spelling).

Oh, and "kilometre" isn't the "English spelling" - it's the international spelling, used everywhere except in the US (and Philippines I guess).

I've edited the entire article for consistency. Now it uses "km" and "miles", except in two instances: first the introductory definition and in the one-time use of the {{convert}} template's |adj=on parameter (where "kilometre" does get spelled out; and is using the international spelling). We can easily rephrase the second instance to avoid more than one spelling-out of the unit.

I can also add that when the article was created back in 2004, it used "km" exclusively.

If you want to question the decisions made here, I'm open to discussion. CapnZapp (talk) 09:37, 17 July 2019 (UTC)

The use of non-American spelling for things like kilometer would produce a huge consistency problem and/or cause many arguments. The American spelling is used almost exclusively on Wikipedia spaceflight articles. Actually, Wikipedia uses American spelling for just about everything. Do you really want to get all those editors to agree it should be changed everywhere? And then make all the changes yourself? Fcrary (talk) 21:31, 17 July 2019 (UTC)
Wikipedia does not use American spelling for just about everything, see MOS:ENGVAR. American spelling is used for articles "with strong national ties" to the US, which is the case of many spaceflight articles – but British spelling is used for the International Space Station and articles relating to European spaceflight, for example. There's nothing inherently American about the boundary of space, and it's not clear whether von Kármán hypothesised this boundary before or after moving to the US. Rosbif73 (talk) 06:37, 18 July 2019 (UTC)

Why explicitly say accents are optional?

There are two issues we've had back and forth edits on. As requested, I'm moving both to the talk page (in separate sections.)

The first is in the lead, where it currently says, "Kármán line, or Karman line". Technically, the correct spelling of his name has accents. It's an accepted convention that you can leave out accents if it's inconvenient, but I think that's understood. Is there any reason to explicitly say "or Karman line"? Fcrary (talk) 07:42, 21 September 2019 (UTC)

Thank you for taking this to talk. A quick googling tells me that "Karman" is about as common as "Kármán", which per WP:DIACRITIC means we should not choose the latter over the former. I wasn't the original objector to removing the diacritic-less version, but could it be something along the idea that we should not be elitist and not even acknowledge the simplified spelling? (That we use the full name subsequently in our article is ok) CapnZapp (talk) 09:05, 21 September 2019 (UTC)
I think having both spellings in the first sentence of the article is redundant. If reduce it to one, I'd prefer the accented version since it implies (by common usage) the unaccented version; the reverse isn't true. Fcrary (talk) 10:16, 21 September 2019 (UTC)
Note that there is already a redirect from the accentless version of the name, so all we're talking about is the lead sentence. WP:DIACRITIC doesn't explicitly anything about mentioning the accentless version, and I'm not aware of any other rules or guidelines that apply. My preference would be to delete "or Karman line". Rosbif73 (talk) 09:49, 21 September 2019 (UTC)

Redirect to Atmosphere of Earth

There are two issues we've had back and forth edits on. As requested, I'm moving both to the talk page (in separate sections.)

The article currently has a link to "Earth's atmosphere", which is a redirect to "Atmosphere of Earth". Some editors seem to object to changing this to [[Atmosphere of Earth|Earth's atmosphere]]. I know there is a guideline on the subject, but guidelines (or even policies) are not hard and fast rules. Guidelines are supposed to be applied using common sense and on a case-by-case basis. I personally don't see how the justifications for WP:NOTBROKEN make sense and apply in this case. Instead of simply pointing to a rule, could someone provide a compelling reason this guideline applies in this case?

Note that there has also been some back and forth over whether the text displayed in the article should be "Earth's atmosphere" or "Atmosphere of Earth". As far as that's concerned, I agree that "Earth's Atmosphere" reads more naturally. Fcrary (talk) 07:52, 21 September 2019 (UTC)

I really don't see any more arguments than WP:NOTBROKEN already provides. Piping links solely to avoid redirects is generally a time-wasting exercise that can actually be detrimental. is plenty compelling to me. And our case is a poster boy example of the exact thing NOTBROKEN speaks of, so...? I suggest you do either or both of 1) specifying what more justification you want and 2) argue why this particular case should be an exception. (As a personal observation, Fcrary, taking the stance people need to justify why Wikipedia policies and guidelines should apply won't get you anywhere on Wikipedia.) Thanks. CapnZapp (talk) 09:21, 21 September 2019 (UTC)
As for the phrasing, since all alternatives are covered by redirects, why don't we simply use whatever phrasing feels best - slap a pair of bracers [[ ]] around that, and let the Wiki software handle everything else! :-) CapnZapp (talk) 09:21, 21 September 2019 (UTC)
I agree entirely. WP:NOTBROKEN, while only a guideline, is pretty clear. None of the Good reasons to bypass redirects that it mentions apply here. Rosbif73 (talk) 09:54, 21 September 2019 (UTC)
I'm afraid I see this as the difference between a guideline and a policy. For a guideline, someone needs to say why it does apply. That is, which item on that list of reasons not to redirect is the compelling one in this case. Guidelines are supposed to evolve based on usage (including disappearing if they stop making sense.) That can't happen if we just follow the rule because it's a rule. (Note policies, as opposed to guidelines are a bit different in this respect. That's why they are called different things.) Fcrary (talk) 10:12, 21 September 2019 (UTC)
The usual practice is to follow guidelines unless there's a good reason not to do so. In this particuar case, I don't think it really matters all that much one way or the other; I agree that none of the stated reasons for the guideline are particularly compelling in this instance, but equally I don't see a compelling reason not to follow the guideline. Rosbif73 (talk) 14:31, 21 September 2019 (UTC)

Article body not about subject

The article subject is "Karman line", but the article body is clearly about the "edge of the atmosphere". The Karman line is one definition of this edge, but there are others mentioned, and the body of the srticle clearly assumes the subject of the article is not (just) the KArman line, but various different ideas of where the atmosphere ends. The is no source saying 80km is the Karman line, but there are sources saying 80km is the edge of the atmosphere etc. I think "edge of space" or "height of earths atmosphere" or similar names would be more appropriate. 46.223.43.217 (talk) 16:52, 20 October 2020 (UTC)

It would probably make sense, given the WP:GLOBAL view that Wikipedia takes seriously, to have a bang up article on the "beginning of space" or "edge of the atmosphere" (although, I know, it's not an "edge") that is more global and have that article explicate both the IAF 100km arbitrary delineation as well as the US-used 50 miles (~80km) delineation. Karman line would obviously need to be clearly covered in a section within that, and the Karman line WP-link might usefully become a redirect at that time. Pinging editors recently interested in the quality of this page: 46.223.43.217, Fcrary, CapnZapp and Rosbif73
I would seriously participate in the discussion if any editor wants to put forward a serious proposal. N2e (talk) 01:20, 14 July 2021 (UTC)
@N2e After recent changes the article became more blurry. The article about Karman line should say what the Karman line is (100 km line established by FAI/IAF). Maybe discuss some historical background (including origins of the name). Add some technical/science facts about what happens at 100 km and maybe some about what happens at 275 000 ft (actual Karman calculations). All other stuff should be just brief mentions and maybe a link to an article about space boundaries in different institutions. Nux (talk) 01:41, 14 July 2021 (UTC)

Watch out for sniping edits by detractors

I observe several edits that purport to be neutral but with the actual agenda to downplay the importance of the article subject.

I just now realized the main source for the basic claim is by such a detractor. Start reading "THE NON KÁRMÁN LINE: AN URBAN LEGEND OF THE SPACE AGE" by Thomas Gangale and you will immediately realize how inappropriate it is for usage as the defining source for the article lead.

The article lead was reorganized with the reasonable aim to provide the definition first. However, the importance of having a definition was relegated to a subsequent paragraph.

Let's try to restore the article to its previous state while keeping the definition up front. CapnZapp (talk) 10:55, 25 July 2021 (UTC)

I have taken a stab at copywriting the lead. I have removed the inappropriate source, added another, and removed the comparison to the mesophere as not critical to the lead of this article. CapnZapp (talk) 11:08, 25 July 2021 (UTC)

"it is not clear that the von Kármán calculation and the IAF number ever had anything to do with each other."

What bollocks is this?

The FAI could just have used Karman's name to honor the idea to come up with a boundary. This sounds like you set up the claim "there is a direct link" just for it to be shot down, to cast shade on the whole notion.

Tell me why it is so important for the validity of the concept that Karman himself suggested the exact definition eventually used.

No? Well, we have loads of things named in honor of people. Very seldom do people suggest these people must be directly involved for the thing to be valid. CapnZapp (talk) 11:18, 25 July 2021 (UTC)

Edit

Starting a new section because this relates to (or could be related to) the previous four sections.

  • I've removed (reverted) the attempt to make Thomas Gangale the sole source of our editorial voice in the lead.
  • I just removed the discussion under Definition as being spurious. Previous editors tried to set up the scenario where some sources say Karman himself suggested 100 km to the FAI, and others denying this. But when I read the supplied sources I get a sidebar in an unrelated Walk of Honor article as well as that Gangale article. My suggestion is that we just remove the entire attempt to create a controversy. If you have actually good sources discussing the lead-up to FAI's definition and/or Karman's involvement, feel free to use them. You should probably not reuse the old paragraphs though (my guess you're better off writing new text than reverting to the old). This fixes the weasel inline tags.
  • Unlike in the last spat of edits I made sure to retain the Gangale source, as it is referenced elsewhere on the article page

Regards, CapnZapp (talk) 17:55, 1 August 2021 (UTC)

On von Karman's involvement, this link on the FAI's web site suggests that it was von Karman himself, in collaboration with other aeronautical and astronautical experts, who came up with the 100 km number, and intended this to be the boundary separating the fields of aeronautics and astronautics. https://www.fai.org/page/icare-boundary
He did not name the boundary after himself, that's what the FAI did later. While von Karman based his value on physical principles and came up with the 100 km as a result of calculations (and measurements known at the time), the FAI took the resulting 100 km as its definition, not the underlying physical principles.
So, is this the 'official' definition of the Karman line? Is there even an official legal definition, like for the metre, or is it an unofficial concept? As far as I can tell, the FAI is a private legal entity governed by Swiss law, not a standards body set up under international treaties. Its web site says it is recognised as an International Federation by the International Olympic Committee.
We also need to distinguish between the definition of the boundary of space and the definition of the Karman line. The two are not necessarily the same, even though von Karman intended them to be. AFAIK the Karman line has no official status under international law for defining the boundary of space, and if such a boundary were to be defined by international treaty in future, that by itself would not redefine the Karman line.
The FAI site also contains a statement (https://www.fai.org/news/statement-about-karman-line) about the possibility of changing its definition of the Karman line, and says a compelling scientific case has been made for lowering it to 80 km. It has proposed an international workshop on this topic with input and participation from the astrodynamics and astronautical community under joint auspice of FAI and the International Astronautical Federation (IAF). I have not been able to find any more information about this workshop.
The bottom line seems to be that the Karman line is informally but widely recognised internationally as being 100 km, and is more or less officially recognised in the world of sports at the same value of 100 km. Perhaps either or both of these definitions will change in future, but I have seen no evidence that this has happened yet. Martijn Meijering (talk) 22:44, 1 August 2021 (UTC)
Thank you. That link sure looks like a better source than the previous one and I welcome you to put it to use. I don't think we at Wikipedia need to worry about "official legal definition", and in fact that we should not. We just ask ourselves "is the FAI a good source?", and the answer obviously is yes. We don't necessarily need to distinguish between the The Karman Line and the "definition of the boundary of space". I think it's more constructive to say The Karman Line stands for two things, one: a specific definition (that of the FAI) and two: the very concept of "the boundary of space". That's why we already say "most agencies accept FAIs definition or something close to it". That is, they all agree there is a Karman Line, that is, they agree there needs to be a boundary between atmosphere and space. Even if they then squabble about numbers. Finally, the study into lowering the limit is briefly mentioned in the body of the article. Since nothing probably came out of it (an assumption borne out of the simple fact there is no more information) that probably is all we need to say on that point. Cheers CapnZapp (talk) 10:30, 2 August 2021 (UTC)

The Non Kármán Line: An Urban Legend of the Space Age

We need to have a discussion about the repeated insertion of this source.

Does the community (that's you) regard this source -Journal of Space Law- and author -Thomas Gangale- as credible and nonpartisan?

Because his article basically argues against the very foundation of our Wikipedia article. By its own words: "This article is in part a guided tour through legal history, and in part a discussion of the technical insignificance of the von Kármán line and why it should not be used as the basis for the legal delimitation between airspace and outer space."

Using it as just one technical expert in a long line of experts seems inappropriate. If our community concludes this article should be used, it follows we need to rewrite the entire article, since it assumes pretty much the opposite of what our article and our other sources assume. It's like adding climate deniers to the list of experts on an article about climate change.

NOTE: I am no expert so I am not saying which side would be the deniers in this case! I just detect a logic error here. It appears we're running the risk of WP:SYNTH here if us editors decide where and how much weight we give each side.

So. First question: Is this a good source or not? CapnZapp (talk) 11:42, 31 July 2021 (UTC)

I think the main issue from this search is that it appears to be a minority view. The author has apparently published articles related to space law before, so I think it's appropriate to mention their viewpoint in that context but it shouldn't be discussed too much. Jo-Jo Eumerus (talk) 12:17, 31 July 2021 (UTC)
Mentioning their view point is one thing. Using it as a source to have our editorial voice claim things like Karman never attempted a line himself and was just the name Haley assigned to his own attempt is something entirely different. (That's just bickering about history, which I fully agree is a minor point all things considered, but it exemplifies the dangers about using a source that basically disagrees with everybody else) CapnZapp (talk) 12:30, 31 July 2021 (UTC)
The article is nice because it cites many other sources. News articles rarely do so. The conclusions are the authors conclusions but the story (facts) seem to be very well grounded in other sources. Also there are quotes from other people in the article which I think are also important. So this is a real scientific article. And from what I found the person writing it is not just some law student or whatever. He seem legit. Nux (talk) 20:33, 2 August 2021 (UTC)
Well, sure, but what you need in order to evaluate a source is mentions of that source in other sources. Especially when its opinions go directly against our other sources. Is Gangale's conclusions commonly accepted in the field? (Is his findings corroborated by even one other credible authority in the field?!) Otherwise it's just one fringe opinion... no matter how well-written or well-sourced it is, it can still be what we would call WP:SYNTH if Gangale had written it here on Wikipedia. (Note: I'm trying to explain why "citing many sources" or "quoting other people" isn't necessarily what makes a source good) Cheers CapnZapp (talk) 08:24, 3 August 2021 (UTC)
Gangale seems like an excellent source, but let's be careful that we correctly understand what he is and isn't saying. He does not dispute that the Karman line is generally defined as 100 km, and has no objections to that, as long as it's understood that the name was only chosen in honour of von Karman, not because von Karman himself came up with that number. He doesn't completely rule out that it was in fact von Karman himself who came up with the 100 km, but says that such a proposal is not mentioned in his published writings. His main concern is that the 100 km line (or any of the other values he mentions) should not be used as a legal definition of the boundary of space. He is not saying the Karman line should be renamed or given a different value. Martijn Meijering (talk) 09:51, 3 August 2021 (UTC)
I don't have a problem with mentioning Gangale's article, but if it's a minority view (which it seems to be), then it should be mentioned in that context. It shouldn't be the basis for substantive content if it's just part one person's justification for saying the Karman line is insignificant. Fcrary (talk) 18:34, 31 July 2021 (UTC)

FAA and NASA recognition of 50mi rather than 100km

Should the article list the FAA and NASA stating the boundary of space is 50mi or 100km?Garuda28 (talk) 00:22, 14 July 2021 (UTC)

@Nux: The source you added does not directly state that the FAA recognizes the 100km Karan line, instead stating that "Many people believe that in order to achieve spaceflight, a spacecraft must reach an altitude higher than 100 kilometers (62 miles) above sea level." The majority of RS state that the FAA utilized the same 50 miles used by the Air Force as defining the boundary between air and space and for awarding astronaut wings (https://www.washingtonpost.com/technology/2021/07/11/richard-branson-virgin-galactic-live-updates/; https://www.nationalgeographic.com/science/article/where-is-the-edge-of-space-and-what-is-the-karman-line; https://www.technologyreview.com/2019/06/26/238928/where-does-space-begin/; https://www.nbcnews.com/science/space/branson-virgin-galactic-space-launch-n1273547)

The FAA itself states to earn astronaut wings "Must demonstrate flight beyond 50 statute miles above the surface of the Earth as flight crew on an FAA licensed or permitted launch reentry vehicle." (https://www.faa.gov/news/fact_sheets/news_story.cfm?newsId=19074)

NASA also acknowledges this 50mi boundary in the majority of reliable sources (https://www.space.com/will-richard-branson-reach-space-virgin-galactic; https://www.cnet.com/news/blue-origin-and-jeff-bezos-get-faa-approval-for-july-20-trip-to-space/)

Do you have secondary sources that state that the FAA recognizes the Karman Line (100 km) rather than the 50 mi indicated by all these secondary sources?Garuda28 (talk) 00:22, 14 July 2021 (UTC)

I think that treating news articles as better sources is wrong for science articles. Most articles do not cite any sources so they might as well be copying from each other or from wiki ¯\_(ツ)_/¯... I guess the exception is nat-geo article which does cite some sources. Interestingly it says that for the purpose of astronaut wings NASA does conform to Air Force definition, but it also says "NASA Mission Control places the line at 76 miles (122 kilometers), because that is “the point at which atmospheric drag becomes noticeable,” Bhavya Lal and Emily Nightingale of the Science and Technology Policy Institute write in a 2014 review article." [3]. So I think saying that NASA agrees to 50 miles as space boundary is missleading.
I also find it weird that multiple people try to re-define what Karman line means. Not FAA nor NASA define Karman line differently. Karman line is a Karman line. A law journal with multiple references [4] clearly says that Karman line was defined as 100 km. It was named after Karman (not by Karman) and agreed upon by many countries. Most importantly by those actually going to space -- U.S. and Russia (then Soviet Union).
--Nux (talk) 01:24, 14 July 2021 (UTC)

Pdf pg14of27 of this 1964 tech paper explains that Free Molecular Flow happens at an altitude above “75-80 Km”:

https://apps.dtic.mil/sti/pdfs/AD0457278.pdf

The word ‘space’ essentially means a realm where the space between molecules has gotten very large. Free Molecular Flow means that the atoms move significant distances without bumping into each other. You can artificially create a realm of space in a vacuum chamber. Or if you fly high enough, space occurs naturally in the realm known as Outer Space. Stated more simply, the 100km threshold was picked arbitrarily. Whereas there is excellent rationale for using 50 miles (=80km =FreeMolecularFlow =Space). —Tdadamemd19 (talk) 03:24, 14 July 2021 (UTC)

Cool, but the article is about the Karman line... Well it is named Karman line, but seems to be more and more about random space related things. Nux (talk) 08:14, 14 July 2021 (UTC)

Hardly random. The point is that a specific transition happens above 50 miles (80 km). And that this fits with the very notion of what space is. A significant amount of space between the molecules. The Karman Line is all about arriving at a definition of where the transition to space has happened. The concept of free molecular flow goes a long way toward informing that threshold. —Tdadamemd19 (talk) 09:06, 14 July 2021 (UTC)
I'm still skeptical of whether this provides a relevant definition of the edge of space:
  • Do you know if any organisation or authority has ever proposed such a definition?
  • Doesn't the point of transition depend on the length scales involved? The paper is about small metal strips. I guess for something the size of a human or spaceship the transition would happen at a higher altitude.
--BlauerFuchs (talk) 20:15, 1 August 2021 (UTC)
Definitely. Free molecular flow happens when the mean free path of the molecules is ten or more times greater than the length of the object in question. So the larger the object is, the higher the altitude required for it to be in free molecular flow. Fcrary (talk) 21:29, 1 August 2021 (UTC)

Yeah but you cannot redefine what meter means. There is an international body that defined and named Karman line. You can discuss what space is not what Karman line is. Nux (talk) 10:04, 14 July 2021 (UTC)

Suggestion to delete Free molecular flow paragraph

In its current form, the paragraph about "free molecular flow" in the section about alternative definitions does not appear to have a concrete connection to the Karman Line. In particular, the part about "space between molecules" sounds rather esoteric and not very scientific.

In particular, closer study of the cited article reveals that the altitude (or density of the atmosphere) at which aerodynamics is best described by the equations of free molecular flow depends heavily on the size of the object in question. Therefore, the sentence " It has been known since at least as early as 1964 that the transition to free molecular flow happens at an altitude above “75-80 Km”" is not a correct citation (or at least is misleading) IMO.

Certainly, the concept of "free molecular flow" is not widely accepted to be "A key consideration" with respect to the Karman line as the first sentence of that paragraph suggests.

In summary, I suggest to delete the paragraph in its current form, since it does not represent scientific consensus. (talk) 16:45, 30 August 2021 (UTC)

Good point. Whilst free molecular flow occurs naturally in outer space, that does not figure into the variegated factors which define the Kármán line. As a practical matter outer space begins where aerodynamics ends, and as just as practical a matter orbital mechanics would hold sway some distance beyond that– it's not as if the line is only several meters thick! It's a liminal space. kencf0618 (talk) 13:38, 22 June 2022 (UTC)
  1. ^ Isidoro Martinez http://webserver.dmt.upm.es/~isidoro/tc3/Space%20environment.pdf
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