Talk:Gravitational keyhole

Speedy Deletion

Wait- I know it's just a crappy stub right now, and needs love, but this was a red link that I thought deserved at least a stub for now. (Frankly, I'll never understand why an article that has links to it would get elected for deletion, but, then, I'm an inclusionist...) - This is a genuine term used in scientific articles to refer to a physical phenomena - why delete it? Eric 09:27, 31 October 2007 (UTC)

Another thing - a quick Google search reveals that this term has been used by NASA, CNN, Popular Mechanics, KNOX-TV News, and Cosmos Magazine, among others. - Eric 09:37, 31 October 2007 (UTC)

User:Realkyhick is quick on the delete tags, just look at his history. The way to get around that is when you start an article, make sure there's at least one or two sentences, one citation, an external links or references section listing the same citation as you did in the article, and you're good to go. Make one edit to the article, put the "stub" tag on it, and most db-taggers will leave you alone. Mindraker 21:11, 7 November 2007 (UTC)

Little Boy reference

Why is a reference to the Little Boy bomb required under the Torino Scale section? Surely the article linked to before the note is sufficient without asking the reader to perform mental arithmetic? --Rfsmit (talk) 20:11, 4 August 2008 (UTC)

Really doesn't make sense, and disagrees with the linked article: the Megaton article lists the energy as 15 (fifteen) kt, not 13 as in this article's note; while the Little Boy article uses a range: "It exploded with a destructive power equivalent to between 13 and 16 kilotons of TNT (estimates vary) [...]". Because of the inappropriateness and the lack of agreement, this note was deleted.--Rfsmit (talk) 21:09, 4 August 2008 (UTC)

Etymology

I'd like to see someone providing the origin of the term. It would appear to refer to the keyhole-like shape of the volume of influence; but the reference could be more vague, i.e. an object passing through a region of space "like a key into a keyhole"; or it could be even more vague, i.e. "this event unlocks a future event" (akin to a computer gaming term). --Rfsmit (talk) 20:52, 4 August 2008 (UTC)

• (Sorry for replying to my own post.) Yahoo! Answers: "(It's called a keyhole because it's a very small region of space.)" This would appear to be the correct interpretation, a contrast between the vastness of space and the relatively tiny region through which a body might pass. --Rfsmit (talk) 20:57, 4 August 2008 (UTC)

Pictures

I would like to see a picture. Do keyholes appear to be arbitrarily placed? Also, are keyholes the best spots to attempt an orbit change? Or are keyholes merely good locations to accurately calculate future orbits? E.g., it may be easier to monitor a ~400 meterish region close to earth even though there might be a larger keyhole much farther away. —Preceding unsigned comment added by 131.252.223.59 (talk) 13:42, 26 August 2008 (UTC)

• Diagram would be more accurate. The keyhole is not a special region of space by itself; infact I think the term is misleading. Gravity in the keyhole is still uniform.
• Apophis is not currently on an collision path with Earth in 2029 or 2037. In 2029 the close approach to earth will change its orbit. The about depends on the parameters of its close approach (distance, angles). To achieve an impact in 2037 the parameters must all be within specific ranges. These ranges can be most easily visualised as a surface (keyhole) in space. 203.26.11.62 (talk) 01:40, 9 November 2009 (UTC)

Where exactly the Keyhole is depends on the orbit/trajectory of the object. So for different objects, the Keyholes have different size, shape and location. And yes, these would be the perfect places to change an orbit, lowest energy requirement. If you have the orbit of an object and add a little bit of uncertainty and make a diagram of all possibilities in space, you have something like a ribbon or a tube going through space, getting larger as you go further away from the object. (A close flyby of another massive object will greatly increase that uncertainty, after the flyby the tube will be spreading outwards at a larger angle). If that tube hits earth, you calculate in the opposite direction, and you will get a much smaller tube that is always surrounded by your original bigger tube, and it will get smaller as you get closer to the object. Keyholes then are these locations where the rate of change in the circumference of the tube is biggest, keyholes will always be right in the middle of a close encounter with another object. The article http://en.wikipedia.org/wiki/Interplanetary_Transport_Network has a nice image that helps to visualize it, and adds some helpful background. Maybe we could use that image here, but i think we might need a more fitting one. 188.104.102.52 (talk) 15:10, 7 November 2011 (UTC)

99942 Apophis

I came to this entry linked from the 99942 Apophis main page and found the information in the Apophis section to be incorrect... It was listed as a 1 in 50 chance of striking the earth in 2029 as opposed to the current estimate listed on the main 99942 Apophis page and later in the section as 1 in 45,000. As the first and fourth paragraphs are somewhat redundant, it seems to me that the section could use some cleanup. Vargob (talk) 17:45, 19 March 2009 (UTC)

Done. --Rainald62 (talk) 12:33, 25 September 2012 (UTC)

a tiny region of relevance in the vast space of Wikipedia

As a reader, I'd like the article better if it had even one sentence about the nature of a keyhole. Is there something special about the curvature of that bit of spacetime? Or is it merely the intersection of the cone of possible danger paths with the time of perigee in 2029 (since small differences are magnified at perigee)?

Most of this article, as it now stands, belongs elsewhere. —Tamfang (talk) 19:51, 23 December 2009 (UTC)

Is Interplanetary Transport Network related? —Tamfang (talk) 19:58, 23 December 2009 (UTC)

I agree with Tamfang. This article does nothing to tell me anything about the nature of a gravitational keyhole. It is about a particular asteroid. 206.8.2.154 (talk) 16:01, 4 March 2011 (UTC)

Yes, the Interplanetary Transport Network also has images of catchment areas, but those close to Lagrangian points are not as tiny as the ones close to planets. If the term "gravitational keyhole" is used in the context of the network, the link to the network may be integrated in the main text. However, I don't think so: There are thousands of Google hits for

     "Interplanetary Transport Network"|" keyhole

but only five for

     "Interplanetary Transport Network" keyhole -wikipedia -"region of space where"

There are two Google-books hits for

     "Interplanetary Transport Network" keyhole

but none for

     "Interplanetary Transport Network" keyhole -wikipedia

There is no Google-Scholar hit and the only Scirus hit is a copy from Wikipedia. Similar results are obtained with "Low energy transfer" --Rainald62 (talk) 12:33, 25 September 2012 (UTC)

WHAT IS A GRAVITATIONAL KEYHOLE?????

WELL WHAT IS IT? Has this article explained anything at all? The mechanics or physics of what a gravitational keyhole actually is or how it arises in terms of gravity and science? This is ridiculous. —Preceding unsigned comment added by 81.141.147.41 (talk) 13:41, 12 February 2011 (UTC)

I agree and have written and added a new section to the article, titled "Explanation," to clarify the concept. Feel free to improve Jedwards01 (talk) 06:55, 23 April 2011 (UTC)

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