Talk:Asteroid impact avoidance/Archive 1

Links
Some of the links, that I found, perhaps ought to be moved from this article on deflection strategies, to one of the related articles, that focus more on what the problems are that call for deflection strategies. User:AlMac|(talk) 02:38, 23 January 2006 (UTC)

There needs to be a disambigous page for the asteroid named Apophis that will graze planet Earth in 2029. User:AlMac|(talk) 06:29, 23 January 2006 (UTC)

Separate sections or main articles
I think there may need to be User:AlMac|(talk) 07:49, 23 January 2006 (UTC)
 * 1) Separate article on this topic in Science Fiction.
 * 2) Separate article on the public relations angle of
 * 3) Each time one of these is discovered, the news media cries "wolf" making it sound like the scientists do not know what they talking about.  Then as the scientists get more and more info, getting better and better estimates, and the news media reports this, it sounds like they did not get it right the first time.
 * 4) By the time the human race is really threatened, the voting public will be so used to each news story being worse than the last story, then turning out to be nothing, that we humans will not take the real thing seriously.
 * 5) There are also political issues.  Suppose an effort by nation-A to deflect fails, and nation-B gets hit.  Assuming nation-B survives, what kind of liability is nation-A facing?
 * 6) We have various strategies proposed.  What we do not have are the major pros and cons of each strategy.  For which of them does the technology exist?  What kind of expense?
 * 7) I saw that Carl Sagan had said that developing some of these strategies was potentially more dangerous than the threat they protecting against.  Can we get the specific quote?
 * 8) Are there other efforts in space which, if perfected in time, can also help with the flexibility of solving this one?
 * 9) For example space elevators could make it more inexpensive to get the anti-asteroid weapons and fuel to escape earth orbit.
 * 10) Time Line{s) ... there may already be relevant wiki articles ... if so need to link with this, if not perhaps need to add some
 * 11) Significant historical impacts when, sequenced not chronologically but from greatest damage or potential threat, to less of a risk of harm.  We can then see clearly how often planet Earth is placed at risk by impacts of various severity.
 * 12) Indicate how much damage they would have inflicted had they arrived in a major city, rural area, ocean strike, other terrain.
 * 13) Number of Near Earth Objects of comparable or larger size, and frequency with which they cross Earth orbit, so we can see the rate at which we are playing this cosmic Russian roulette.
 * 14) Human understanding has dramatically evolved in a relatively short time span.  When I was in college in the 1960's there was a cover story in an Analog Science Fiction and Fact magazine on Giant Meteor Impact which identified scars on surface of planet Earth from prior impacts and compared their energy signature with major volcanic eruptions, such as Krakatoa.  An ocean strike was considered worse than a land strike because of risk of penetrating the magma on ocean floor and punching a hole in the planet's crsst, with a super volcano coming back out of it, triggering the mother of all tsunamis.  In the 1960's the whole idea of extinction impact was science fiction to most people, even though the race to the moon was on, and anyone who looks at the moon can see that it has been plastered, the idea that the Earth had also been plastered, was just not what a lot of people willing to believe.
 * 15) Do we really know if the risk is about the same over time?  As global warming contributes to sea level rise, human habitation becomes more at risk to risk of damage from giant tsunamis.
 * 16) Spaceguard existed on a volunteer basis around the world long before US Congress gudgeted funds, after many years of ignoring USAF budget requests for planetary defense.  Other nations, equally slow to respond to their relevant experts requests.

Panic Now!
This could be an interesting article, full of pros and cons of existing or near-future technology plus speculative solutions. But unfortunately, a good portion of the article is already littered with sensationalistic "it could happen tomorrow!" kind of fear mongering. Perhaps, according to someone's math, it is more likely to be killed by a falling asteroid than die in a plane crash, but they both still have a very, very low probability. So comparing them is somewhat silly. (IMHO) I think we should reduce the "likelihood of an impact" and "effects of an impact" topics no more than one paragraph each and spend most of the article dealing with the stated topic. –Shoaler (talk) 19:52, 24 January 2006 (UTC)


 * I plead guilty to adding content to show that there is a definite risk out there, against which the planet needs to defend itself. I feel that such content belongs someplace in Wikipedia, but perhaps in other articles.  I do not have a good feel for all the related articles that do exist, where the timeline may belong, and was contemplating other main article(s) where some detail could subsequently be transferred to. User:AlMac|(talk) 12:38, 25 January 2006 (UTC)

Trampoline
Nice try, anonymous :) Please put it back in iff you find a source... University of Queensland devised a plan utilising advanced polymer technology in 2005. The polymer-metal compound produced is engineered into several giant tensile springs, each approx 1km in length. They are then assembled to a trampoline megastructure designed to bounce the incoming comet back out to space upon impact. Some speacialists suggest having several people simultaneously jumping on the surface of the structure could help to "super-bounce" the comet with even greater force. --DerHerrMigo 14:40, 2 February 2006 (UTC)

Yet another bogus strategy
I may be over-zealous this time, but I can't quite believe this would work: '' Creating an artificial debris cloud in the object's path so that upon impact the object will be deflected. '' You'd need one helluva lot of debris - where do you take that from? --DerHerrMigo 20:23, 3 February 2006 (UTC)
 * I tend to agree with you. As phrased, that won't work.  A debris field sounds like a rubble pile, which can cause same kind of damage.

User:AlMac|(talk) 10:50, 4 February 2006 (UTC)
 * The gravity tractor idea does not need a regular space craft, but it does need propulsion attached to the gravity source.
 * Another asteroid, captured, attach space drive, then use that a number of ways, depending on how good precision of aiming. It is like shooting a bullet with a bullet. Can we do that with ABM technology, or does that really mess up the electronics of incoming missiles, and not truly have bullet hit bullet.

What about comets?
They pose a threat too. Perhaps this article needs to be moved to Meteor deflection strategies? --Revolución (talk) 03:39, 29 January 2006 (UTC)
 * Actually, the sad fact is that most experts think comet impacts are essentially unpreventable, because their orbits would generally give almost no warning beforehand. You know, that should probably be in the article...--Pharos 19:07, 4 February 2006 (UTC)

Nice new article & nice new strategy
http://www.popsci.com/popsci/aviationspace/da8309cdd1919010vgnvcm1000004eecbccdrcrd.html Could someone update wiki? The main idea is using gravitational force. They claim that it would be possible to slightly change trajectory of 50 million tons asteroid named 99942 Apophis(1 to 10000 chance to hit an Earth in 2036), if they could sent spacecraft by year 2029... They mention Russian Federal Space Agency; U.N. Office for Outer Space Affairs; JSR Space Report, article looks serious.  TestPilot  06:07, 10 February 2006 (UTC)


 * I added this theory some time ago, with multiple links to show it was a valid theory from notable people, but other volunteers here kept deleting that material without good explanation. I not want to get in an edit war, so I leave it to consensus what belongs. User:AlMac|(talk) 05:08, 11 February 2006 (UTC)


 * Hmm...  TestPilot  07:55, 11 February 2006 (UTC)
 * I reinstalled that paragraph. I checked history - first it is not a volunteers, just one anonym. Looks like he simply do not understanding idea and do not believe in that strategy. And do not bother to check sources. And, now I noticed that Gravity Proposal was mentioned here(discussion page), and there was no need to create new section - totally mine fault.  TestPilot  08:28, 11 February 2006 (UTC)


 * Hey guys - I'm glad you put that back in! I've reworded the section quite a bit, making it (hopefully) easier to understand; hope you like it. It could still use some 'polishing' by a native speaker, though... --DerHerrMigo 18:00, 11 February 2006 (UTC)
 * Yeah, thanx. I absolutely love your edit - it way more understandable now.  TestPilot  20:34, 11 February 2006 (UTC)

Terminology
The word program is used on more than one occasion in this article. To assist people whose first language might not be English I propose that program be used to descibe a computer program, and programme be used to describe a series of events. Arcturus 12:11, 12 February 2006 (UTC)


 * The word program existed long before computer programs came along, and with the rise of computers, continued to be used quite heavily in many contexts unrelated to computers, such as


 * government program
 * project program
 * convention or conference program
 * Perhaps it would be more relevant to ask about spelling in different English speaking nations. I think programme is British while  program is American, but how is it done in Australia, India, and elsewhere, particularly the nations that have active space programs (or is that space programmes?), and thus likely to have constructive contributions to this subject. User:AlMac|(talk) 10:34, 14 February 2006 (UTC)


 * Yes, it might boil down to different versions of English. Here in England, the usage is as I described, with program always being used to refer to a computer program. Therefore it's quite easy to understand the context (it's easy anyway for native English speakers, of course). I think in America programme is not generally used in any context. However, maybe we should think about the alternative spellings as a way of differentiating the usages. Arcturus 17:20, 14 February 2006 (UTC)
 * English is a second language for me. And I have never before saw(noticed?) use of programme word. Program is way more popular - Google give 5,050,000,000 results vs 560,000,000 for programme and more understandable. Lets keep it simple. But i live in Canada, so i got "chequing account" in my bank and I live not far from "Chinatown centre". So there is some differences.  TestPilot  05:23, 15 February 2006 (UTC)

Political dangers?
Referring to this paragraph from the article:

“The dangers posed by such collisions go beyond the physical destruction caused by the impacts themselves. A nation hit by less than extinction-destructive force may, depending on their military political situation, think they are being attacked by another nation and retaliate. If this had happened to a superpower during the Cold War, it may have thought it was under nuclear attack and "returned" fire.”

I think this paragraph/rambling should be deleted: it reads like someone thinking out loud, and makes little sense. A nation hit by a massive asteroid impact will not confuse it with a nuclear attack due to, among other things, the singularity of the impact (as opposed to several smaller warheads), the lack of radioactivity, the lack of any detectable delivery methods (no planes or missiles), the magnitude of the explosion, and the knowledge, even if gained only a few hours prior to the impact, that an asteroid impact is imminent. This adds no value to the article.

Ron g 16:54, 24 July 2006 (UTC)

be bold!
and fix it ! ;>Xenocidic 16:15, 31 July 2006 (UTC)

2 edits
1. The 'social problems' aspect appeared quite biased as holding the whole endeavour as a waste of funds. Gramatically, it was quite rambling as well. I believe I remedied both. I would prefer to make more sweeping changes, but I do see the utility of the viewpoint.

2. I added a portion to mitigate against the view that our detection strategies are (or soon will be) 100% efficient. At the very least, asteroids can have an approach plane which keeps them blocked by the glare of the sun, and that leaves them currently undetectable.

The 1972 Near Impact Event
Not disputing it, but I'd imagine something of this significance would be easier to obtain sources for. Anyone got anything more concrete?
 * See and its references. The event did occur, but the size quoted in the article is exaggerated. The above web site refers to size estimates from 3 to 80 m in diameter, with impact energies (had the object hit straight on) being "Hiroshima-sized" at the lower end of that size range. --mglg(talk) 22:31, 5 January 2007 (UTC)

Project Icarus
I changed 'Icarus Project' to 'Project Icarus' which is the actual name of the book. Someone probably wants to create a page for it - there are good details here http://www.thespacereview.com/article/175/1

Does anyone mention?
Does anyone think that a nuclear explosion, but a miscalculated one, will send smaller radioactive asteroid pieces to Earth instead? Should this be adressed as a "con" for nuking the asteroid? Brandonrush 22:39, 13 March 2007 (UTC)

fiction overlap
The subsection "fiction" on this page overlaps with, but is less exhaustive than, the fiction section in Asteroids in fiction (Asteroids in fiction). Should these be condensed to a single article on asteroids colliding with Earth in fiction, instead of two? Geoffrey.landis 20:43, 4 October 2007 (UTC)

Fair use rationale for Image:Deep Impact poster.jpg
Image:Deep Impact poster.jpg is being used on this article. I notice the image page specifies that the image is being used under fair use but there is no explanation or rationale as to why its use in this Wikipedia article constitutes fair use. In addition to the boilerplate fair use template, you must also write out on the image description page a specific explanation or rationale for why using this image in each article is consistent with fair use.

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BetacommandBot (talk) 21:09, 13 February 2008 (UTC)

Anti-nuclear bias
The anti-nuclear tilt is too obvious. Maybe some Wiki-ist can resist beating the anti war drum.

"Nuclear scientists are simply trying to find new excuses to keep nuclear missiles around"

Its only the most powerful force creatable by man. I'm not sure they can make millions of tons high explosives much less get it into space.


 * Totally agree. These wimpy methods of placing vapor cloud in the path of an asteriod and the like are ridiculous. It's an ASTEROID for crying out loud! We are talking about cubic miles of rock here! For computationally challenged I translate - a cubic mile of rock (or even ice) weighs BILLIONS of tons.


 * Nice megaton-class surface or slightly above surface thermonuclear blast - that's the stuff which works. And by the way, it works not by "shattering the asteroid to pieces", but by vaporising and venting a lot of surface material, creating a rocket exhaust effect.


 * Again, for the computationally challenged - 1 ton thermonuclear device delivers ~6 MT blast. Delivery of such device to the asteroid is quite doable with todays launch vehicles. Deep Impact mission's impactor weighted 600 kg. —Preceding unsigned comment added by 89.102.207.196 (talk) 21:16, 9 June 2008 (UTC)

More ideas
Anyone who has read any science fiction (like me) knows about lots of other things that in theory could be done, that does not seem to be part of the near future science consideration. Would it make sense to have a "main artlce" on how this is solved in the world of Science Fiction. There is a Time travel article which reads like science thinks that is plausible, with a main article Time travel in fiction.

Examples of what I mean by solutions in Science Fiction: User:AlMac|(talk) 06:30, 30 December 2005 (UTC)
 * Stick eyes in the sky to see the menace long before it gets here, like a satelite on the dark side of the moon, in the equivalent of a 24 hour orbit over planet Earth where satelite in fixed point in sky. So these satelites are used to map what's coming at us from all directions, and where the risks might be, instead of risk not find out about the thing before it is right on top of us.
 * Spend serious money budget to send expeditions to some of those asteroids and comets that cross earth orbit, to learn as much as we can about their composition, what it would take to divert them. We need to know as much about them, if not more, than we know about all other bodies in the solar system other than the Earth and the Sun.
 * Send an expedition to the Asteroid belt, and tow some of them back here, to use as shields ... a big rock is hurtling towards us, so we take one of the shields and acelerate it up to rammming speed, at a collision angle that will take the debris away from Earth.
 * There are some SF movies that involve shooting nuclear missiles at these rocks. I would like to see some scientific analysis of the validity of the "science" in those movies.  If we tried that in real life, I expect that instead of a huge rock on a collision course with Earth, there would be a huge radioactive rock on a collision course with Earth.


 * Just beautiful. You think it's plausible to "tow some" asteroids here and then "acelerate it up to rammming speed, at a collision angle" (reality check - do you have a slightest idea how much asteroids weigh??) but at the same time you think deflecting an asteroid with surface nuclear blast(s) is not? I propose you first study in depth how many letters "c" should be in the word "accelerate". —Preceding unsigned comment added by 89.102.207.196 (talk) 21:24, 9 June 2008 (UTC)

What about landing thrusters on it and using them to force the thing away (preferably into Jupiter or the sun, where it won't come back). —The preceding unsigned comment was added by 211.30.132.2 (talk • contribs).
 * Hmm...with that last one- if the explosion was forceful enough, you could knock it out of its path. I'm not a scientist myself, but I have seen stuff on this. One concern is that the structure of some asteroids would absorb a lot of the blast. —The preceding unsigned comment was added by 211.30.132.2 (talk • contribs).


 * You'll have to explain what you mean by "absorbing the explosion." So long as the blast hits the asteroid, conservation of momentum is unavoidable, but I guess it's possbile some might break off little pieces, and then we have a lot of little asteroids headed for the Earth.  Well, getting hit with buckshot is probably better than getting hit with a tank shell, but getting hit by buckshot followed by a tank shell would probably be even more unpleasant.  Someguy1221 08:40, 11 June 2007 (UTC)


 * "Absorbing the explosion" means that its structure will sort of crumple- but the blast won't actually stop it from moving towards us. It's sort of like punshing a really huge sponge- you can hit it all you like, it won't move.


 * Here is a bit of "sort of mathematics" for you. Let's say we build, send and blow up a 2 ton thermonuclear device on the surface of the asteroid. It delivers 12 MT blast. Such blast creates 4 sq.km. by 50 m crater on Earth, in other words, it ejects 200 000 000 cubic meters of material. Let's assume 1 ton/cubic meter density (water ice). Let's assume that average speed of ejecta is 1 km/s. The total impulse of so much material leaving the asteroid is 200 000 000 m^3 * 1000 kg/m^3 * 1000 m/s = 200 000 billion kg * m/s. For 6 kilometer wide water ice asteroid (mass approx 200 000 000 000 000 kg) it changes its velocity by 1 m/s. Even if my assumptions (density, amount and speed of ejecta) are seriously off, such nuke should be enough to deflect kilometer-sized objects.


 * If we have lots and lots of little asteroids, it might not be too bad- if they were small enough, they'd burn up in the atmosphere. You'd need to be careful that they don't smash into satellites. You coudl break it up, but personally I'd rather redirect it somewhere away from Earth. In the worst case scenario (if it was really clsoe to Earth), I'd send it flying towards the moon. It's protected us form asteroids before (though not flawlessly).


 * Your analysis of "absorbing the explosion" doesn't work, see conservation of momentum. Punch a sponge in the vacuum of space, it'll move.  Though this is more accurately compared to throwing something at the sponge.  Someguy1221 06:34, 28 June 2007 (UTC)

BTW, who was it that said that wed need ten years to prepare for a 200 m asteroid? That's ridiculous: as soon as it became apparent a 200m rock was heading our way, I reckon a few people might try and do soemthing about it.

Some here malign the gravitational tractor idea because of a perceived anti-nuke bias; however, the case for such a strategy (namely, the ability to affect 'awkward' asteroids with high spin or considerable debris clouds) seems valid. However, the gravitational force is the weakest of the fundamental forces; perhaps this deflection method could be augmented by the addition of an electron-gun/accelerator on the tractor, such that the electrostatic force could be added to the gravitational force in the tractor. I've not done even preliminary calculations on this, though, so I don't know if it could produce a usable effect.

Asteroid Gravitational tractor
- NASA astronauts Edward Lu and Stanley Love have proposed using a large heavy unmanned spacecraft to pull an asteroid into a non-threatening orbit. Here's one article about their proposal. The craft was originally designed for another mission, uses electric thrusters, using electric power to heat a gas to extremely high temperatures and squirt jets to the sides of the asteroid, not directly at it, which would undermine the desired gravity tug boat effect, maintaining a constant close distance so gravity can do its work. By using gravity to pull the asteroid, this can save us from near earth objects that have the consistency of piles of rubble, which if detonated just changes distribution of the rubble still headed towards us, or high rotation that is difficult to mount a pusher on. The gravity tractor would have to spend approximately a year beside the asteroid to be effective.


 * Dawn: ~1 ton, total dV 11000m/s (achieved in 2000 days of thrusting). If we impart the same impulse onto 1 cubic km asteroid with density 1 ton/m^3 (density of water) by making Dawn-like spacecraft to hover upon it as described, velocity change will be something like 0.000011 m/s, or 0.011 mm/s. This is after ~5.5 years of "gravity tracting". Give me a break. 89.103.91.47 (talk) 17:14, 22 June 2008 (UTC)

I had originally started this writeup, then added to it, since I felt it was a notable effort by NASA scientists, reported in believable media, that was different from the write-ups that I found in the other solution strategies. User:AlMac|(talk) 00:26, 25 January 2006 (UTC)

Thanks, I see that someone has put the section back in, and phrased it much more elegantly than I had, but dropped the citations proving that the content is truth. User:AlMac|(talk) 12:33, 25 January 2006 (UTC)

Gravitational Tractor
- Proposed by NASA scientists Edward Lu and Stanley Love, this plan calls for a huge, ~20 ton spaceship to hover near the asteroid, years before it comes close to hitting Earth. With the heavy end of the spaceship facing the asteriod, this should be enough to "pull" the asteriod into a slightly different orbit, that years later will save earth.


 * This more elegant write up, without the earlier citations and additional detail, was also removed. I hope it was removed for improved re-write. User:AlMac|(talk) 01:13, 29 January 2006 (UTC)


 * As I commented above, the idea is ridiculous and is probably born out of irrational fear of using nuclear bombs for quick and efficient asteroid deflection. 89.103.91.47 (talk) 17:18, 22 June 2008 (UTC)

What do you think?
In the section "Poplular strategies" it says "Destruction concentrates on rendering the impactor harmless by fragmenting it and scattering the fragments so that they miss the Earth or burn up in the atmosphere. As will be shown, this does not always solve the problem, as sufficient amounts of material hitting the Earth at high speed can be devastating even if they are not collected together in a single body." It never dose explain that and I was wondering if we should explain why it makes the problem a hundred times worse. Skeletor 0 (talk) 16:35, 5 September 2008 (UTC)

Typical glitches
this article:

there is a slim chance that during the 2029 close encounter with Earth 99942 Apophis will pass through a "gravitational keyhole"  approximately 400 m across,

99942_Apophis article:

a possibility remains that during the 2029 close encounter with Earth, Apophis will pass through a gravitational keyhole, a precise region in space no more than about 600 meters across,

tip: do not use precise numbers if you just don't really know :P

It is now anticipated that by year 2008,' 90% of such objects that are 1 km or more in diameter will have been identified and will be monitored

no offence but it is 2010 now. Quite a lot of data here is already a bit old. Egh0st (talk) 18:12, 1 January 2010 (UTC)

Practicalities
In Bill Bryson's 2003 book A Short History of Nearly Everything, he says people assume we would blast an approaching asteroid with a nuclear missile, but he points out out missiles are not designed to leave the atmosphere and if they were we have no mechanisms to guide them across space; as for sending any humans up there to do something, we no longer even have any rockets powerful enough even to go to the moon. Meanwhile, he quotes Ray Anderson of the University of Iowa, a geologist with expertise in meteorite impacts, who says it is quite possible no one would even notice a large asteroid coming until it started to enter the atmosphere and heated up. It is quite possible no astronomer would have been looking at the right bit of sky to see it coming soon enough for us to try to do anything about it. Should these sort of problems be mentioned more in the article, do you think? 88.165.185.189 (talk) 16:29, 23 January 2010 (UTC)

Impacts without warning?
Are impacts of considerably large asteroids (let's say Tunguska equivalent and larger) without warning still possible? And given a 1-mile (1.6 km) previously unknown asteroid (or dead comet without coma and tail) heading towards Earth - at which time will it be most probably be detected by existing (2010) techniques, if it approaches a) from the night side (i.e. fully illuminated, and within the observational sky area of optical telescopes), and b) from the direction of the Sun (+/- about 30 degrees, so that no easy detection from ground telecopes is possible)?

The article mainly treats the search for unknown asteroids and subsequent determination of its orbit, with respect to possible collisions with the Earth. However, as already mentioned for comets, there may still be the case of an asteroid or dead comet on an eccentric orbit (i.e. it is in the outer Solar System most of the time) that remains undiscovered until its final orbit that ends with an impact. Still it may be expected that there will be at least a warning of several years or months if the body is randomly detected. The question, for which I could not find a clear answer in the web, is: At which time or distance from Earth will the asteroid probably be detected (let's say in more than 50% of cases)? Is an 'impact without warning' scenario still reasonable even for global events (>1 km diameter)?--SiriusB (talk) 14:06, 28 July 2010 (UTC)


 * Given that the Tunguska event was caused by a small object less than 100 meters in diameter, a small undetected asteroid impacting during the day under the cover of the blinding Sun is very possible. A non-periodic comet headed towards the Earth would likely be detected by the time it was about as far way as Jupiter (5AU from the Sun). But keep in mind a comet less than 0.5km in diameter would take longer to become active and would be a harder target to find. -- Kheider (talk) 14:50, 28 July 2010 (UTC)


 * Hmm, I don't think that one can take the Tunguska Event as an example here. Even if we neglect the existing doubts about its cosmic origin there was nothing like the Spaceguard program active that time, nor was an impact even being discussed as a threat. Even if it hat approached from the night side it would have not been noticed if it was a stony asteroid without and coma & tail. And a 1-2 km body has a 100 times larger surface and thus is 5 magnitudes brighter than a Tungsuka-equivalent body. I am not talking about active comets here but about bodies without and coma and tail, e.g. scattered asteroids or dead comets. Are there any radar surveys that might detect an approaching body? What is the typical radar detection range if scanning the sky for any yet unknown approaching body (not to be mistaken with radar observations of known bodies to get their accurate position and velocity)? As far as I know it is possible to detect man-made space debris down to centimetre scale at LEO or at lest to metre scale at 36000 km this way. If we assume that the reflection of a 10cm body at 36000 km is just sufficient to be detected by a random survey, this means that a 1-km body could be detected at up to 3.6 Mio km (since both the angular cross-section and the radar beam intensity drop with 1/r^2) — this would allow only a couple of days warning time...--SiriusB (talk) 09:18, 2 August 2010 (UTC)


 * An object like 2008 TC3 or the astronomically small Tunguska Event may or may not be detected. Since current surveys do not cover the whole sky in a single night, if a telescope is not pointed in the direction that a small ~50 meter impactor is coming from, it simply will not be detected before impact.  Both of these impactors were to small to be detected by surveys when they were far from the Earth.  I believe radar is too focused to be used as a early warning system since optical telescopes can scan much larger regions resulting in faster detection. -- Kheider (talk) 16:01, 2 August 2010 (UTC)


 * Sounds plausible. However, what about 1 to 2 kilometre-sized bodies? Even those should be overlooked if nobody's looking at them, and such a body will be invisible to the naked eye beyond about 1 million km of distance even if fully illuminated. Or are there low-resolution whole-sky observations which would detect a +6 or +8 mag object within a couple of days? Even those should fail if a previously unknown body would approach from the direction of the sun (i.e. on an eccentric orbit which, shortly before the collision, has about the same tangential but different radial velocity component.--SiriusB (talk) 11:01, 23 August 2010 (UTC)

Asteroid scares
I'd like to add a section on Asteroid scares, such as the XF11 asteroid scare of 1998. As I recall the incident, an astronomer announced to the press, rather than keeping it among his colleagues, that in 2028 an asteroid might hit the earth, "destroying human life as we know it". It made headlines for a couple of days, and many people went to see a couple of asteroid disaster movies like "Deep Impact". --Uncle Ed (talk) 15:41, 11 January 2011 (UTC)

Source issues

 * Checklinks Viriditas (talk) 09:41, 2 May 2011 (UTC)

new section asteroid catching
for geo or lagrange pt storage http://iaf.marisdev.com/iac/archive/browse/IAC-05/D1/1/2189/ (no better link sorry) ?--Beaucouplusneutre (talk) 09:51, 11 July 2011 (UTC)

Ion Beam shepherd
I am not sure if this is included but I believe it should be included as a prototype defense device.

http://en.wikipedia.org/wiki/Ion_Beam_Shepherd — Preceding unsigned comment added by 98.114.231.244 (talk) 22:11, 11 April 2012 (UTC)

Deep Impact based on Arthur C. Clarke novel Hammer of God?
Only very, very loosely. If at all. See The Hammer of God and Deep Impact (film) --Dmtipper 17:56, 6 May 2006 (UTC)

Another book: Thunderstrike by Michael McCollum?
The threatening object is a comet rather than an asteroid which is why I'm not sure whether it belongs here or not. Loren Pechtel (talk) 03:12, 19 June 2012 (UTC)


 * A comet is observationally a different object than an asteroid, so it probably should not be added. -- Kheider (talk) 03:37, 19 June 2012 (UTC)

Spaceguard merge proposal
I received this comment from User:Power.corrupts in response to my proposal to merge Spaceguard into this article; might be worth pondering. -- Beland (talk) 07:54, 2 March 2010 (UTC)
 * Yes, I oppose. There is some overlap, mostly because Asteroid mitigation strategies is a large messy affair. I believe that we have enough info to have articles on detection and consideration about avoidance (your recent retitle to Asteroid impact avoidance is clearly an improvement). More to the point, there is enough 3rd party coverage, and enough potential, to justify a separate article on Spaceguard. On a general note, many merge efforts lead to massive clumsy articles, difficult to maintain, and worse, difficult to read to the average hurried reader who has a specific information need.  Try to figure out what a Lancet arch is, for instance.  I would suggest splitting Asteroid impact avoidance up into sub-articles, leaving it at as an overview main-article, directing the reader to other relevant articles.

Oppose: I agree that Spaceguard is notable enough to expand and keep as a separate article. If no one else comments in about a week, I will remove the merge tag. -- Kheider (talk) 15:47, 16 June 2012 (UTC)

I have removed the merge tag as oppose seems to be consensus and this discussion is months old.  —Entropy (T/C) 21:44, 1 December 2012 (UTC)

Popular strategies
Per WP:OR, theories should be published to be included here. A link to a researcher's personal homepage isn't a sufficient citation.

Also can someone clarify this sentence:
 * If not completely vaporized, the resulting reduction of mass from the blast combined with the radiation blast could produce positive results.

&mdash;Kymacpherson 13:31, 15 April 2007 (UTC)


 * Having a less massive asteroid hit the Earth would most certainly be positive, but I have no idea what good a radiation blast does, besides possibly putting us out of our misery when we're not expecting it ;-)  Someguy1221 08:43, 11 June 2007 (UTC)

+++ Oberth/Tsiolkovsky/Goddard meet Faraday/Henry/Weber/Maxwell ++ Electro-magnetic Field Reaction Propulsion and Electro-dynamic Induction Braking in Space Applications. – By Mark J. Carter Space propulsion has changed little since mankind took its first tentative steps into space. Even with the incremental advances in the efficiency of chemical fuels; the basic nature of rocketry is still defined by the basic Delta V Rocket Equation with all its limitations; be it the powerful boosters used to obtain orbital velocity or the low impulse Ion Thrusters used to power deep space missions. This ancient approach to propulsion limits both the potential flight parameters of deep space missions and the life span of earth orbiting satellites.

In earth orbiting satellites, the electronics of the satellite may last indefinitely; but the useable lifespan of that satellite is limited by the availability of on-board propellants used for orbital maintenance. Once the chemical propellant is exhausted, the satellite no longer has the capability of maintaining proper station.

The International Space Station is dependent upon chemical propellants to offset orbital decay. The need and use of these chemical propellants increases the potential for catastrophic accident, increases the cost of operational maintenance, and requires the commitment of launch capacity for that purpose.

Interplanetary and deep space missions face similar limitations inherent to dependence on chemical propellants. Although gravitational assist has been a regular tool used in both navigation and imparting changes in specific orbital energy; obtainable velocities, launch windows, and other flight parameters remain severely limited by dependence upon the same Newtonian Propulsion methods used by the ancient Chinese to power their rudimentary rockets. Even Ion Propulsion, which uses electro-magnetic acceleration of the ion fuel to achieve impulse, is still a type of Newtonian Propulsion where the total energy imparted is limited by exhaust velocity and total available fuel mass; as defined by Tsiolkovsky's rocket equation. Newtonian Propulsion may have gotten us to earth orbit and beyond; but it will be Electro-magnetic propulsion that will carry us to the stars. In the mean time, its development will allow us to achieve flight parameters unimaginable when considering only chemical propellants.

The Ampere Defined As Magnetic Force:

Prior to 1948 the ampere was defined, based on Faraday’s Law Of Electrolysis, as the amount of unvarying current, that when passing through a solution of silver nitrate, deposits silver at a rate of .00111800 grams per second.

The ampere was redefined in 1948 as the amount of unvarying current, that when being carried by two infinitely long conductors separated by one meter, would generate a magnetic force between the conductors of 2 X 10-7 Newton per meter of length. This is the Standard International definition of an Ampere.

Electro-magnetic Field Reaction Propulsion and Electro-dynamic Induction Braking when combined with the now and near term future technologies related to super conductivity and other related technologies will introduce a new paradigm in space propulsion.

The Fundamentals Described As A Space Based Experiment:

A simple space based experiment to demonstrate the basic principles of electro-magnetic propulsion is easily imagined. In this experiment a simple coil, a number of accelerometers, a polarity reversing switch, power source, and radio telemetry is used to determine the earth’s electro-magnetic field strength at the range of the experimental package. It would be most advantageous if the coil length is as great as possible. The coil is circuited in series with the polarity reversing switch and the power source. The accelerometers serve to activate the polarity reversing switch. The experiment is then suitably packaged and conventionally launched to a low inclination orbit defined by the optimum induction flux angle. The experimental package is then positioned so that the field coil of the package is aligned so the coil will be at maximum repulsion with earth’s electro-magnetic field when the coil circuit is initially energized.

So positioned, when the switch is initially closed and power is applied to the coil there will be two vector forces acting on the coil.

Since the coil is aligned in repulsion with earth field, one force will be acting along a line that is perpendicular to the earth’s North/South polarity (approximating the line of orbital radius) and will translate to an acceleration vectored along the orbital radius converting circuit energy to increased gravitational potential.

The other force acting on the field coil will translate to torque causing the field coil to begin to rotate about the central axis of the coil length as it begins to align towards the magnetic equilibrium position relative to earth field; that being one of maximum attraction and 180 degrees relative to the maximum repulsive position. In doing so, some of the electrical energy supplied to the field coil will be converted to kinetic rotational energy of the package. As the field coil rotates towards the equilibrium position, the accelerometer reading acceleration along the line of the orbital radius will sense zero acceleration as the angular relationship between the field coil and the earth’s North/South polarity reaches 90 degrees relative to the maximum repulsion or attraction position. The coil polarity control circuit is designed to reverse the polarity of the field coil at this position, thus maintaining a repulsive relationship as the rotational inertia carries the coil package through the 90 degree position.

The timing of the polarity reversing switch is critical for maintaining repulsion; avoid dampening the oscillation, or allowing the package to continue increasing its spin velocity.

As power is applied to the circuit, energy begins to be converted thru linear and rotational acceleration to the gravitational and rotational energy of the package. Without empirical proof, I suggest that the applied coil circuit energy will be the sum of the energy translated to gravitational potential and rotational kinetic energy. That the linear force acting along the line of orbital radius will vary as the cosine of the relative field angle while the force translated to torque about the center axis of the coil will vary as a sine function of the relative field angle. The linear force will approximate the force at 0 degrees (maximum repulsion) times the cosine of the relative field angle. The force imparting torque about the center axis of the field coil will approximate the force imparting torque about the center axis of the field coil at 90 degrees (maximum torque) times the sine of the relative field angle.

Where the moment of inertia of the experimental package is known, Earth’s Electro-Magnetic Field Strength can be derived from acceleration and circuit power.

Attitude Determination and Control Applications On Board Earth Based Satellites:

Using the Earth’s magnetic field as a reaction field in attitude determination and control of earth orbiting satellites was first proposed early on in space science applications history. Current applications include the sensing of relative field angle to determine satellite attitude and the use of electro-magnets to maintain and change satellite attitude. The author believes that widespread application may be limited by the orbital perturbation that would result from earth field/satellite field interaction. Electro-magnetic attitude control, without an Electro-magnetic orbital maintenance regime, would require expenditure of thruster fuel to maintain orbital station. To make electro-magnetic attitude determination and control a viable application, a means of offsetting the orbital perturbation using electro-magnetic propulsive technology rather than chemical thrusters must be developed. Also, the mass and volume fractions of electro-magnetic attitude determination and control technologies must be brought to values where the advantages of the technology offset the mass and volume fractions required. A primary advantage of Electro-magnetic propulsive methods for this application is that it can be accomplished without the complex mechanical components as required in momentum and reaction wheel technology or the fuel and valving required for thrusters. This resulting increase in reliability will serve as further incentive to apply electro-magnetic technology to attitude control.

Increasing Hyperbolic Excess Speed in departure from Earth’s sphere of gravitational influence:

By definition, for an Earth orbital escape mission, the Hyperbolic Excess Speed is the residual speed that remains as the space craft climbs out of the Earth’s gravity well. Simply stated, it approximates the rocket burn out velocity minus the escape velocity at the range of burnout.

It may be possible to increase the Hyperbolic Excess Speed by using magnetic repulsive force generated by propulsion coils aboard the spacecraft acting against Earth’s electromagnetic field. The repulsive force would offset the deceleration of gravity as the space craft moves out of the Earth’s gravity well. This offsetting force would leave more residual or “Hyperbolic Excess Speed” as the space craft leaves the gravitational sphere of influence. If the magnetic repulsive force exceeds the gravitational force, then this force would continue to accelerate the space craft. The additional energy imparted would approximate the applied circuit energy calculated as applied power times time.

By thoughtful design, repulsion can be maintained without using an oscillating polarity strategy (as described in the Space Based Experiment), thus maintaining constant space craft attitude.

Increasing Hyperbolic Excess Speed in Gravity Assist Maneuvers:

A number of deep space missions have used Gravity Assist to either increase or decrease the mechanical energy of the space craft. Although such maneuvers use the gravitational acceleration of the assisting planet to increase or decrease the heliocentric relative velocity of the space craft, the Hyperbolic Excess Speed of the space craft relative to the assisting planet remains unchanged. The reason for this is the relative velocity between the space craft and the assisting planet gained by the acceleration of gravity on the approach trajectory is lost to that same gravitational force on the departure trajectory.

By using Electro-magnetic Field Reaction Propulsion, both additional hyperbolic excess speed relative to the assisting planet and heliocentric relative velocity can be imparted when the assisting planet has a significant magnetic field. In this application the propulsion coil(s) are used in attraction polarity on the approach to the assisting planet. This increases the acceleration above that imparted by gravity alone.

As the space craft begins its departure trajectory from the assisting planet, the relative polarity is reversed and maintained in repulsion. This offsets the deceleration imparted by gravity, and increases both the Hyperbolic Excess Speed of the spacecraft relative to the assisting planet and the Heliocentric Velocity; by adding the energy imparted by the electro-magnetic system to the specific mechanical energy of the space craft.

If desired, the inverse process could be used to decrease spacecraft energy.

Orbital Station Maintenance and Altering Eccentricity:

By using properly timed Electro-magnetic Impulse, in repulsion and in attraction, possibly combined with Electro-dynamic braking; total orbital energy and eccentricity of orbit may be altered. Conceptualization of this regime involves both magnetic impulse and dynamic-braking at specific points in the orbit and could include using the induced dynamic-braking energy to produce vectored magnetic impulse.

Orbital Energy, often described as “The Specific Mechanical Energy”, has two components. These are the kinetic energy per unit mass and the gravitational potential per unit mass. The sum of these two variables equals the specific mechanical energy. In a mass constant orbiting object, when not acted on by any other force than the gravity of the prime focus object; this Specific Mechanical Energy remains constant. In elliptical orbits this energy translates between kinetic energy and gravitational potential energy.

Introductory texts on Astro-dynamics teach that in most cases, a change in the Specific Mechanical Energy of a satellite is accomplished by imparting impulse along the velocity vector. This change in velocity translates to a change in the semi-major axis of orbit. By imparting impulse along the velocity vector the Specific Mechanical Energy can be either increased or decreased with the timing of the impulse relative to periapsis or apoapsis determining orbital eccentricity. Changes in apoapsis are made by imparting impulse at periapsis while impulse to change periapsis is imparted at apoapsis.

In both cases, the impulse either increases or decreases the total orbital energy by imparting a change in orbital velocity. This change in velocity is then translated to a change in gravitational potential by altering the semi-major axis.

It is proposed that changes in the orbital energy of the space craft can be made using Electro-magnetic technology; increasing the orbital energy by increasing the semi-major axis directly through repulsive interaction with earth field or decreasing orbital energy by electro-dynamic braking.

In a properly inclined orbit, generating a magnetic field in repulsion with earth field will begin to impart impulse along the orbital radius, increasing the semi-major axis, thus directly increasing the gravitational potential component of the Specific Mechanical Energy. By imparting magnetic impulse during the entire orbital period, or applying bit impulse relative to apoapsis and periapsis, the orbit can be stepped up and eccentricity controlled. If using conventional chemical propellants, stepping up the orbit is accomplished by increasing the velocity component, translating to gravitational potential, with the impulses timed relative to apoapasis and periapsis to control eccentricity. Experimentation with generating magnetic field in attraction to earth field may yield some surprising results. How will the circuit energy be conserved?

Electro-magnetic Induction Braking (Electro-dynamic Braking) of the space craft will impart a braking force along the vector of orbital velocity, decreasing the orbital energy, and translated to a reduction in gravitational potential. By timing the Electro-dynamic braking inputs relative to periapsis and apoapsis the orbit can be stepped down and eccentricity controlled. Using chemical propellants stepping down the orbit is accomplished by impulse opposite the velocity vector, slowing the spacecraft. The timing of braking impulse relative to periapsis and apoapsis will allow control orbital eccentricity.

Electro-dynamic Induction Braking:

All electro-magnetic induction processes are composed of three primary components; the excitation field, the inductor, and rate of change. The rate of change can be supplied by velocity of the inductor relative to the excitation field, the oscillation of the excitation field in the presence of the inductor, or combination of the two.

For those of you who may have had the opportunity to empirically experience the fundamental physics of induction through experimentation with a simple hand crank generator, that lesson showed the relationship of circuit load to cranking force, and can be extrapolated to the inductive braking of a satellite or asteroid. In Electro-dynamic Induction braking applications the solar or planet field will provide the excitation field while coils aboard the spacecraft, or the spacecraft/asteroid body itself, serves as the inductor. The spacecraft/asteroid velocity cutting the flux lines of the Solar or Planet field will supply the rate of change component. This induction process will generate a braking force as is inherent in any electro-magnetic induction process. The induced energy will then be dissipated through circuits designed to generate heat for radiative dissipation, conversion to vectored propulsive impulse, or stored for peak power/subsystem applications. Applications of Electro-dynamic braking will include adjustments in semi-major axis and eccentricity; as well as braking to orbit in planetary missions.

Because the orbital velocity of a satellite or asteroid is so high, significant voltage can be developed even though the excitation field may be very weak. The “tether” experiments flown on the space shuttle clearly indicate the validity and potential application of this technology.

Imparting Orbital Escape Energy:

Escape speed, as given in reference material, gives the escape speed at the surface of the body referenced. This escape speed decreases as the radius of orbit increases. If an orbiting spacecraft is given continual magnetic impulse to step up the orbital radius, at some point, the orbital velocity of the spacecraft will approach and then exceed the escape speed at range, thus allowing the spacecraft to “escape” the gravitational sphere of influence of the prime focus body (planet or Sun). Using such a method, a satellite may be given Excess Hyperbolic Speed, not by imparting additional velocity, but by imparting additional gravitational potential until the energy of the spacecraft exceeds that needed to escape the gravitational sphere of influence of the prime focus body.

By initiating high power Electromagnetic impulse in low earth orbit and maintaining this impulse during the outbound trajectory, very high Excess Hyperbolic Speeds might be achieved.

Braking to Orbit:

A space craft approaching Jupiter, or other target body, may have too much energy to establish orbit. By using Electromagnetic Propulsive methods it may be possible to alter both the magnitude and vector of the approach velocity; thus giving an alternative to using chemical propellants or atmospheric braking as the sole methods of reducing the energy of the spacecraft so that it can be captured by the intended prime focus body. Deep Space Propulsion and Navigation:

Force vectoring will be obtained by very precise control of field strength, field angle, and action time relative to the reaction fields of planets having significant field, the Sun, and once beyond the heliopause; the galactic field. Vector control, when within the magnetic sphere of influence of multiple field sources; will utilize the relationship of reaction field range, reaction field angle, and time span of power input to sum the force vectors from two or more reaction fields to obtain the desired net force vector. An example would be to act in repulsion of earth field for a fixed time at a fixed power and then act in attraction to Sun field for a fixed time at a fixed power. The net vector force would be the vector sum of the two forces. Because of the cosine relationship of repulsion/attraction force to the relative angle between the propulsion coil(s) and fields of the Sun, Earth, Jupiter, or other reaction fields, and if those fields are offset at a substantial angle relative to each other; effective impulse vectoring can be accomplished.

In Closing:

The Delta V imparted by a chemical rocket is limited by the attainable exhaust velocity of the rocket and total fuel mass available. In an Electro-magnetic Field Reaction Propulsion System capable of generating extreme field strength, the Delta V imparted will be limited only by the amount of available applied electrical power and the time span that power is made available. In all cases, the minute field strengths of the reaction fields at range become usable when the propulsion system is capable of generating extremely strong fields or, in the case of dynamic braking, the induction circuit is capable of maintaining extremely high acceptance when dissipating high power. The use of Electro-magnetic Propulsion may negate the requirement of waiting for opportune alignment of Jupiter and Saturn for use in Gravity assist maneuvers. The launch windows now continuously open by the ability to use Solar Field in repulsion to give the space craft the kick up that would otherwise require a gravity assist trajectory or maneuver.

A most important ramification of Electro-magnetic Field Reaction Propulsion and Electro-dynamic Braking in Space Applications may be the fundamental change in the logistics of asteroid deflection. This technology will negate the need to carry chemical fuel mass to the asteroid for the purpose of supplying impulse. It will allow mankind to use the orbital energy of the asteroid itself as the prime source of energy for deflection through an integration of Electro-dynamic braking, vectored electro-magnetic impulse, and for powering Newtonian Propulsion Systems that use scavenged mass from the asteroid and accelerate it using propulsion coils. Perhaps, it will cause a re-evaluation of the decision to use nuclear explosive deflection and fractionation as the preferred approach to this impending challenge.

--Mark J. Carter 23:42, 23 September 2007 (UTC)


 * Has this been published? Someguy1221 02:28, 24 September 2007 (UTC)


 * See Electrodynamic tether. Theoretical work was done in the 1980s, with testing in subsequent years.--SpaceSailor (talk) 23:10, 20 January 2014 (UTC)

No short notice defense?
The possibility of altering the course of an asteriod if it´s found months or years in advance is obvious. Blast a few thermonuclear explosion near it, equip it with a sail, the like. But the article carefully circumvents showing the options if the thing is only detected a day before impact, which is highly likely for a thing of 250m or so in diameter. There seems to be the credo "we mustn´t break it", but i ask myself why?

Asteriods are most likely very loose objects, so if we can disperse the thing, a lot of small pieces < 1m will just burn up in the atmosphere, and the bigger pieces will hit over a large area, but each will be much less dangerous. The gravity on such an asteroid is very small, so it shouldn´t have time to reassemble, and if one thermonuclear explosion isn´t enough, the USAF Global Strike Command and their fellow bastards in Russia, China and France will finally have found a constructive use for their arsenal of ICBMs.

I´d rather have a few hundred or thousand craters less than 50m in diameter across half the planet, than a single hit, causing global nuclear winter, and probably wiping out a third of China in a big fire, or half of North America and Europe under a giant tsunami.

I see that it´s quite ugly, but we´ve blow up hundreds of nuclear bombs in our atmosphere, so the added radioactivity, very finely dispersed, will not be a problem. There will probably be thousands of people being hit by meteorites. Sucks for them, but half of them would probably have died anyway, along with billions of others in the famine during global winter.

So what´s the problem? Why is this not adressed, neither here nor elsewhere? Simply because it´s the obvious last-minute-resort, and there´s no chance to ever try it out? --129.13.72.198 (talk) 00:13, 6 September 2013 (UTC)


 * Yes I think you hit the proverbial nail on the head, it is the last "minute"/week resort. Problem is, there are presently no large ICBM's that can really launch their nuclear warheads out of earth orbit. The heaviest lift (AKA) highest throw weight ICBM is the R-36/Dnepr-1 and even that struggles to lift 3 metric tons into geo-stationary orbit. Humanity once had a vehicle that could launch enough payload/ a large enough fraction of the Earth's nuclear weapon arsenal, in the form of the Saturn V, but in humanity's infinite wisdom (that's sarcasm),we presently have no Super Heavy Lift Vehicle, and our closest Heavy lift launch vehicles don't come anywhere near to the Saturn V's lift capabilities.


 * So it's the only possible last minute resort, but because of the rubbish launch vehicles in service now, it wouldn't be very effective at all, you would have your described shotgun like buckshot spread effect of asteroid rock raining down upon the planet as opposed to the majority of the chunks missing earth if hit with a Saturn V carrying a nice complement of mulit-megaton warheads. And to add insult to injury, large thermonuclear warheads are increasingly being dismantled in favor for smaller lower yield weapons, like the B61, so if an asteroid was detected in 1969-1972, humanity would have been able to send hundred's of 25 megaton B41s and 9 megaton B53s on Saturn V's, R-36s and Titan IIs respectively, but now, all we could muster in a short space of time of about a week would be a handful of 1 megaton B83s and 0.3 megaton B61s launched by R-36s and the like.
 * Makes you shake your head in disbelief, doesn't it?
 * About the only thing that could make up for this is if B61 equipped RNEPsRobust Nuclear Earth Penetrators were launched at the incoming threat, as their penetration capabilities would more than make up for the B61's reduced yield. Of course humanity has very few of those in stock though as the RNEP got a lot of resistance from the anti-nuclear media a few years ago and was never effectively developed, but who knows...maybe it was? Let's hope it was. Merry Christmas/Nollaig sona duit
 * 86.40.91.237 (talk) 17:00, 22 December 2013 (UTC)
 * Saturn V never had a 1-week launch capability--not even close, only missiles with warheads had/have short launch capabilities.SpaceSailor (talk) 22:01, 13 January 2014 (UTC)


 * The Saturn V did have a 1 week launch capability, it could sit in the Vehicle Assembly Building unfueled and then be rolled out for launch in under a day. Please cite a reference that suggests otherwise, as I'm highly skeptical of your statement.
 * As for the RNEP, I think the conventional Massive Ordnance Penetrator probably could be retro-fitted/ or already is designed to contain the B61 and since it reportedly can achieve 50-60 meters of 5000 psi reinforced concrete penetration, it probably fulfils the RNEP design specifications. I'm both glad and disturbed by this.
 * 86.44.238.236 (talk) 04:43, 17 January 2014 (UTC)
 * No Saturn V ever sat around in the VAB awaiting some random mission to show up. Each was committed to a specific launch before being assembled.  Taking one from VAB to pad required an entire working day--that just got it to the pad, not launch ready--that may be the 'one day' you had heard of.  One of my associates walked out every one of the Saturn Vs, and I am familiar with what had to happen.  They typically sat on the pad for weeks before being launch ready.  But since they no longer exist, they are not even available for this application.--SpaceSailor (talk) 21:30, 19 January 2014 (UTC)
 * Take a look at the Space Launch System page for NASA's heavy lift proposal--bear in mind NASA is better at proposing projects than implementing them. According to NASA SP-4204, a Saturn V could sit on the pad for about 2 months before being ready for launch.--SpaceSailor (talk) 02:20, 20 January 2014 (UTC)


 * Yes I've helped edit the SLS page, pretty much all the pictures were added by me, as was the booster competition section and upper stage section, fingers crossed NASA will keep getting funding and the project doesn't get cut - which is the reason why they are often regarded as better at "proposing projects than implementing them" - politics not engineering. As for the Saturn V, I notice you say "could", yes it could take that long, it could take even longer with a storm hitting Florida, but it could be done in a much shorter time span.
 * http://apollomissionphotos.com/index_org_sky1.html - The Skylab 1 Saturn V had a VAB rollout on 16 April 1973 and was launched on May 14th. - Less than a month and that was a first of it's kind payload. If I'm not mistaken, most of the checks necessary on the launch pad were for the payload (which was often carrying humans) and not on the engines and tanking time, engines which already had gone through hundreds of hours of ground testing. Since one of your associates allegedly worked on the vehicle, you could ask him what took up the majority of the time to get to launch ready status? Regardless of our difference of opinion in the exact amount of time it could be done in, the essence of the point I was trying to make above was exactly what you just said -"since [flying Saturn V's] no longer exist, they are not even available for this application."
 * 86.44.238.236 (talk) 03:58, 21 January 2014 (UTC)

In the News
BBC News April 22, 2014: Asteroid impact risks 'underappreciated'. --BatteryIncluded (talk) 01:12, 23 April 2014 (UTC)
 * This is all based on (Brown & al. Nature 503 [14/11/2013] 238-241). They did not include infrasound data for 2014 AA. -- Kheider (talk) 02:26, 23 April 2014 (UTC)

Not that anyone will care, but
I came up with the solar sail proposal in 2004, and sent it to NASA. I never received a reply email, but I've seen this scenario posted at a couple of different discussion groups. I'm not sure if I should be pleased, or pissed that I was never credited with the original idea. I guess my small claim to fame, if it helps everyone, should be just that. A small claim. I just hope it works if they go to use it. -Tercero


 * solar sail was invented in 1924. Somehow I don't think the idea of using them to deflect asteroïds waited 2004 and you.--Musaran (talk) 19:54, 3 October 2009 (UTC)


 * : Not to mention that the Solar Sail idea was proposed at the beginning of the 1998 movie Armageddon, where it was quickly rejected given the timeline of (iirc) 18 days. Zeldafreakx86 (talk) 21:29, 25 July 2014 (UTC)

graphic of deflection methods compared
http://www.neoshield.net/en/mitigation-measures/overview.htm In their 2010 report Defending Planet Earth: Near-Earth Object Surveys and Hazard Mitigation Strategies, the US National Research Council (NRC) identified four broad mitigation options and classified them by NEO impactor diameter and the warning time available before impact.

Original source Image by Tim Warchocki, Copyright © National Academy of Sciences from NRC report available at http://www.nap.edu/catalog/12842.htm

Could someone good with that computer ink graphics maker copy the general message of the image and put it in this article? 178.167.196.163 (talk) 13:20, 4 September 2014 (UTC)

ref name="defending Earth"
Hello, I am the IP editor that edited the above article a few days ago, I appreciate your attempt but your edit has now introduced a serious reference error.

Notable the referenced page(77) that you put in support of the following section of the article is incorrect, that page discusses how nuclear deflection works, it does not discuss politics. Could you please correct this?


 * " This bill "to provide for a Near-Earth Object Survey program to detect, track, catalogue, and characterize certain near-Earth asteroids and comets" was introduced in March 2005 by Rep. Dana Rohrabacher (R-CA)."

92.251.211.17 (talk) 03:36, 6 September 2014 (UTC)
 * Hello. The reference was not introduced by me. What I noticed was that the exact same reference was introduced 3 times in the article so I only changed the format used for multiple citations of the same reference. I admit I did not read the reference nor check that it was used in the correct context. Please feel free to fix the errors you detect and make a note in the edit summary just before you save the page. Thank you, BatteryIncluded (talk) 01:23, 7 September 2014 (UTC)

Sufficient "megatonnage" to deflect asteroid exists?
According to a book in 1964. My understanding is that about that time nuclear warhead design yields became smaller so that they could fly on precision-guided ICBMs, rather than being dropped imprecisely from strategic bombers. Also a number of arms control pacts have been signed since. The statement is ambiguous and source is out of date. Whether an off-the-shelf warhead could do the trick is (and was) dubious. Geogene (talk) 18:31, 21 May 2015 (UTC)
 * It really does depend on how it's employed. A small-yield nuke used as a shaped charge might readily divert an asteroid from its course. (Something the writers of "ST:TNG", & you, have evidently not considered...)  TREKphiler   any time you're ready, Uhura  22:52, 21 May 2015 (UTC)
 * I am sure that if such situation develops, neither the Russians or Americans would complain or hesitate to use a nuke to save the planet,as it would not be a military mission but one of survival of the Homo species. BatteryIncluded (talk) 23:05, 21 May 2015 (UTC)
 * My concern was not political refusal to fly a nuclear mission, but the availability of megaton-range warheads and their mass. But I see that according to this (Figure 4) an Icarus-sized asteroid could be deflected by a nondescript nuclear warhead if done >15 years before impact. Removing tag. Geogene (talk) 00:29, 22 May 2015 (UTC)

Charon disambig?
Could someone more familiar with this subject matter take a look at this sentence?

"For comets in the range of the then estimated 100 km diameter, Charon served as the potential example."

Can we confirm that this should be pointing to Charon (moon), or to something else?

Thanks KConWiki (talk) 14:10, 21 February 2015 (UTC)


 * Perhaps they were referring to comet/centaur 2060 Chiron? Charon is 1200 km and bound to Pluto. -- Kheider (talk) 15:13, 21 February 2015 (UTC)


 * I take it none of you actually went to the bother of just reading the reference that is attached? https://e-reports-ext.llnl.gov/pdf/232015.pdf Planetary defense workshop LLNL 1995. Pg 258 and indeed pages before and after it clearly state it as ChAron. All this speculation that they were talking about ChIron is post-hoc without any contextual understanding of what was known about ChAron at the time of publication, moreover it is completely devoid of all adherence to the rules on WP:OR for you editors to have inserted ChIron on the grounds of your own personal speculation.


 * I have since reverted your post-hoc reasoning. Desist in adding speculation without first corroborating it with references.


 * Perhaps you could research and then write up the evolution of understanding about the nature and size of ChAron, specifically focusing on measurements prior to the year 1995, as a form of redemption, and report your findings in its article page.
 * 178.167.254.173 (talk) 03:53, 12 April 2015 (UTC)


 * There has never been a 'Charon type comet' as mentioned in the referenced article; there are Chiron type comets. The article has a typo. Here is a 1989 reference mentioning Pluto's moon Charon: https://books.google.com/books?id=DN-v0fQSfPkC&pg=PA869&dq=charon+class+comet&hl=en&sa=X&ei=_8gqVdPLLceXNrqegbgM&ved=0CKYEEOgBMFo
 * Chiron type comets: https://en.wikipedia.org/wiki/2060_Chiron#Cometary_behavior
 * Bkobres (talk) 20:15, 12 April 2015 (UTC)


 * The moon Charon was/is considered a KBO/comet. --> http://csep10.phys.utk.edu/OJTA2dev/ojta/course1/comets/overview/oort_tl.html Secondly, you still haven't posted about what the best estimates on the diameter of Charon were in 1995. Were they greater than 100 km in diameter? Or pretty much 100?
 * The Planetary defense workshop article does not appear to have a typo, as Charon with an A is what is discussed, and this spelling is used multiple times across a large number of disparate pages, yet Chiron with an I is never mentioned at all in the entirety of the document!.


 * Therefore the only way you could convince me that the article does have some kind of endemic "typo" as you suggest, is, if you track down the best estimates for the diameter of Charon, in or around the year 1993-5, and those estimates are not anywhere close 100 km. Is this not a reasonable level of evidence for you?
 * 31.200.157.49 (talk) 02:44, 28 May 2015 (UTC)

Teller workshop
The Tsar bomb stuff is WP:SYN and I couldn't find the stuff about "instantly vaporizing" asteroids with 1 GT warheads in the LLNL workshop proceedings. That paragraph is getting silly, needs better sources. Geogene (talk) 03:48, 28 May 2015 (UTC)


 * The "instantly vaporizing" of a 1 km wide body by a 1 gigaton NED(nuclear explosive device) is indeed in the LLNL document. Read it.
 * 178.167.152.146 (talk) 17:11, 17 June 2015 (UTC)


 * Optimal scenario, a water comet pre-heated to the vaporization temperature: 1 km sphere of ice = 5.2*10^11 L =~ 5.2*10^11 Kg of ice, requiring 2.2*10^6 J/Kg specific heat of vaporization, or 1.1*10^18 J. The energy equivalent of 1 gigaton of TNT is only 4.2*10^18 J. In other words, once you have somehow preheated the comet nucleus to the vaporization point, you still have to transfer the heat from the warhead into the nucleus at at least 25% efficiency, which is not possible. Vaporizing a stoney body with no iron is risible. More importantly, it isn't in the source. And there are other problems as well, including WP:PRIMARY. Geogene (talk) 00:10, 18 June 2015 (UTC)

Failed Verification: Neutron heating
I need a source to verify the following sentence: These effectiveness figures are considered to be "conservative" by its authors as only the thermal X-ray output of the B83 devices was considered, while neutron heating was neglected for ease of calculation purposes. This source does not support it, it says that the figure is "conservative" because the bomb is good for 1.2 MT, not the 1.0 MT in their analysis (see page 15). There's nothing about it in this source:, which only says that they ignored everything but thermal x-rays. They ignored everything else according to Source 1 because the compositions of asteroids is not well known and because the radiative output of the bomb is classified, and they were limited to unclassified material. Read the sources before edit warring over them, and try to use them accurately. Geogene (talk) 21:37, 21 August 2015 (UTC)

Geogene (talk) 21:47, 21 August 2015 (UTC)


 * Are you joking? even the 1 page reference I added to stop your tendentious tagging, displays the fact that the 2007 NASA study, that you acknowledge "says that they ignored everything but thermal x-rays". Also has, right next to this very sentence that you acknowledge is in there, a graph plainly showing that this NASA study that remember ignored neutron heating, has drastically underestimated nuclear effectiveness when it is shown next to all the other peer-reviewed studies that DO include neutron heating, such as "Dearborn"'s.
 * So really, there's not much point going much further until you acknowledge this.
 * Boundarylayer (talk) 22:04, 21 August 2015 (UTC)
 * While I'm also frustrated with your editing style, you still don't seem to comprehend the issue. Part of the problem is that you're interpreting primary sources, which you ought not be doing. Obviously this will require some form of dispute resolution. Geogene (talk) 22:10, 21 August 2015 (UTC)
 * Let me post this again: the sentence that needs to be supported is: These effectiveness figures are considered to be "conservative" by its authors as only the thermal X-ray output of the B83 devices was considered, while neutron heating was neglected for ease of calculation purposes. Please continue re-reading until you see the problem. Geogene (talk) 22:12, 21 August 2015 (UTC)


 * By all means, request for a comment if you wish, however I may be seeing a glimmer of hope in you. Are you saying that now you see the graph? Great! Secondly, there is no "primary source problem" as these papers are all peer-reviewed. Thirdly, I supplied the report that has the authors stating this fact*, then when you tagged it, I supplied the 1 page ref to only re-enforce the fact that, indeed the authors are conservative in their performance estimates as unlike many others before them, they did neglect neutron heating.
 * See page 15 here, The analysis depends on only X-ray interaction with the asteroid. Neutron interaction is neglected as it is more difficult to predict spectrum and interaction with the asteroid, and that neutron interaction will occur after X-ray interaction
 * It's all right there in plain english.
 * Boundarylayer (talk) 23:51, 21 August 2015 (UTC)
 * I've raised the question at the No Original Research Noticeboard . Geogene (talk) 01:04, 22 August 2015 (UTC)

The repeated use of the word "could" is FUD
Recently, I have had to repeatedly change the wording of the nuclear deflection strategem section to reflect what the sources themselves contain. As other editors, (who I now see here on this talk page, also have a history of personal antipathy towards this section of the article) continually editorialize the section with "coulds" and "maybes".

Furthermore, in their reversions of my edits, back to the original tone of "would" and "according to simulations" etc. They contend that the sources actually say "could" and that "we don't know".

Yet the very sources they're referring to include:How it Would Work: Destroying an Incoming Killer Asteroid With a Nuclear Blast

Which doesn't leave any room for doubt how it 'would work. Not "might" or "could" as they like to prefer, but would work, according to the supercomputer simulations.

It's therefore plain as day that their preferred "could" is editorializing FUD. Boundarylayer (talk) 03:34, 20 August 2015 (UTC)


 * You're reading certainty into the source that just isn't there, that's editorializing. Why did you restore the link to Operation Fishbowl, which has nothing to do with this article? Geogene (talk) 03:52, 20 August 2015 (UTC)


 * Here we go. From the Popsci article:
 * "All this depends obviously on exactly where the intercept is done, how far away from the Earth it is, how much time we have left--and all of these are unknowns until we discover a threatening asteroid," Weaver says. "All of these assumptions are assumptions. What I think I'm bringing to the table for the first time are truly validated simulations of these non-uniform, non-circular compositions that will hopefully give policy makers a better understanding of what their options are."


 * No need to trust his numbers more than he does. Geogene (talk) 03:58, 20 August 2015 (UTC)
 * Pinging Continuing to take the source out of context, particularly since that only applies to asteroids of a certain size class. Geogene (talk) 04:13, 20 August 2015 (UTC)


 * (1) Operation Fishbowl has a great-deal of connection with this topic, as its objectives were to detonate nuclear explosive devices in space, and it achieved that. So it serves as somewhat of a precedent, and therefore meets the re-quirements for inclusion within the see also section.


 * (2) With respect to Popsci & the Cielo computer simulations. I have included numerous times the sentiment that -this would, according to simulations do...xyz. I have done this expressly so as to remove the need for inserting the misleading and weasel-esque "could" & maybe" sentiments, that others have taken it upon themselves to inject into the section, and done so without authoritative sources to back-up this editorializing/altering of the sentiment.


 * Now if you found reputable sources questioning Weaver's assumptions, only then would I agree to inserting shaky "could" sentiments about what he has found, until then however, it is needlessly misleading. Especially when I don't see the problem with saying this would, according to simulations do...xyz
 * Boundarylayer (talk) 04:31, 20 August 2015 (UTC)


 * (1) You haven't addressed that the Cielo simulations represent asteroids of a paticular size range, which you have represented simply as "asteroids".


 * (2) That Fishbowl detonations were done in "space" and any asteroid mission would be in "space" also is an extremely superficial similarity. This article is about asteroid deflection, nuclear weapons are only of passing interest here.


 * (3) After I quoted the Popsci reference here, looks like you pulled it and substituted a more primary source instead . (Nevermind, I see it became a new paragraph--placing more weight on the popsci source, but without addressing the points I made above. What are your plans for the article? Geogene (talk) 17:23, 20 August 2015 (UTC) Geogene (talk) 17:32, 20 August 2015 (UTC)

(1)I don't need to address that, as Weaver doesn't either, precisely because what works on the medium scale with say explosive device of medium size, will work on the large scale with a similarly upscaled/tailored explosive being delivered.

(2)While the article is about asteroid avoidance this sub-section is about putting nuclear explosive devices in space, therefore as I've already explained to you. It meets the requirments to be within a see also list.

(3)I'm glad you've ceased making false claims about that source and injecting the "could"s everywhere. Boundarylayer (talk) 05:32, 21 August 2015 (UTC)


 * The available physics packages will only deliver a yield up to a particular size. Basically what's happening here is that if "asteroid" can cover objects from a few meters up to 20 km in size, then there must exist some category of asteroids sufficiently small that they can be destroyed by a nuclear weapon. Suggesting that we could just design a bigger warhead is not realistic when Weaver and Wie are both focusing on short-notice events. Your effort to extrapolate their work to cover all possible asteroids is misleading, especially when your source for Weaver has Weaver suggesting nukes are a last option. All of this means that "could" is a better term (and your accusations of FUD, which I understand is considered a type of propaganda) are not only absurd, but probably a violation of behavioral guidelines. So if you can't help but put nonsense in the article, please at least refrain from being obnoxious in the process. Geogene (talk) 18:16, 21 August 2015 (UTC)


 * Now, some salient quotes from Wie's NIAC Phase II study to illustrate my argument above:
 * Thus, for the most probable mission scenarios, in which the warning time is shorter than 5 years, the use of high-energy nuclear explosives in space will become inevitable. A scenario in which a small (e.g., 50 to 150 m) Earth-impacting NEO is discovered with short warning time is considered the most probable scenario because smaller NEOs greatly outnumber larger NEOs, and smaller NEOs are more difficult to detect. (page 15)


 * When the warning time is very short, disruption is likely to become the only feasible strategy, especially if all other de­flection approaches were to fail, as was concluded in the 2010 NRC report [10]. However, it is again emphasized that non-nuclear techniques should be preferred for non-destructive deflection of hazardous NEOs whenever we have sufficient mission lead times (>10 years).  (page 16)


 * For larger targets: From Fig. 1.8, we notice that a 1-Mt nuclear disruption mission for a 1-km NEO requires an intercept-to-impact time of 200 days if we want to reduce the impact mass to that of the Tunguska event. A 270-m NEO requires an intercept-to-impact time of 20 days for its 300-kt nuclear disruption mission to reduce the impact mass to that of the Tunguska 11 event.  Therefore, it can be concluded that under certain conditions, disruption (with large orbital dispersion) is the only feasible strategy providing considerable impact threat mitigation for some representative, worst-case scenarios. [that'll be pretty hard to fly with less than a 5 year warning, won't it?] source:  Geogene (talk) 19:13, 21 August 2015 (UTC)


 * And for Weaver: The simulations suggest that a 1-megaton nuclear blast could deter a killer asteroid the size of Apophis or somewhat larger. (pdf page 2)


 * Weaver will next turn to simulating larger and larger rocks of varying compositions up to the size of a “dinosaur killer” (about 6.2 miles across). (pdf page 4) [Anybody seen those calculations?]


 * “From my perspective,” he says, “the nuclear option is for the surprise asteroid or comet that we haven’t seen before, one that basically comes out of nowhere and gives us just a few months to respond,” says Weaver.


 * So a nuke "could" disperse a small enough asteroid. Not "would", and the article exaggerates the likelihood of success, the knowledge of asteroid composition, and the enthusiasm scientists have for this option [as a desperate last choice] Geogene (talk) 19:29, 21 August 2015 (UTC)

Geogene (talk) 19:36, 21 August 2015 (UTC)


 * Your suppositions are incorrect. The most glaring of them is your repeated attempts to draw in the fact that nuclear-use would be the emergency option with the entirely unrelated issue of what the Cielo computer results of Weaver state. When to the un-biased eye, it really doesn't matter what humans decide to do, that still doesn't change the fact that the simulations say what WOULD happen in the event of a nuclear interception that is energetically tailored to the size of the asteroid.


 * Secondly, you're contradicting yourself, on the one hand you've thankfully acknowledged "Weaver will next turn to simulating larger and larger rocks of varying compositions up to the size of a “dinosaur killer”", yet on the other hand you have the unrelated, contentious and un-supported argument that "The available physics packages will only deliver a yield up to a particular size". That's just another red herring. Furthermore, US warheads, like the 9 Mt B53 in storage, has a yield almost an order of magnitude greater than the 1.2 megaton device frequently modeled against the ~300 m Apophis, and it is "available", now that's just in the US. The Russians have a 20 megaton device in storage that was previously on top of their R-36 (missile) from 1976 and 1984. Moreover, much larger yield devices are easy to quickly make. Just ask the Soviet Union in 1961. - Tsar Bomba.


 * All the sources indicate that nukes are being proposed as an emergency option for short notice issues, if the article fails to get that across, it violates the Neutrality policy. And that's not a contradiction: Weaver and Wie still have to work with what's available off the shelf, and only in papers and simulations are they permitted to choose their asteroid. The potential yield of any specific bomb design is limited by the laws of physics. I'm not interested in what the Russians may or may not have laying around in storage, because the sources don't seem to care, they all use B63s. "Easy to quickly make" is unrealistic and OR, please stop making the article imply that that's the case. Sources are talking about a warning of five years or less, potentially down to a few months, combined with a necessary intercept time of at least 200 days before impact for a 1 km target. You're making the article say: "No problem!". I object to that, because none of the sources even remotely agree with it. Geogene (talk) 22:51, 21 August 2015 (UTC)

Again, I fail to understand your argument, how does the results of a computer simulation on nuclear detonation intercepts, need to be tempered with "could"s? Simply because, to you, what "would" happen solely depends on how humans decide to act?

Moreover your above diatribe is grossly misleading. The detection of any >40 m sized incoming asteroid would always be an emergency, unless we had decades, then it'd be just a smaller emergency depending on its exact size. Furthermore, all the sources indicate that NEDs(nuclear explosive devices) are proposed for dealing with both long-distance large threats AND short notice small threats. The article does get this across, I hope? Secondly. "nukes"/nuclear technology is proposed in every major and therefore credible option. From getting kinetic impactors up to speed, to powering tugboats/gravity tractors for decades on end, so the "only in an emergency" thing is just plain wrong, as even when a tugboat would work, a large chunk of "nukes/nuclear material" would still be used. Chemical and solar power are just not up to muster for all but the smallest of threats. If you've read anything more than a little on these non-detonating approaches you'd know they are also generally "nuke" powered at heart.

In that vein, even if we have decades to deal with a moderate sized asteroid and humanity decides to go with the tug boat/gravity tractor mission option, that would conceivably prevent an earth impact, but only by a close shave, we'd still have an asteroid with an orbit dangerously close to earth, circling round us like a shark. What do you propose to do with that? Sure, if it is useful we could mine it etc, but if it's not, we'd have no other choice but to keep up these gravity tractor missions for even more decades until we're satisfied it is far enough away with little to no chance of ever coming back. That doesn't strike me, nor anyone who has thought about it as a great solution. As the alternative argument that will no doubt be issued is: We could do that, or we could go with the cheaper-faster-better route of giving it a good NED push to begin with. A solution that isn't open to clandestinely moving NEOs/asteroids back onto collision courses with Earth - a real possibilty that is open to all the other options, as they can steer asteroids around.

On Weaver and Wie. They don't "all use" the 1.2 Mt B83, some that I've seen use the 9 Mt B53. Secondly they have to work with what's on their shelf for a number of reasons. While no US report that I know of, examines in-depth the possibilty of using Russian NEDs, with the explanation for that probably foremost being that they have detailed information about the performance of US NEDs, and so naturally producing reports on what US NEDs can do, specifically those intended for the Robust Nuclear Earth Penetrator role is technically and politically their best option. While another factor may be that they probably get a "kick-back" from the gov/military for not saying-->"and we'd rely on the russians if the shit hit the fan!", which would be politically unwise to report. Although in this document, by none other than Weaver himself, on the last or 2nd to last page, Weaver actually does hint at asking the Russians/the international community for making the right choice on which specific NED to use, in an actual real-world asteroid-incoming scenario. HERE

With respect to "No problem!"? Where did I write that? While I am accurately summarizing the various reports, it may appear that I am saying "no problem" as nuclear explosive devices(NEDs) are the most versatile of all the avoidance solutions (which the NASA quote in the article even supports). I actually think it would be a major problem to get the NEDs to the asteroid. As greatest impediment to every option, not least the nuclear deflection option is the lack of sufficiently large rocket vehicles. NASA are slowly getting back to building an outer-space vehicle with the SLS(the block II variant) but really we could do with the Saturn V being brought back into service, even as a museum piece, standing ready for launch in a few weeks.

Although I think the article should indeed include that, but I've yet to come across a good source that really explains this obvious problem, that every deflection technology intrinsically faces.

Lastly, nuclear explosive devices are easy to make. Andrei Sakharov produced a conservative design for the 50-100 Mt tsar bomba and it was made in a couple of months(well before we had legacy codes and supercomputers). You can read his memoirs if you like, it's in that. So it's neither "unrealistic" nor "OR". Boundarylayer (talk) 01:46, 22 August 2015 (UTC)


 * Here's a calculation of the physical effects from 50m asteroid impact, as viewed from 10 miles away . It's a 7 MT explosion. Not impressive, you simply evacuate the local population 50 miles or so, this is a lot easier than space travel, especially on short notice. The only problem is if some moron tries to nuke it, and alters the landing site just before impact, as happened in a war game that took place at the recent, much-discussed planetary defense conference. Source: . Geogene (talk) 02:39, 22 August 2015 (UTC)
 * This makes that glib assertion in the article that everyone will be fine, legally, with using a nuke against any old asteroid that might be a threat very questionable. Nuking a big asteroid will look like saving the world, nuking a small one will look like target practice. This article continually fails to make the distinction between little asteroids and threatening ones. Geogene (talk) 02:45, 22 August 2015 (UTC)


 * Firstly, Those effects of nuclear weapons based calculations-fudged-into-service-for-determining-impact events are not accurate, decent for an approximation, but by no means accurate. Check the Brown quote I added on the Chelyabinsk meteor article, and Tunguska page and how those calculations ignore "momentum" etc.


 * Secondly, it would be criminally negligent to let an impactor hit earth with the destruction of property, as emergency evacuation/crisis relocation plan of an area and then the destruction of that area is all when and good on paper...as long as it's not going to be your house or country/world, am I right? No one would fault a country attempting to prevent an impending natural disaster, as long as they do the job right and don't put others in danger by doing so.


 * Thirdly, the "war game" as you call it, relayed within the economist article,(cutting through their own editorializing nonsense on the broken window fallacy they like pushing), actually seems to be making the point that; if humanity is going to conduct a deflection mission, we better make it an international affair and with that, do it right the first time round. That is, not hold back/"be a moron" with puny kinetic impactors that may not work against a target made out of rubble(which transpires in their hypothetical scenario). Instead, have, if not as the initial attempt, but at the very least have as an immediate back-up, the ability to hit the threatening object with a series of stand-off nuclear detonations until sufficient deflection is achieved. That's the take home message I read in that article. Lastly, how exactly would it be seen as not saving someones world, but "target practice" if a small asteroid was deflected? I really don't follow you there.


 * Whatever successful method that will be used(eventually) will be described as "saving the world/livelihoods" of thousands/millions if the asteroid happened to be heading near your or "their" homes.


 * Boundarylayer (talk) 23:47, 30 August 2015 (UTC)


 * Melosh is probably the world's foremost expert in modeling the effects of impact events. If you've got a problem with those numbers, then Wikipedia isn't the place to fix it. Likewise for the rest of the above. Geogene (talk) 17:14, 31 August 2015 (UTC) Added later: Now I see the problem, you've confused Melosh with the models they use for small airbursts. It's apples and oranges; and a good cautionary tale about interpreting primary sources. Geogene (talk) 18:06, 31 August 2015 (UTC)


 * Coming in a bit late, but it seems to me "could" is apt, here, since a live trial has never been done, so what would happen is, still, unknown. To use a somewhat faulty analogy, it's the difference between wind tunnel results & the actual aircraft...  TREKphiler   any time you're ready, Uhura  18:45, 31 August 2015 (UTC)


 * User:Trekphiler I thought we had this edit dispute sorted out ages ago by simply saying "this would, according to computer models and experimental results, do xyz"? So there is no need to couch the whole thing with "coulds" everywhere, as if no one has done detailed supercomputer analyses and experimental tests on meteorites or anything. When they actually have. Are you still not satisfied with this?


 * Geogene, Why did you assume I was arguing about the exact size of craters? Seen as you used the explosive unit of "7 MT"/ megatons, I thought it was obvious we were discussing that figure & the resultant area of death & destruction it would cause. Melosh's quick-n-dirty impact effects software here - is even acknowledged by the team in their attached pdf, to be based on the effects of nuclear weapons 3rd edition. In 2007 supercomputer analysis by Boslough proved that this is a crude approximation. Here Sandia 2007  I recommend you get yourself up-to-speed on these modern publications before declaring your belief that his above site is super-accurate again. Really, it strikes me as odd that you're not aware of this as you actively edit both the Tunguska & Chelyabinsk meteor article, were I stationed this, & other references years ago.
 * Boundarylayer (talk) 22:47, 31 August 2015 (UTC)


 * I think that trying to explain this to you further will only generate diminishing returns. Geogene (talk) 23:13, 31 August 2015 (UTC)
 * With that sentiment, I do agree. There appears to be unresolvable disagreement on what "could" & "would" mean in this context.  TREKphiler   any time you're ready, Uhura  02:08, 2 September 2015 (UTC)

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Separate out detection efforts
Most of the Deflection efforts seems to be about Detection efforts. Propose we separate out threat detection and impact prediction from deflection efforts (to avoid duplication with other articles). - Rod57 (talk) 14:43, 21 January 2017 (UTC)

Timeline
One of the bullet points in the Planetary Defense Timeline section claims that (as of 2007) ALL objects of concern (> 140 m) will be identified and monitored (whatever that means) by 2020 C.E. This claim is blatant nonsense; we can not identify "all" of them because the number of them is constantly increasing ( or 'constantly changing' if you remove objects which are no longer part of that category). I see this article has "benefited" from a flame war, so I'll leave my other comments aside - other than to remark that a lot of it is quite opinionated and appears to rely not only on the editors' opinions, but puts forward statements in editorial and opinion and advocacy writings as if they are established fact. We have a better method of determining what is fact and what is opinion (and what is false): its' called peer review.67.140.179.46 (talk) 16:03, 26 June 2017 (UTC)

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Could mention HAMMER
, kinetic and nuclear options. - Rod57 (talk) 01:13, 11 March 2018 (UTC)