Nuke Bad Comets


Abstract: Appropriate use of technology is paramount, as civilization tremble, and the Earth turns into a gas chamber. The way drones have been used to kill extra-judicially in violation of the Fourth Geneva Convention, is deeply inappropriate. Yet, drones can be used very appropriately on a battlefield. But to use them to bomb millennia of Western morality, is definitively inappropriate. Our technology is turning us into gods, but we better be smarter than the Greek ones of lore. Remember what happened to the Greeks.

The way nuclear energy has been used has often been inappropriate. Yet, nuclear energy shortened up World War Two by several million deaths. Nukes could also save billions, should a bad comet suddenly appear.

Comet Pan-STARRS Visible This Weekend

Comet Pan-STARRS Visible This Weekend

The comet pictured above was detected by the Pan-STARRS telescope in Hawai’i. It’s a “sun-grazer” comet with an elliptic orbit of 106,000 years (so it’s predictable). Perihelion: .302 AU, March 10 (today!). So it is getting as close to the sun as Mercury gets periodically.

Guess what? By a troubling coincidence one such bad comet has precisely just surprised us. OK, it’s not coming for us, but how many of those are there out there? Obviously more than we thought.

Space faring nations with the appropriate technology, nuclear, military, electronic and ballistic, such as France and the USA, should make well financed contingency plans to prepare to engage such a giant object with a nuclear bomb upon very short notice. This is not trivial, because of the unusual speeds and energies involved. The technology would also allow to intercept “city killer” asteroid, even with only a few hours’ warning (after dialing down the megatonnage of the bomb).

Only nuclear energy would work to deal with large impactors, forget big tales for small children, about painting them blue or something. One does not deflect comets with brooms, or firecrackers, but with an explosive energy a million times greater than what Genghis Khan used. That we fortunately have mastered. If we are masters of our souls, we can be masters of fusion.



Cosmic warnings are piling up. On January 3, 2013, a comet was discovered. It’s called C/2013 A1. It is on a hyperbolic trajectory, and moves in a retrograde orbit. That means it may be extra solar, and should be leaving the solar system. Maybe it is coming from outside the solar system.

Comet C/2013 A1 is on a collision course with Mars.

October 2014?

October 2014?

Even The Economist, the rogue free market magazine I subscribe to, in “Hits Keep Coming”, thinks that the big governments’ program promoted by the present essay is a good idea, and would give something meaningful for NASA to do

A crucial articulation of the present Greater Depression is that people in Western countries are running out of meaningful things to do, as the plutocracy has deliberately robbed them of employment and power, thus meaning. This essay speaks of struggling against comets, but that will not happen, before a bit of class struggle.

C/2013 A1 is a completely different style of comet from Pan-STARRS. C/2013 A1 is hyperbolic, not elliptic. It means that the comet has so much kinetic energy that, should it not collide this something first, it will escape the Solar System.

C/2013 A1 will come so close to Mars that it may well hit it (comets, because they emit jets of steam, behave a bit like rockets: they can go sideways). Should C/2013 A1 collide with Mars, the event should be most remarkable.

The current estimate of the absolute magnitude of the nucleus M2 = 10.3 indicates a diameter from 10 to 50 km. Worse: the energy imparted is proportional to the square of the velocity, and that velocity is very high, much more than what is needed to escape the sun. C/2013 A1’s speed would be approximately 56 km/s by the time it approaches Mars. By comparison the Solar System’s escape velocity in the vicinity of Mars is 34km/s! The comet has more than twice the energy needed to go visit other stars.  

The energy of impact on Mars, should it happen, might reach the equivalent of staggering 20 billion megatons of TNT!



We are lucky that C/2013 A1 is heading towards Mars and not Earth! One has to understand that big planets are for comets like honey strips for flies. They attract them.

That effect protects us. Jupiter is our existing Spaceguard system: it sucks in comets. Jupiter has 318 times the mass of the Earth, making it literally 318 times more attractive for comets (from the gravitation law that Isaac Newton reminded us a scientifically minded French priest had found earlier; often misattributed to Newton nowadays, in a spirit of manifest Anglo-Saxon, hence Wall Street-City of London supremacy).

Two large comets collided with Jupiter in the last two decades. That changed the mood among professionals.

Pre-Socratic philosophers would have been fascinated by all the understanding we have gathered on all these celestial bodies. They were already fascinated, as all this astronomy shook their metaphysics to the core. Before Socrates, it was thought that thinking had to do with learning about what was out there. (After Socrates-Plato-Pluto, it was thought the universe was all about what was in one’s heads. And, sure enough, within a century, plutocracy, Macedonian backed plutocracy, had won all over… Except the Roman republic. Who said metaphysics had no impact?)

In 466 BCE, Halley’s comet passed by for the longest time, 75 days. Simultaneously, an enormous meteor (perhaps associated to the comet) crashed into Northern Greece. A piece, as large as a wagon, landed on the ground and stayed a tourist attraction for more than 5 centuries. That shattered the ancient theories of the Greeks about the heavens. Anaxagoras’ science came to the fore.

The Greeks would  have been fascinated by Comet Shoemaker–Levy 9. Irresistibly attracted by the giant planet, that 15 kilometers diameter comet came too close to Jupiter. Shoemaker-Levy, quartered by Jupiter mighty gravitation, broke in 70 pieces or so, and went back to space. Still irresistibly attracted, the comet, now a train of comets of all sizes, hit the gas giant on its next pass. The pieces entered the Jovian atmosphere, making giant black impacts in it.

Each of the largest 7 fragments’ explosion was bigger than Earth herself. One explosion made a giant dark spot over 12,000 km across, and released an energy equivalent to 6 million megatons of TNT. That unreal succession of impacts into Jupiter in July 1994 blasted smugness about the stability of heavens to smithereens. Astronomer David Levy stated: “The giggle factor disappeared after Shoemaker-Levy 9”.

As the comet would pack 20 billion tons of TNT, something packing a few million tons of TNT may help Earth to negotiate with it. I want pacifists munching grass placidly in those vast, awesome Elysian fields in their heads, to meditate upon that.



Nuclear energy, because of the basic reason that, by a factor of a million, nuclear energy is the greatest energy source we have. This is why the main problem of our civilization has become the problem of nuclear energy. How to use it appropriately, and not freak out.

If the comet were heading towards Earth we would be scrambling to put together a giant thermonuclear weapon. It could be done. The French republic, by itself, could do it, using in-house equipment. The chance of success, though would approach 100% if, and only if, one were to prepare well, in an international program.

Lots of Uranium 235, and Lithium 7, for a bigger bang, in the monster fission-fusion-fission thermonuclear device we would be hastening to prepare. One of several (because we would need back-ups). If we were really pressed for time, we could rigged together several conventional nuclear warheads, packed together to explode simultaneously. 

As NASA puts it in 2012: For non-technical reasons, this would likely be a last resort, but IT IS ALSO THE MOST POWERFUL TECHNIQUE and could take several different forms, as discussed in the report. The nuclear option would be usable for objects up to a few kilometers in diameter.

The efficiency of a thermonuclear explosion is augmented by an order of magnitude if it happens three meters below the surface rather than on contact, one centimeter above the surface. So NASA (2012) has proposed to extend the Nuclear Explosive Device with a frontal penetrator which would create a three meter crater. Easy computations show that, had the hyperbolic comet headed towards Earth, the interception speed would have been at least 80km/s, meaning that the thermonuclear fusion sequence would have to be started just before first contact.

Fast Electronics Required @ 80km/s

Fast Electronics Required @ 80km/s

Of the shelf H bombs could take care of comets a few kilometers across.

The power of nuclear devices is hard to fathom. The Castle Bravo device made a crater in the atoll reef. Although it was exploded 7 feet above the reef, the crater  had a diameter of 2 kilometers (6510 ft), with a depth of 80 meters (250 ft). It would have been much worse if it had been buried by 3 meters (five kilometers across, 160 meters deep).

For larger comets, a true bomb from hell would have to be devised: a fission-fusion-fission with a powerful third stage. A third stage is simply a Uranium envelope around the thermonuclear bomb. When it gets hit by “fast neutron” from the H bomb, it fissions in turn. The largest bomb ever tested, Tsar Bomba, over the arctic island of Novaya Zemlya, was 58 megatons TNT. It was deliberately made with NO third stage. (And the second stage may have contained some lead, instead of uranium.)

It’s not that a third stage is hard to make; it’s just uranium metal. But Soviet physicists computed that, with a third stage, Tsar Bomba would have been too powerful. The plane dropping the bomb and its parachute would have been destroyed, to start with. As it was windows were broken more than 1,000 kilometers away, in Finland and Norway. Because so little uranium was used, relative to the Lithium Deuteride fusion fuel, the mightiest bomb ever was also the cleanest, ever, at 97% pure fusion. (Fusion is cleaner because it fuses light elements to create slightly heavier, but still light, elements, and light elements tend not to be fission, or then not for long.)

By enriching the third stage tamper with U235, one could probably go beyond 200 Megatons (and such a tamper could be rigged around conventional warheads, too!).

Thus, contrarily to urban legend from luddites in denial, the largest thermonuclear bombs could take care of the largest comets.

Man-Made Fireball 8 Kilometers Across.

Man-Made Fireball 8 Kilometers Across.

The largest comets are 60% larger than the entire picture, if one uses the fireball as a measuring unit.

Even the largest comet would fragment and the pieces would rocket away. If done a few weeks before Earth impact, clearly all the pieces would miss (another rocket or two would be in back up, just in case).



So let’s suppose again that C would be headed towards Earth instead of mars.

The next Ariane V would have to be modified hastily. Why Ariane V? First, that flight is already being assembled. It is Flight VA213, signifying the 213th launch of an Ariane from French Guiana since the family’s maiden liftoff in 1979. Its Automatic Transfer Vehicle, named Albert Einstein, would have to be modified with a booster, interception electronic package and basically a boom system in the front to detonate fast enough the nuke in the back, at the staggering speeds involved, so that the bomb can explode at 3 meter depth in the comet… 200 megatons against 20 billion megatons. Fun. Unreal reality.

In general, Ariane is the most dependable, most frequently launched rocket in the West’s arsenal. So it should be part of the quick reaction force to be assembled, as one would need to fling a hefty load.



When “experts” come, and talk about the frequency of impacts, the truth is that we do not have any idea what it is, up to a factor of ten, or more. It is certainly higher than what experts used to believe. three cometary impacts, or near impacts of comets on planets close to us in 20 years is a bad omen.

I was listening to National Public Radio where some scientist from John Hopkins pontificated that the asteroid strike in Siberia (which, a few tens of seconds off could well have annihilated a  major city) happened only every century. In truth, on land three impacts about ten times bigger are known in the last century. Scaling with the ocean, one gets nearly ten of these ten times bigger impacts. Not to say that this is the long term average: it could be a fluke. The same stupid guy was saying that, if we had only 6 months warning, we could not do anything.

And he works on preventing impacts! NPR said.

But what he forgot to say is that his program strictly uses the explosive technology Genghis Khan already had at his disposal. (And what happened? After a costly victory in Hungary, the Tumens had to turn back, them and their fancy black powder rockets.)

(Scientists should stop pontificating, or talk as if they knew, when they don’t, reserve that to the Pope.)

There may have been other impacts in historical times. Unrecorded.

Strange events happening in the Sixth Century, recorded by Chinese and Romans (the only civilizations recording anything reliably at the time) could be explained by impact(s) at sea. (Or then a large volcanic eruption, unidentified so far.) Those events, whatever they were, altered the climate.

Some will smirk, and ask to see the craters. Celestial bodies colliding with the Earth are not on any kind of trajectories. They are ruled by the sun, that is they tend to have trajectories similar to the Earth, but at an angle. So a typical impact will involve a low angle atmospheric entry, spreading death, fires, shock waves and devastation for thousands of kilometers. A crater will not necessary form (elongated craters have been found in Argentina). And remember, 2/3 of Earth is water.

Speaking of which, a proposed impact, the Mahuika impact, 1443 CE, off the south coast of New Zealand, would have been gigantic, typical of a mini comet 500 meters across. There is some evidence for such a cometary impact, from the existence of a crater, from Maori evacuation of the area, to suspected tektites, to suspicious ice cores in Antarctica, to megatsunamis, up to 220 meters high in the region (and 143 meters high in Australia).

So much for these things being rare.



In recapitulation: learn to do what you can do about what matters.

Lord Martin Rees, Astronomer Royal, Nobel Laureate, etc. in Science Mag. editorial “Denial of Catastrophic Risks”, March 8, 2013: “In a media landscape saturated with sensational Science stories and “End of the World” Hollywood productions, it may be hard to persuade the wide public that real catastrophes could arise as unexpectedly as the 2008 financial crisis, and have a far greater impact. Society could be dealt shattering blows by the misapplication of technologies that exist already … we should be more concerned about events that have not yet happened but which, if they occurred even once, could cause worldwide devastation.”

What Rees is saying is that we should change MOODS. We should change our system of mood. Preparing for a comet impact, and how to defeat it would help to change the mood we have about moods.

We need to learn to deny our Denial of Catastrophic Risks.

And we learn to do something about catastrophic risks we have identified (I call this new way of thinking catastrophic calculus). Having an active Spaceguard program against asteroids and comets of all sizes and origins, hyperbolic or not, would be a good symbol of the new attitude we need to adopt. Besides, it would reduce unemployment, and push technology forward.  That’s appropriate.


Patrice Ayme

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10 Responses to “Nuke Bad Comets”

  1. de Foucaud Says:

    Nous adorons nous faire peur avec des prédictions de fin du monde de plus en plus fréquentes et qui font un flop! Elle arrivera dans notre système solaire dans un certain nombre de milliards d’années inévitablement. Nous avons trop tendance à raisonner dans notre échelle de temps de vie sur cette magnifique planète au demeurant. L’arrivée de l’homo sapiens sur terre est très récente et surtout très courte en regard de l’échelle de temps cosmique ; une étincelle en quelque sorte. La conscience et la maîtrise exponentielle des des technologies nous offre la perspective d’être immortels, soit, mais la superpopultion de note planète ne nous détruira t’elle pas avant un impact de météorite, ceci ramené à l’échelle de temps cosmique ?

    PS : les anglophiles traduiront.


    Envoyé de mon iPhone


    • Patrice Ayme Says:

      Salut Paul! Comme j’essaye de l’expliquer, ce n’est pas une question d’avoir peur, mais une question de trouver une signification suffisante pour pouvoir etre employe’ intelligemment. Carl Sagan had advocated to do nothing, lest the technology of deviating asteroid would be detoured (as the sci-fi writers Niven and Pournelle had also considered) for military purposes.
      But I am not advocating deflection technology, which is extremely unlikely to be used, anyway, as I already explained (as slowly converging asteroids had plenty of time to already slowly converge… hahaha).

      My point, made at the end of essay, was precisely that fighting comets is good, FIRST OF ALL, by CHANGING THE MOOD. Martin rees was talking about the sort of issues you are talking about. BTW, it’s not a billion Africans who are ruining the biosphere, they are ruining Africa.


  2. Dominique Deux Says:

    Unless we bomb an incoming with its exact replica in antimatter, the impact and explosion, however satisfying by Hollywood standards, will only replace the incoming spheroid by an incoming, expanding debris cloud whose barycentre will follow the same velocity and trajectory.

    This might in fact increase the risk of major impacts in the case of a comet with a grazing orbit; at any rate it would be a choice of massive grapeshot vs massive cannonball, not an inspiring one.

    Trajectory diversion is needed and could only be achieved by a crew (human or robotic) landing on the enemy combatant body and fitting it with large nuclear-powered rockets, so as to steer it out of the way.

    A much more interesting project, IMHO, than the neanderthal approach of hurling missiles at bad bad thing in the sky, like the jawbones protohumanoids launched at the Slab in Space Odyssey.


    • Patrice Ayme Says:

      Dominique: Hmmm… Wow. Dominique: Courageous you are to boldly step in the maw of the Tyranosopher. I guess I should add a P/S…

      1) Any nuclear bomb creates a fireball. The temperature of the fireball is initially 100 million degrees Celsius (about 180 million F). That’s ten times more than in the center of the sun. Then the fireball expands. In the case of Tsar Bomba, a nearly pure fusion device, the temperature was that of the surface of the sun, eight kilometers across.

      2) The same would occur with a large part of even a giant comet. Many cubic kilometers of the comet would be brought to temperatures well in excess of that of the hottest rocket engine, and actually hotter than any material can stand. The resulting plasma would become part of the fireball, and act as a giant rocket engine. This effect is very well known, and can be observed even in tiny chemically driven explosions with low temperature. It’s basically the principle of a steam engine, and, not uncoincidentally, comets are mostly made of water. So a large thermonuclear nuke would turn even a giant comet into several rocket propelled fragments, expanding radially from the explosive center. In a day the expanding debris cloud would be more than 100,000 kilometers across (the distance at which the hyperbolic comet is suppose to pass by Mars).

      If the explosion is to the side, as it should be, the fragments will go the side. (Newton’s Third law.)

      3) There is no more need of humans as there is in Israel’s “Iron Dome” anti-missile system.There are now many anti-missile systems. Rockets in such systems can endure gigantic accelerations, definitely unhealthy for even insects. The Franco-European Aster anti ballistic missile missile is capable of more than 60 gs sideways, to the point thrust is applied from wingtips at center of mass (otherwise missile would break).

      4) Soft impactors do not go through the atmospheric wall. A large H bomb shockwave would shatter any space body into lose material.

      Anyway, NASA said it, it works. What I added is that, for a 50 kms comet, one would have to rig a three stage nuke, and it would be better to be ready to with a provision of Li7 and U235, for a much bigger bang.


      • Dominique Deux Says:

        Sorry to harp on. Errare humanum, perseverare diabolicum, and the Devil is often right.

        “a large thermonuclear nuke would turn even a giant comet into several rocket propelled fragments”

        That is precisely the rub. Because I cannot agree with your assumption that a side hit would steer the whole debris cloud to the opposite side – that would be true if the hit was from a body roughly the same mass as the oncoming. But an explosion is multidirectional and a nuke has a negligible mass and therefore inertia.

        The one configuration where an explosion would achieve the right “steering off” would be a heads-in hit with a shaped charge (think bazooka or Panzerfaust). Then the shockwave would indeed act as a sharp stake and drive the comet’s contents from its central axis and therefore its trajectory. But such a hit would be very difficult to achieve with the needed accuracy – landing and positioning the charge would be actually easier (no humans needed as I already wrote).

        And this still assumes no large fragments will truck on at the rear. Nuclear bombs are very hot indeed but not all-destructive – see underground tests in the Pacific, with dire predictions of doom never fulfilled (bar the Godzilla movie). Assuming that only small debris will remain, to enliven our sky as harmless falling stars, sounds very optimistic.

        Whether aiming at an axial explosion or at fitting the comet with directional “rockets” without fragmenting it, mastering an AI-driven sequence of distant landing and complex earthworks would be a necessity. Such a technology would be extremely useful in other situations – think asteroid mining (and Earth oil exploration, alas). And it is not that undoable – we’re very close to it in fact.

        So I stick with my guns – don’t blast the thing and cross your fingers; steer it out of the way and at the same time acquire a very marketable set of skills.


        • Patrice Ayme Says:

          dear Dominique: I am afraid you did not read my two essays on the subject very carefully. It also baffles me a bit that you think people with doctorates in physics don’t get it, for something that elementary. NASA (2012): EXPLODING A NUCLEAR DEVICE IS ALSO THE MOST POWERFUL TECHNIQUE and could take several different forms, as discussed in the report. The nuclear option would be usable for objects up to a few kilometers in diameter.

          You seem to believe that a thermonuclear fireball cannot deliver momentum. That’s completely mistaken. Project “Orion” showed it was feasible to make a pulse thermonuclear engine lifting a 10,000 tons rocket. The idea was to explode a succession of H bombs below a special plate protected by special liquids. To Saturn in a few weeks.

          First light has momentum. Tremendous light has tremendous momentum. Momentum, not “inertia” is the relevant concept.
          Second… OK, maybe I scramble an essay on (some of) the physics of nuclear bombs…

          Anyway, I thought I had been explicit enough to the point of being boring… Guess not…


  3. pshakkottai Says:

    The massive grapeshot would be preferable because many small pieces will be vaporized by the atmosphere and some will miss the earth entirely. If the asteroid is too close we are out of luck. Considering that our missiles are really slow compared to the incoming asteroid we should launch the missiles days ahead probably.


  4. victor Says:

    When you say”Jupiter has 318 times the mass of the Earth, making it literally 318 times more attractive for comets (from the gravitation law that Isaac Newton reminded us a scientifically minded French priest had found earlier; often misattributed to Newton nowadays, in a spirit of manifest Anglo-Saxon, hence Wall Street-City of London supremacy).” Which french priest are you talking about? I was not able to find his name on the net. Thank you in advance for your answer


    • Patrice Ayme Says:

      Hi Victor, and welcome to the comments! I think the history of science is crucial, not because of celebrity contests, but to show exactly how ideas progress, and what backs them up. (For example how in hell could Newton contrive to believe that NEWTON’s own rings proved light was made of particles? Just because he wanted desperately to contradict Huyghens?)

      Bulliadus, in analogy with light, PUBLISHED IN 1645, when Newton was three years old, that Kepler was wrong about the attraction law. And what the correct law was:

      As for the power by which the Sun seizes or holds the planets, and which, being corporeal, functions in the manner of hands, it is emitted in straight lines throughout the whole extent of the world, and like the species of the Sun, it turns with the body of the Sun; now, seeing that it is corporeal, it becomes weaker and attenuated at a greater distance or interval, and the ratio of its decrease in strength is the same as in the case of light, namely, the duplicate proportion, but inversely, of the distances that is, 1/d².

      As Bulliadus was a priest, he edged himself as Buridan had done, three centuries before, when the latter exposed the mathematics of why the geocentric solar system was false.

      Newton himself proclaimed the precedence of Bulliadus, who was one of the earliest members of the Royal Society (that was more elegant, to put it midly, than Einstein with Poincare’!)


  5. Patrice Ayme Says:

    To Dominique and other skeptics of non conventional wisdom: Steering NEOs presents ethical, diplomatic and military problems. Following Carl Sagan, I do not advise to develop the technique.

    If one has 6 months, and a fortiori 6 hours to act, steering is no option. As I explained in the essays, steerable NEOs are no danger anyway.


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