Asteroids are Stronger, Harder to Destroy

Computer modeling at Johns Hopkins finds that asteroids are stronger than we used to think and require more energy to be completely shattered.

In the early 2000s, a different research team created a computer model into which they input various factors such as mass, temperature, and material brittleness, and simulated an asteroid about a kilometer in diameter striking head-on into a 25-kilometer diameter target asteroid at an impact velocity of five kilometers per second. Their results suggested that the target asteroid would be completely destroyed by the impact.

The new model accounts for the more detailed, smaller-scale processes that occur during an asteroid collision. Previous models did not properly account for the limited speed of cracks in the asteroids.

The impacted asteroid retained significant strength because it had not cracked completely, indicating that more energy would be needed to destroy asteroids.

Icarus – A new hybrid framework for simulating hypervelocity asteroid impacts and gravitational reaccumulation.


• This paper presents a new computational approach to investigating the consequences of major impacts into asteroids.

• The approach uses a recent model for materials under impact conditions, integrated with a long-timescale gravitational computation.

• The work provides new insights into the potential disruption of asteroids through collisions.


We present a hybrid approach for simulating hypervelocity impacts onto asteroids. The overall system response is separated into two stages based on their different characteristic timescales. First, the short-timescale fragmentation phase is simulated using a modified version of the Tonge–Ramesh material model implemented in a Material Point Method framework. Then, a consistent hand-off to an N-body gravity code is formulated to execute the long-timescale gravitational reaccumulation calculation. We demonstrate this hybrid approach by considering the 5 km/s head-on impact of a 1.21 km diameter basalt impactor on a 25 km diameter target asteroid. The impact event resulted in the fragmentation, but not complete disruption, of the entire target. A granular core is observed at the end of the fragmentation simulations, which acts as a gravity well over which reaccumulation occurs in the N-body simulations. Our results suggest that disruption thresholds for rocky asteroids are higher when energy-dissipating mechanisms such as granular flow and pore collapse are included.

SOURCES- John Hopkins

Written by Brian Wang

58 thoughts on “Asteroids are Stronger, Harder to Destroy”

  1. Sorry if I came ac cross snarky. I got a bit repetitive, I was sorta drunk when I wrote the comments. Though they are accurate. In my area of expertise, the process is the most important thing. That is what you try to identity first and find an analogous one that serves as a sort of baseline.

  2. Sigh… As Dr. Pat noted, your reply is a result of not reading my comment in the context of the other comments I penned here on the same subject from differing angles.  

    To whit: we (you, I, Dr. Pat, many others) all agree that the real goal is to NUDGE the discovered-to-be-a-killer impactor away from its Earth-damaging orbital path to a degree where at worst it is merely a “near miss”, but a miss nonetheless.  This is what my other comments are about.  

    The point of my calculating the impact-yield (which your comment critiques as inappropriate tho it really is, FOR AN IMACT) was to point out that the impact yield wouldn’t be a “multi-gigaton boom” as you said, but rather thousands-to-millions of gigatons.  

    While we could mice words regarding what “multi-” means, “millions” doesn’t seem to fit in common parlance. 

    Anyway, again… we agree: nudging a big object is better. 
    And there are multiple ways proposed to do so. 

    Peace, brother.

    PS: Dr. Strangelove is my favorite movie of all time. Good handle.

  3. Ah, actually, I think it is concomitant on you to do the calculation, you know?  

    Just saying,

  4. No: I wasn’t trying to be a smart-ass, friend. I like the word and its connotations. And I read ALL your comments, with appreciation. Sorry if my tone came across otherwise.

  5. Nobody is talking about bringing the asteroid to a stop.

    You’re getting confused by the calculation of how much damage the asteroid could cause on impact.

    It’s the same calculation, but that doesn’t mean that an actual deliberate stop is being discussed.

    I’ll admit that you have to read all of Goat’s comments for this to be clear, but I thought my comment was self contained.

  6. The energy required to bring asteroid to a stop is utter nonsense even to think, let alone compute and use as an argument for or against anything. Even if it were possible, it would still be nonsense. Prevention of impact can be achieved by deflection, which still takes astronomical energy, but most importantly time – has to be done years in advance, which is implied to be not the case when such an asteroid suddenly becomes a threat. That makes deflection unrealistic in the strictest sense. What realistically can be done has to be possible on short notice – months, perhaps even weeks. That implies that all assets exist in sufficient quantity, pre-positioned in space and ready for use. It will still take weeks or months to reach the target at safe distance, but application of energy at gigaton scale (multiple 100Mt devices) at a singe point on target of any relevant composition will result in fragmentation, deflection of larger fragments, and elimination of smaller ones, due to physical conditions of high-yield bursts in space – primarily X-rays, which heat material in volume. Surface layer of target material will blow up and generate massive thrust impulse, also create destructive internal forces in entire volume due to center of mass change. That applies to large fragments too.

  7. I think you’ve misunderstood Goat’s comment completely.

    He IS calculating the energy yield of an impact. He IS calculating the energy of bringing the mass to a stop. Because he is calculating the energy that the rock would release if it hits the Earth.

    I agree that this doesn’t exactly address your point, but that’s what he addresses in the other comments that he references.

    And what’s a synfrome?

  8. Yes. That is what I calculated. The kinetic energy of the asteroid that was used to hit the other asteroid in the original model that this article is about.

    The result was much larger than any nuke we have lying around, but it still wasn’t enough (according to the modelling) to destroy the bigger asteroid.

  9. Your numbers show kinetic energy of asteroid, not the energy to physically destroy it. Now you know, I guess.

  10. Let’s not devolve to “syndrome” tagging with me.
    Everything you wrote in the comment above is wrong, and I will explain.

    1. You computed the equivalent yield of an impact, which is irrelevant to the problem. The entire idea can be reduced to preventing impact, making yield non-realised, and — in simplest terms — making all that kinetic energy go elsewhere. What you computed is something like the energy to bring that mass to a stop, which is nonsense.
    2. Instead of me reading your other comments, I suggest you read a book on nuclear weapons (“nuclear weapons effects”, google). Specifically, look at computation of crater size for high-yield weapons. Or just use a web simulator (“NUKEMAP”, google) set to 100Mt and surface burst. I have just done it: the crater radius is 900 meters, depth 430 meters. That is about the maximum practical yield for fusion device, and the conditions of detonation at asteroid. It follows that several sequential detonations at one location would deepen the crater to the point where most of the energy is absorbed by asteroid material. Taking into account the generated thrust, and its own rotation, asteroid would likely fly apart in large chunks due to change in its center of mass, even if it is solid iron. If it is rock, it would definitely fly apart as rock does not endure large straining forces that would be generated inside by energy deposition.
    3. The size is wrong. Most likely target is sub-kilometer, worst case is several kilometer wide – destructible.
  11. If broken up could pulverize to dust by sending several, several kilometer long spinning cables in the direction of the asteroid debris. Entangle, smash and redirecting the smaller pieces. If such an asteroid can be broken.

  12. Use the old Orion design of nuclear charges designed to focus a plasma blast in one direction. It was especially designed precisely to impart thrust to huge slabs of iron.
    In which case the OP result, that the asteroid will hold together and not shatter, actually helps.

  13. “Glucose is 100% problem free”. Not exactly:
    Glucosepane is the worst crosslink. No way for the body to get rid of that one…and so far no known supplement/drug either. As we age, it greatly outnumbers the other crosslinks. That is part of why I am an AGE nut. If we want to live long and healthy, we need to stop the formation of this stuff.
    Though, who knows, maybe they will come up with something. I have a suspicion that Alpha Lipoic acid may do more than reduce its formation…because of some studies, though no one is saying this.

    They say these things help stop the formation of AGEs: Vitamin C, benfotiamine, pyridoxamine, alpha-lipoic acid, taurine, pimagedine, aspirin, carnosine, metformin, pioglitazone, and pentoxifylline. I don’t know which ones are most effective for stopping the formation of Glucosepane.

    But, of course, you are right about Glucose in as much as it is unavoidable, and necessary for nourishing the cells and several key organs including the brain. Hard to say if high dietary consumption has any affect beyond calories.

    And high levels of fructose appears to cause issues in the liver elevating triglycerides and “fatty liver” and all that entails.

    I believe we should stop subsidizing high fructose corn syrup, and end the tariff on sugar. Soft drink makers would just use sugar.
    Perhaps exaggerated, as we are talking just a few percent more fructose in HFCS. And reducing sugar in general is probably preferable.

  14. And there are some things that are surprisingly low in AGEs: corn oil (the best oil tested…who saw that coming?), coffee (you would think with all the roasting, but, no), eggs (scrambled on medium-low, poached or omelet, but I suspect boiled is even better, but they did not test), pistachios, tartar sauce, avocado (just because it is so low), low fat mayo, corned brisket (lower than raw beef!), liverwurst, lamb, tuna, reduced fat cottage cheese, reduced fat mozzarella, imitation bacon bits, soy burgers, Italian white bread, raisin bran (the bran flakes are lower than the raisins!), Froot Loops??, angel food cake, mustered (0), Pepsi (beats Coke even though it has more caramel color? Though both are very low).

    Worst drink by far was Enfamil. What is their excuse?

    The funny thing is it seems products that are advertised as either “low fat” or “low sugar” seem to lower the AGEs because you need both in there to interact. I never thought those things were anything more than gimmicks.

    It should be possible to make things that you have to blend by waiting to the last second to add the sugar or the oil, and bend that very little…and make less AGEs. Or buy those “low fat” or “low sugar” and add the fat or sugar, just stirring it in or blending a very short time. Of course, if they put chemicals in, those could hurt you, some other way.

  15. Yep… I know about the long term carb thing. 

    Right now I’m deleting another 20 lbs. At 1 lb a week, that’s Summer. 

    From what-all I’ve been reading, it seems that a biochemical basis for being choosy about actual complex-of-carbs you eat is wise.  

    Some sugars are polymers of (glucose-fructose)ⁿ oriented (n = 1 to 25).

    The small intestine hydrolyzes complex (n = 2, 3, 5) and simple (sucrose has n = 1) sugars to glucose + fructose units. Glucose is 100% problem free: the body’s energy transport molecule. Fructose, which can’t be used directly, has to make a pass thru the liver, to get rearranged.

    The liver, an ancient organ, reacts to the rearranged fructose units by producing large quantities of various cholesterols. 

    To battle inflammation elsewhere.
    And there is the problem.

    With the bizarrely high intake of sucrose and high-fructose corn syrup, our livers are handling dozens of times as much fructose than it would if just handling a real fruit load.

    So, in my case, ultra-high cholesterol production.
    A heart attack.
    A coronary artery stent bypass.

    Whacking the body mass is good. 

    Getting my daily carbs from carrots, rutabagas, parsnips, etc., is just fine.
    No sweeteners tho.
    Nor even the proxies: stevia, sucralose (bad), all the rest.

    Losing the “taste” for sweet in turn keeps away the bad but tastey stuff.
    Life choices.


  16. That 50-55% thing may be distorted by people grilling and otherwise cooking meat at high temperature, which makes carcinogens and AGEs: (foods)
    Quick easy reads for the nontechnical out there:

    I suspect you can get away with higher protein and fat if those AGEs are low. Stew, soup, chili, scrambled eggs, avocado oil, cooking with the bottom of the pan covered with water (replenish as it evaporates), and acidic sauces covering meat, if you do use higher temps, can reduce those AGEs.

    Not just heating makes these things heavy whipping/beating stuff does too.

    Some stuff is high in AGE’s that you would never guess or beyond what I expected: pine nuts, olive oil, canola oil, Parmesan cheese (by far the worst of the cheeses), cream cheese and feta cheese.

    Worst of the worst: bacon, butter, any “toasted oil”, roasted nuts, sesame oil (The toasted variety. If it is brown they heated it. Cold pressed is probably fine), but source does not say, cream cheese, margarine (does anyone still eat this terrible stuff), mayonnaise, hotdogs (yeah shocking), fried meat (deep fried is worse but pan fried is nearly as bad), grilled meat (can be even worse than frying), Big Mac (who could have guessed?)

  17. Congrats! I hope you plan to switch back to a normal composition of macronutrents. A study says optimal carbs is 50-55% for longevity.
    I bought the niagen from Amazon. I bought the 3 bottle deal. Seemed like enough to tell if it is working on me or not…but not so much that I would feel like an idiot if it didn’t. I have ordered other things from iHerb in the past and look at reviews from both sites for supplements. iHerb is faster shipping vs standard free shipping at Amazon. Though the Niagen did arrive very quickly. It was either 1 or 2 days later. Most of the rest of my order I am still waiting on. I am waiting for the fisiten to show up, because I want to combine that and a fasting mimicking diet. I think it might remove more senescent cells that way. Not sure if combining it is brilliant or not. If I don’t feel good, I will probably quit. I think it will be fine though. Strawberries have helped me in the past to feel better and may have helped me fight an ear infection I had had for over 30 years which always sapped my strength and obstructed my ability to accomplish things. Though, an old friend of my Mom did pray for me just a week or two before it began to clear up…so who knows. Started the frozen strawberry smoothy about a month before. Never thought I would hear much from that ear again…but now it works better than the other one…though it does still ring. I listen to music almost constantly now.

  18. There is one use for the “blow it to bits” scenario: really dreadfully LATE detection of a modest-sized impactor in the 0.5 km to 2 km diameter range. Just small enough to evade detection (un)serendipitously.  

    Such an impactor (1 km diameter, at 15 km/s) “only” has about 6.3×10¹¹ kg mass, 16,800 gigatons of impact energy. If left “big”, impacting terra firma, you’d get a crater some 25 km in diameter, and an ejecta ring some 200 to 300 km in diameter centered on the impact.  


    So, busting it up into millions of pieces, of which some are admittedly big on the tens-to-under-a-hundred meters in diameter, hopefully rapidly expanding outward with enough time to get “most” away from Earth impact, is a pretty useful concept. Even if most hit, the light show would be awesome, and there definitely would be hits of bigger chunks most-everywhere. Chelyabinsk level impacts.  Lots of glass broken. Minimized fatalities.  

    If the defense effort only has a few months, this option might be preferable.  

    Just saying,

  19. Read all your comments … OK.  Got it.


    Meteoritic impacts ought to generate quite a bit of compaction over aeon (multibillion year) timeframes. For whatever survives as a compact residual structure. 

    People tend to forget that a 25 km diameter (9.8×10¹⁵ kg) asteroid has a surface gravity of only 0.0042 N/kg (0.042% of one earth G), and a corresponding escape velocity of only about 10 meters per second.  

    This means that just about ANY particle that hits an asteroid is going to eject a substantial multiple of its mass away from the mother body, forever. Since impacts generally occur at a velocity on par with the orbital drift velocity at whatever distance they are away from the Sun. However, also it is the case that a broad cone of compaction will also occur.  Gradually whatever is left must by definition become :indurated:

    Just saying,

  20. Its working.  
    Biggest test yet, that was a Win…
    Went to visit brother in Massachusetts.

    You know the story: drinks! foods! wings! pizzas! cookies! more drinks!  

    I stayed away from all that, and kept as carb-free as I could figure out how to do and be polite when visiting his friends.  They were quite accommodating, too.  

    Got on the plane at 196, returned home for a 194 weigh-in.  Not bad, for a whole week of over-present straying-off-the-plan opportunities.  Not bad.  

    Yah… I’ve heard that about Chromadex and NR.  
    Which firm you order from?


  21. You are describing the process of induration. Jadeite is an indurated stone. Has negligible property differences from Cherts and Argillites. Its practically the same as indurated Rhyolitre or fine-grain Quartzite (which can be nearly as hard as Diamond).

  22. Trying to move an asteroid is different than trying to destroy it. At far enough out a small change in trajectory toward the direction of the Sun would be enough to miss. Even just slowing it, from far enough out, is enough. If you change the trajectory by even a fraction of a degree or the speed by a small margin, you could create a miss. Hell, maybe even detonate nukes just behind it to speed it up. All you need to do is make it miss.

  23. Don’t try to impact it and destroy it, detonate them at intervals at the right distance and try to alter the trajectory. We might have enough if we spot it far enough away.

  24. The best defense is early detection, Also, properly launched, nukes strapped to heavy lift rockets that you time to detonate adjacent to it, far enough out, maybe you can change the trajectory of an earth killer. You will be unlikely to destroy it. However, if you use enough large rockets to get to it far enough out, then fill them with the biggest nukes we have and detonate all at intervals to one side of it (think atomic bomb thrusts), maybe you can change a trajectory over a few months with enough rockets and nukes (which we have plenty of). Even with a 25km wide one, the thrust from 5000 nukes detonated to the side at the right interval should move it enough. Think one Falcon Heavy could send about 10-15 nukes to a Mars type distance. Each nuke has a small thrust that is timed to get the velocity to have them arrive at 10 km/s at 5 second intervals on the side of the asteroid opposite the Sun. Enough nuke pushes, maybe change its trajectory and pushes it toward the Sun.

  25. Indurated. Diamond is a indurated mineral. Compaction/pressure (think sustained high g’s if passing near a star and also tons of high velocity micro impacts), then think temperature (again a close encounter with a star). Those variables are all that is needed for induration to occur on a silicate based mineral.

  26. Indurated rocks are the hardest and toughest stuff on earth, so this makes sense. So, asteroids become indurated from high velocity cosmic dust, micro-meteorite impacts, and due to the g’s they pull at ties around larger cosmic bodies. They also gain further induration if they pull high g’s and gain higher temperature due to an orbital pass closer to a star during their history. That further indurates them.

  27. Call it “cosmic induration.” Think compaction due to high velocities.

    I have a bit of a geology background as a overall lithic tools expert. I know my stone.

  28. Jadeite is nice but too rare. Chert, Argillite, and Chalcedony all have a similar density and hardness to Jadeite, overall not much of a difference in toughness. Induration can do crazy things with minerals.

  29. Speed ,direction, rotation, shape, material and mass are most of the factors when considering asteroids. There is more to consider. Redirecting could cause fragments to hit the moon also. Which in turn could cause problems on earth to. If a large one pegs the moon first could send more debris to earth than we would care to imagine. Asteroid Gault now has a massive tail. A debris tail like that could block out the sun for us depending. There is a way to block against that though.

  30. Asteroid Gault was pegged by another asteroid. The only difference now seems it has a dent and a tail. Doesn’t seem to be redirected. Might depend on asteroid, some are more carbon base some more silicate. Some who knows. Heat and acid might redirect asteroids. Hydrofluoric for silicate rock. Hydrocloric for carbonate. Should be able to combine with rock to put into thruster. That way only have to take half amount of fuel other reaction in fuel is the rock. Thrust would be against constant pressure on the asteroid.

  31. Use a nuke? What did these guys do?

    We demonstrate this hybrid approach by considering the 5 km/s head-on impact of a 1.21 km diameter basalt impactor on a 25 km diameter target asteroid.

    A 1.21 km diameter basalt impactor at 5 km/s.

    m = ⁴⁄₃ρπr³
    m = ⁴⁄₃ × 3000 × 3.1415 × 600³
    m = 2.7×10¹² kg

    e = ½mv²
    e = ½ × 2.7×10¹²  × 5,000²
    e = 3.4×10¹⁹ joules (J)

    1 Mt = 4.2×10¹⁵ J

    e = 8 000 megatonnes

    You think you are going to use a nuke to blow it up when a direct impact worth 8000 megatonnes didn’t work?

  32. That still works. If Goat’s deflection project adds up to 3160 km/y, and that is a change in velocity, then a year later the asteroid is ~3000 km to the side of where it would otherwise be. Even if the probe stops working after a year that change in velocity will keep on existing, so 30 000 km to the side after 10 years and so on.

    Given our accuracy in plotting such rocks, we’d want to change the path by 300 000 km or more.

  33. You push … you don’t try to break (in fact you hope it hold together while pushing). The key is advance notice – 1 year it is too late, 10 years it is a huge project, 20 years it is doable with today’s tech (and a $T), 100 years … no big deal.

  34. How is the diet going Goat? Not eating paper and wood chips I hope. 😉

    I did a fasting mimicking thing for a few days. I think I will do another next week. Though that really is not for weight loss, just trying to clear out some bad cells.

    I am also taking some NR (Nicotinamide Riboside). I invested in Chromadex (CDXC) too, pretty cheap stock. Anyway, I did not “feel” anything, but my muscles do ache less after hard labor, and my bullet chess rating has gone up. The non-conscious mental processes seem to be of a higher quality. Better tactical pattern recognition, and better intuition. Probably worth it, though it is pretty pricey stuff.

  35. It’s all about applying as much delta-v to the asteroid as early as possible. Good scouting and predictions help a lot. Most strategies I have seen, revolve around early detection and then some way of imparting small forces over long time periods.
    That may work with asteroids because they orbit the sun much like the planets and are fairly predictable. Comets are the big problems because they have unpredictable orbits and come in much faster. We are unlikely to get more than 1 or 2 years notice for a previously unknown comet.

    I think there is a clever way to solve the problem by working up the delta-v in advance. We can accelerate matter cheaply, years in advance and store delta-v in clever orbits that will cover the most probable approach vectors. When an earth impactor is detected, we send our pre-accelerated matter away with a little final nudge.

  36. We need to get out there as quick as we can and harvest ALL of those moneyballs.
    Most dangerous ones first.

  37. It only makes sense to shatter them if you can do it early enough that almost all of the debris cloud misses the earth. Otherwise you’re just turning a slug into a shotgun blast.

  38. You may be overestimating how powerful nuclear weapons are. A world ending asteroid is a bit too much for even our entire nuclear arsenal to fully disrupt.

    Unless delivered to a precise location and hand detonated by a wildcatter, of course.

  39. Glass is kind of a special case in that regard, not actually being a solid, but instead a very viscous liquid. That means the particles can actually deform over time on the microscale, to increase the area where vacuum welding takes place. Even surface tension kicks in, over long periods of time.

    Anyway, a lot of the asteroids aren’t piles of primordial dust, but instead fragments of bodies large enough to have undergone compaction and melting. You should expect them to be about as solid and tough as any comparable volume of rock on Earth.

  40. Who is stupid enough to try shattering them. Any piece over 100 m could cause a devastating air-burst with the power of atomic bombs. What you want to do is nudge it out of a collision orbit.

  41. I think we need to get good data on the size of craters on a few thousand objects, record velocities and look at likely collision rates. Then computer models can adjust the hardness, compactness, and such to match the impact sizes observed.

    It would not be a bad idea to collect some small ones (say golf ball to bowling ball size) and vaporize them with lasers bit by bit until fully vaporized and learn everything we can about their composition.

  42. I am not saying you are wrong, it probably is happening to some degree, but the particles of whatnot on Earth are being constantly jostled by tidal forces, seasonal temperature variation, electrical movement from clouds discharging and vibrations from within the Earth and stuff we do.

    And while there is not likely to be any oxygen competing, leaving more chemically reactive surfaces in space, the contact particle to particle would be very stable, as the tidal forces would be trivial except with large asteroids, and heat in the asteroid belt would be very low.

    Also, usually when stuff in the lab welds it is all one thing and generally finely ground metals. I think it has something to do with the way electrons move around freely in metals.

    And what there is of the process you conjecture in space will probably not be a constant rate but a slowing rate, because of the constant and unchanging contact one particle to another.

    It is an attractive idea, but I think the effects would be small or asteroids would probably become beautiful solid crystals like snowflakes over eons.

  43. Ah, no. 

    The problem here is that you’ve succumbed to “blow it to bits and everything will be alright” syndrome.  

    Check out some of my other comments.  

    Also, a 25 km diameter asteroid, whizzing along at 25 km/s or so, (if spherical) has:

    r = 25 × 1000 ÷ 2
    r = 12,500 m

    ρ = 1.2 kg/L
    ρ = 1200 kg/m³

    m = ⁴⁄₃ρπr³
    m = ⁴⁄₃ × 1200 × 3.1415 × 12,500³
    m = 9.85 quadrillion kilograms (9.85×10¹⁵ kg)

    e = ½mv²
    e = ½ × 9.85×10¹⁵ × 25,000²
    e = 3.06×10²⁴ joules (J)

    1 Mt = 1,000,000 × 1 t of TNT.
    1 g of TNT ≈ 1,000 cal ≈ 4,186 joules
    4,186 × 1,000 × 1,000 = 1 ton = 4.2×10⁹ J/ton of TNT
    1 Mt = 4.2×10⁹ × 10⁶ 
    1 Mt = 4.2×10¹⁵ J

    e = 3.06×10²⁴ J ÷ 4.2×10¹⁵
    e = 730,000,000 megatons
    e = 730,000 gigatons
    e = 730 teratons

    Quite a a bit larger than gigatons. 
    Almost a petaton.  

    World shattering? Nah.
    But it would extinguish all life, for sure, on Planet Dirt.

    Just saying,

  44. I think I know the test they refer to. It is a Los Alamos Lab simulation wherr the nuke was a cue ball to the asteroid billiards and they all impacted and spread out. Up on youtube.

  45. I dunno, I think those numbers are overly simplistic. You aren’t moving it 1 mm/sec, you’re changing its velocity by 1 mm/sec/sec. Then you’ve got to take into account its orbit. It might be enough depending on the circumstances.

  46. If we have a year, it’d be tough.  If we have 20, it should be easy. If weeks, nearly impossible.  

    The most (ironically) attractive big-asteroid-nudging ideas so far have been to park a well-fueled ion-propelled space ship somewhere close to, but not landing on the naughty asteroid. Using the propulsion to overcome gravity, and remembering that whatever gravitational attraction the ship feels proximal to the rock, the rock feels proximal to the ship, gradually the space ship’s gravitation will vector the Bad Actor away from its collision course with Planet Dirt.  Might take hundreds of months. 

    And frankly, one need only nudge a Deplorable Stone a few few decimeters per second in order to miss Good Old Earth by many thousands of kilometers over a few years trying.  

    1 mm/sec × 60 × 60 × 24 × 365.25 
    → 31,557,600 mm/year
    → → 31.6 km/year.  

    Granted, that ain’t enough. 
    But it is 1 mm/sec. 
    1 dm/s would be 100× that, or 3,160 km/year.  

    Another alternative is to clamp a mass-thrower onto the Evil Elf, and chuck bits of the thing off at high speed by electromagnetic rail. A pair of ’em would also get the meter-or-ten per second vector achieved in a year or so.  

    Many ways.
    One goal.

    Just saying,

  47. That is silly talk. Cracked or not, if so much mass impacts the atmosphere, there are only two possibilities: either kinetic energy of impactor is deposited fully inside the atmosphere (finely shattered impactor), with inevitable multi-gigaton boom, or it is deposited partially inside atmosphere (smaller fragments) with a multi-gigaton boom, and partially inside planetary crust (larger fragments) with a surface multi-gigaton boom. Either way it is game over. So the only way to play and survive is prevention of impact. No matter how large an impactor, it must go boom in vacuum of space, not upon impact with our beloved planet. With that established, it is obvious even to simpletons what must be done: a fleet of space missiles with very large fusion devices. Upon strike of one after another, any size asteroid, and even more so comet, would be vapourised and scattered by thrust of expanding gas of its own superheated material. How hard is that to understand? Why choose between two certain ways of getting killed? Space rocks should be kept in space, and the only source of power at hand to make them so is nuclear fusion delivered in space, as much as deemed required, and then with safety margin of 100% or more. There is no spare Terra around, so a few more gigatons sent into space are very much feasible.

  48. Brian will appreciate this: there is a rather remarkable mineral called jadeite, which while being a pyroxene (NaAlSi₂O₆) composition, also has an unusually tough crystalline structure, mostly of interlocked fibers in a glassy matrix. The result is that it is HARD to work. Hard to break, chip or crush.  Makes for a good gross gemstone, actually.  

    I’ve noted in my hobby-horse geologic studies that older rock formations of even very loosely packed breccia are far tougher than later compositions of nearly the same stuff. Perhaps it is the millions-of-years presence of water that cements the particles of breccia together over the aeons, but there is some evidence that non-hydraulic (dry phase) particle-particle ambient temperature welding goes on, too.  

    For example, very finely divided glass powders, kept in hard vacuum, at first slop around when jiggled as if there were little binding atwixt the motes.  However, leave sealed glass tube of it sit around for a few decades (you know, ancient laboratories) … and some of the tubes’ glassy dusts will have welded themselves into a blob. Not very tough… you can touch with a feather and they’ll break apart.  

    But over not decadal, century or millennial but aeon time frames (billions of years) I would imagine that the primordial dusts that have accreted into objects the size in consideration of this article, would quite firmly weld. And once welded, tough they would be. Very tough. Like jadeite.

    Just saying,

  49. I guess if the asteroid is far enough away “nudging” (e.g., with a nuke) is easier to do than trying to blow it up? Seems to me there is nothing we can do about becoming extinct if an asteroid 25km in diameter comes our way.

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