Asteroid Bennu Has a Chance for Gigaton Impact Around 2175-2199

The Palermo Technical Impact Hazard Scale for asteroids is a logarithmic scale used by astronomers to rate the potential hazard of impact of a near-earth object (NEO). It combines two types of data—probability of impact and estimated kinetic yield—into a single “hazard” value. A rating of 0 means the hazard is equivalent to the background hazard (defined as the average risk posed by objects of the same size or larger over the years until the date of the potential impact). A rating of +2 would indicate the hazard is 100 times greater than a random background event. Scale values less than −2 reflect events for which there are no likely consequences, while Palermo Scale values between −2 and 0 indicate situations that merit careful monitoring. A similar but less complex scale is the Torino Scale, which is used for simpler descriptions in the non-scientific media.

On Jan. 27, 2020 scientists using a telescope on Mauna Loa in Hawaii spotted an asteroid that has been classified as a potentially hazardous asteroid. It is called 2020 BX12 and it passed within 2.7 million miles and will not get any closer pass over the next century. 2020 BX12 also has a moon. The larger rock is at least 540 feet (165 meters) across, and the smaller one is about 230 feet (70 m) wide. They appeared to be separated by about 1,200 feet (360 meters).

As of December 2019, two asteroids have a cumulative Palermo Scale value of above -2: (29075) 1950 DA (-1.42) and 101955 Bennu (-1.71). A further three have cumulative Palermo Scale values of above -3: 1979 XB (-2.82), 99942 Apophis (-2.83), and 2000 SG344 (-2.86). 25 more have a cumulative Palermo Scale value of above -4, three of them having been discovered in 2019.

Bennu has a cumulative 1-in-2,700 chance of impacting Earth between 2175 and 2199. It is named after the Bennu, the ancient Egyptian mythological bird associated with the Sun, creation, and rebirth. 101955 Bennu has a mean diameter of 490 m (1,610 ft; 0.30 mi) and has been observed extensively with the Arecibo Observatory planetary radar and the Goldstone Deep Space Network. If an impact were to occur, the expected kinetic energy associated with the collision would be 1,200 megatons in TNT equivalent (for comparison, TNT equivalent of Little Boy was approx 15 kiloton).

(29075) 1950 DA, provisional designation 1950 DA, is an asteroid, classified as a near-Earth object and potentially hazardous asteroid of the Apollo group, approximately 1.1 kilometers (0.68 miles) in diameter. It has about 5 times the mass of Bennu.

1950 DA had the highest known probability of impacting Earth. In 2002, it had the highest Palermo rating with a value of 0.17 for a possible collision in 2880. Since that time, the estimated risk has been updated several times. In December 2015, the odds of an Earth impact were revised to 1 in 8,300 (0.012%) with a Palermo rating of −1.42. As of 2018, It is listed on the Sentry Risk Table with the highest cumulative Palermo rating. 1950 DA is not assigned a Torino scale rating, because the 2880 date is over 100 years in the future. As of the 7 December 2015 solution, the probability of an impact in 2880 is 1 in 8,300 (0.012%).

The energy released by a collision with an object the size of 1950 DA would cause major effects on the climate and biosphere, which would be devastating to human civilization. The discovery of the potential impact heightened interest in asteroid deflection strategies. It would impact with about 10 gigatons of force.

The near-Earth object (89959) 2002 NT7 was the first near-Earth object detected by NASA. It was given a positive rating on the scale of 0.06 which indicated a higher-than-background threat. The value was subsequently lowered after more measurements were taken. 2002 NT7 is no longer considered to pose any risk and was removed from the Sentry Risk Table on 1 August 2002.

For a brief period in late December 2004, with an observation arc of 190 days, asteroid (99942) Apophis held the record for the highest Palermo scale values, with a value of 1.10 for a possible collision in the year 2029. The 1.10 value indicated that a collision with this object was considered to be almost 12.6 times as likely as a random background event: 1 in 37 instead of 1 in 472. With further observation through 2016 there is no significant risk from Apophis at any of the dates in question.

SOURCES – NASA JPL Center for NEO Studies (CNEOS), Wikipedia
Written By Brian Wang,

61 thoughts on “Asteroid Bennu Has a Chance for Gigaton Impact Around 2175-2199”

  1. Concur. Some people like to believe there is some definite dividing line between creatures that possess consciousness and those that don’t.

    Unfortunately for them, it is starting to look more and more as if (like almost everything else) there are only shades of gray between light and darkness, and any line we attempt to set is purely arbitrary.

    As a side note, there is no such thing as consciousness, the term is only valid used as part of the phrase “state of consciousness.” Oddly, enough, this is completely synonymous with “state of awareness.”

    Where it gets really boggling is when you start thinking about things like the Copenhagen Interpretation, Everett’s Many Worlds, quantum uncertainty, probability wave function collapse, free will, etc. in these terms.

    For example: If we hold to something like Everett’s Many Worlds hypothesis, or Schrodinger’s Cat, given that concept, it seems likely that it is an individual’s state of awareness that “splits” when it becomes aware of mutually exclusive states (and probably recombines should those states again become identical, as they never really separated in the first place, other than in our subjective world lines.

  2. We touched on this in an earlier article’s comments (

    The Moon’s contribution to the internal heat of the Earth is present, but insignificant at this point. Radioactive decay is why it is still molten, and that has a long but finite shelf life. (Which also means that planets around red dwarf stars don’t have trillions of years in which to develop life).

    Further, planets the size of Earth, that didn’t get a fairly large infusion of freshly forged radioactives, probably from a neutron star collision just before their formation, would already have cold interiors and would no longer have a protective magnetic field.

  3. You want a closed system. Far more complex, but much safer. You never know what kinds of gasses will be out there, lava flows, tsunamis, nuclear fallout from failed attempts to blow it up…

  4. Sure, we can bust it up. Vaporize it? No. Knock it off course at a couple days from impact or less? No. Busted up however, it does not mater if it hits. The atmosphere will take care of it. The explosions in the air could do some damage to trees buildings and such.
    But something like what took out the dinos (10Km)? No.

    I envision immense caverns that are attractive. You won’t just be looking at rough rock surfaces in dim light in a cold, 100% humidity pit.

    You can mimic any region on Earth and always have great weather.

    It would be more like the holodeck, only it just runs the same program, and the trees, grass, and many other things are real.

    No solar skin damage, no natural disasters, no crummy weather (but maybe a little variety), no termites, ants, mice, rats, weeds, mosquitoes. There will be well engineered transport systems, grassy parks, zoos, arboretums, stadiums…

    However, if a rock is coming in just a few years and it is a dinobuster, we will have to make less attractive shelters enough to accommodate everyone, and lots of animals and plants for the future. I don’t anticipate conditions being unlivable for decades…though that is possible. Assuming we don’t have nuclear fallout everywhere from unsuccessful attempts at destroying it, the dust/ash should fall out of the air within a couple years. Or at least enough to breathe fine. If things got really cold then we will have to build domes and better underground stuff. Domes later, might still be some rocks

  5. I am fairly sure we can make a big enough nuke (or nukes) to not only nudge the orbit of, but also completely vaporize a 490-meter diameter rock.

    I really do not want to live in an underground shelter for decades, thanks anyways. Someone would be sure to go on a murderous rampage after watching Frozen for the 1000th time.

  6. There is no conflict between these non-human examples and the normal forces of selection. The extreme example would Jane Goodall’s discovery that chimps can be reperessed/neurotic. But those chimp examples are because of *natural* things, early maternal death and such. In humans, these things plus the living, evolving rituals called “The System”, by which as much pain as can be handled is inflicted, until the host(us) dies or fails to reproduce successfully. A similar dramatic difference in humans is the evolved response to the System’s oppression, what I call *love* for want of a better word, and it is beyond but built upon your examples. It will remain once the System is destroyed, by the way.

  7. Again, these factors are not exclusive. Janov presents very hard physical evidence that birth trauma and other trauma at both earlier and later times has a very large impact. Canada has a program to get micro elements into poor diets, very cost effective, very boring for news.
    “children can recover better from than adults while probably even feeling that pain more acutely” is indicative of the resilience of children, but also the hidden nature of repression. They seem to have recovered, but they carry a hidden burden. Adults have a balanced maturity, so the parts of the brain do not overwhelm less mature parts with overload, which leads to repression. An overloaded adult will pass out, but not repress further. Unless experiencing electoshock.

  8. Ok, it may hit the Earth in 100 years. So what? Let’s get to the important question considering it is a NEO. How much is it worth compared to the cost and risk of capturing it?

  9. Love is something many mammalian mothers exhibit, and individuals of many species can apply this in other circumstances. Some of my cats love me and not just the food I feed them or the petting. Some are certainly more self-centered. But a few of my roughly 20 cats, I am convinced, actually love me. And many like each other too often licking each other. I had a cat once who carried a feather everywhere she went. She was absolutely never without this thing. I think there was some motherly drive involved. And she had a friend that was always with her that was patient with her always picking up her feather before they wandered off to hunt bug or whatever. Friendships and love are certainly not just a human thing.

  10. Iodine is not the only relevant nutrient. Having a very small amount of lithium in the water is also beneficial: Requiring 150 micrograms per liter in all bottled water and in the city water supply could be very beneficial.
    And heavy metals such as lead, mercury, cadmium, and arsenic damage impulse control IQ and other factors that increase crime and abuse. But I have gone into this many times.
    There are also genes that influence anger, and aggression:
    I also suspect there are genes that make some people enjoy the act of killing. Makes sense if we are a hunting and gathering species.
    The desire to dominate others I strongly suspect also has a genetic component.

  11. Abuse is certainly a factor. Physical trauma…I think children can recover better from than adults while probably even feeling that pain more acutely. However, nutrition is underestimated. I think the reason Japan has so few homicides is not the lack of firearms and a general training of children to treat people with dignity and respect…though certainly that is a factor. I think it is iodine intake by their mothers before and after birth, and high iodine intake in the first few years of life. This is mostly from including seaweed in the diet. Cod can also have iodine, but at much lower levels, nonetheless cod might result in lower crime where they eat more cod:
    We know that having very little iodine during pregnancy and beyond results in cretinism. This is a stunting condition but results in people with very little ability to tell right from wrong (feelings associated with societal norms if you prefer). I don’t think it is a stretch to think that more than the minimal amount most people in the world get, can result in people with very well developed consciences…and result in lower crime.
    It does not explain the entire difference between populations but when there is a lot of fish consumption there generally are less homicides.

  12. Rubble piles you bag ’em and tag ’em. Then its a contained problem.

    By “bag” I mean things like a carbon fiber net to keep stuff from floating away. Then you can anchor whatever you want to the net.

  13. I think it will take longer than that to run out of stuff to mine. How fast will space mining grow?

    The lunar regolith (surface layer of broken rock and dust) will last 17,000 years if mined at the combined rate of coal, iron ore, and other metals (17 Gigatons/year as of 2016). The largest single near Earth asteroid, 1036 Ganymed, would be another 2000 year supply.

  14. And on a broad overview, humans have been forced to evolve a thing I call *love* to counter the quickly changing System. No other known being has had to do this. It is why we want to protect the Earth, beyond mere self interest. Why we study science. And especially, why we love our children far more than normal evolution required (Thanx Gail King), if allowed by the System.

  15. “some genetic modification may be required”. For ~seven million years, the coevolution of our reproducing rituals, The System, and those few surviving it, has made us quite different from our chimp-Bonobo starting point. Big brain to not go crazy under the load. Infantile sexual stuff, to take advantage of repressed infantile need as a bonding mechanism. No fur to allow infantile touch need, needing to be assuaged. Don’t be proud if you are a modern human.

  16. We agree on your first para, that’s what I indicate when I say they are not exclusive: both are (potentially) right.
    And I mean power as in control, not energy.
    I agree with your prescription to prevent forming power addicts, basically, prevent child abuse. But the mechanism is actually much more specific, and was only fully avail for examination when Janov accidentally discovered repression, the complete denial of overwhelmingly traumatic experience. Early Freud and esp Sandor Ferenczi (both as described and presented by Jeffery Masson in “The Assault on Truth”) had the right idea, but not the experiment: the Primal. Janov had no idea of this, but had the actual experiment. By observing the release of the repression, done by experiencing the trauma (not thinking about it differently-EXPERIENCING it), science wins out. Turns out the birth experience is the biggie, and the easiest to correct. Symptoms of this curable condition abound. Watch the news!

  17. I’m seeing 1 million years to degrade in landfills which is the ideal situation. That still gives plenty of time for space dinos.

  18. effective programs to reduce drunkenness, and other inebriation that leads to violence and abuse, good counselors/psychologists with easy/cheep/free access, possibly minor reductions in free speech to reduce verbal abuse of individuals and groups especally hate speech, and gleeful/sadistic derision. And it is likely some genetic modification may be required. And beyond all that, perhaps a way to identify and make it clear to others in relevant situations the dangers of this person. Perhaps outright block some people from ever having authority over others.
    If this seems a little strong, consider that our technological power is increasing and a leader’s ability to take overwhelming control is only increasing.

  19. Yes. Maybe it was hidden a bit, but that is part of my point. It is not sufficient to have a space program, it must be developed to the point where colonies can grow and flourish on their own. They don’t have to be alone, they can cooperate and trade with one another and with Earth but if there is ever a catastrophe that knocks one or the Earth out, we need to be able to still stand on our 2 feet in all those places.
    And we need self-sufficient colonies on Earth too: underground, under dome (arctic/antarctic), under water, floating, possibly in the atmosphere, under the ocean, under one another under ground…

    Did you mean “power addicts” as in barbaric leaders or “power addicts” as in energy guzzlers? The second kind is much easier to deal with than the first. The second type can be addressed by making machines that are more efficient, and by making the lazy path the most efficient one. By that, I mean, for example, making fast food (even healthy stuff) preparation more energy efficient and quickly and efficiently transported so people don’t waste time and energy cooking their own stuff. Or there may be more efficient personal transport systems that are very quick. People will use them because they are quick and leave the car at home. Or maybe they will telecommute, if you get the technology right.

    The first will require good prenatal nutrition, low/no neural toxins, good training of parents and would-be parents, means of easy escape from abusive relationships, cont.

  20. No doubt we can clean up some junk. It won’t be cheap though…at least at first. It would be helpful if we could recycle/reuse it in orbit, to help pay for it. It would also help if we had a designated very compact areas for satellites to retire. Geostationary satellites do have a place they are supposed to go, but it is just a higher orbit rather than somewhere specific in that orbit.
    If the stuff was going to specific areas you could have robots there to physically weld them together into a sort of lattice. Components can then be removed as required to build new stuff. Maybe you don’t have to launch complete satellites, just some of the electronics that can fit in an existing derelict satellite, and some propellant.

  21. 1200 megatons is ~ 1 order of magnitude larger than the biggest ever nuclear weapon test.

    So, unless the Tsar Bomba was unreasonably close to some sort of tipping point, it isn’t a world ender. A very bad day for the local region. But other countries should be OK.

    Hmmm… let’s look up big volcanoes.
    Krakatoa 1883 – estimated at 200 Mt
    Tambora 1815 – 33000 megatons!

    OK. This asteroid would only be about 1/20 the 1815 Tambora eruption. Now that messed up the weather world wide. Crops failed in Europe and China. But a couple of years later everything was back to normal except in the immediate vicinity (which was, of course, destroyed).

  22. On the other hand, launching 10 000 satellites per year means a significant launching capability.
    Which means a set of space based telescopes giving very accurate mapping of all the objects in our solar system.
    It also means the capability to, fairly cheaply, get large, powerful, probes out to any worrying object, study them, analyse their structures, and eventually do something about their trajectories.

  23. You are forgetting that if we start launching 10,000 satellites a year, in 100 years there could be 1,000,000 satellites to dodge to get close enough to do anything…and that is assuming several have not already slammed into each other and no other escape missions have ended in obliteration. It could be the new smog. Hundreds of millions of satellite bits.
    This is one of the reasons we need colonies that can operate independent of Earth resupply. We may need them to protect us from things like this if escape trajectories are no longer possible.
    It also suggests some collection of space junk will become necessary in the future. That level of cooperation would be unprecedented…hence my projection of significant risk of this smog.

  24. There is a lot more to this, but suffice it to say these continents may be with us much longer than people are projecting today.

  25. If you study geology, the dogma is “constant predictable plate movement and repeated cycles of renewal”. However, if you study geology in more detail, physics, astronomy and other sciences you get a very different picture. The convection of magma is a function of the input energy from tidal forces and and nuclear decay. And it is also influenced by heat conduction of the oceanic plates. These things are not constant. The Moon is moving away from the Earth imparting less and less tidal energy. Every year it is about 1.5 inches further away. Doesn’t sound like much but it adds up when you are talking about timescales we are talking about. And, yes, even then it is not huge, but it does combine with these other two: there are 4 Actinide alpha decay chains. Because of the age of the Earth anything that was radioactive when it was formed and decays into something stable in that step has already done so. The stuff that is radioactive today is moving along these chains of transformations to lower mass. These things are in 4 chains. Because of the time involved one of these 4 is already extinct and has imparted all the energy it will ever impart to the Earth interior. The other 3 are also well on their way down the later and generally give less energy as time goes on.
    Uranium is already as rare as gold.

  26. That was my first thought – though we have 150 years to simply deflect this thing by a tiny fraction of one degree. By 2175, teens with pilot’s permits should be able to do that.

  27. ‘to address problems here on Earth’ can be done with O’Neill plans, not Mars fantasy. An important distinction!

  28. They won’t have power over those of us in Space. Terrifying for power addicts. And we can ONLY solve Earth problems by going to Space, more true the longer term is considered.

  29. Have not read that. Comet theory I heard is from so called *chevrons* of ocean debris washed into E Africa coast, which led to discovery of crater prob from comet, in Indian Ocean, hit right before worldwide flood stories arose, about 5,000 years ago.

  30. Yep. I read Larry Niven and Jerry Pournelle’s Lucifer’s Hammer, too.

    As I recall, even after the comet hits, then you got all those pesky cannibal armies to deal with.

  31. Working backward, with the average velocity of interplanetary lopers, of mmm… 20 km/s or so, each cubic meter at density 1,200 kg/m³ has an impact energy of

    Ek = ½mv²
    Ek = ½ 1,200 × 20,000²
    Ek = 240,000,000,000 J … divide by 4.186×10¹² J/kT-TNT
    Ek = 0.057 kT-TNT per m³ of impactor.

    OK, with that out of the way, now we can work backwards:

    1 GT-TNT 
    = 1,000 MT-TNT 
    = 1,000,000 kT-TNT
    So, 1,000,000 kT ÷ 0.057 kt-TNT/m³ = 17,500,000 m³


    vol = ⁴⁄₃πr³, then 
    r = (¾ vol/π) to the ⅓ power, now sub in above
    r = 160 m
    diameter = 320 m

    There we are, the impactor would be anywhere from 250 to 380 m diameter. Pretty big! As a ‘gravity check’ (pun intended), let’s work with the Chelyabinsk doodad, estimated (early on) to be 60 ft diameter, yielding 500 kT:

    vol = ⁴⁄₃πr³
    r = ( ½ × 60 ft × 0.3048 m/ft )
    r = 9 m

    vol = 3,000 m³
    m = ρ vol
    ρ = 1,200 kg/m³
    m = 3,700,000 m³

    Ek = ½ mv²
    Ek = ½ 3,700,000 × 20,000²
    Ek = 0.73×10¹⁵ J … divide by 4.186×10¹² j/kT-TNT
    Ek = 180 kT-TNT

    That’s sufficiently close to the much-more-well-refined 500 kT announced later on, that it at least proves the math “is about right”.

    Putting a 300 m-diameter object in perspective, it’d dig a crater about 15× or 4.5 km in diameter. That’s one big pit.

    BUT … ain’t the end of the world, either.
    Not even close.

    ⋅-⋅-⋅ Just saying, ⋅-⋅-⋅
    ⋅-=≡ GoatGuy ✓ ≡=-⋅

  32. In a hundred years we will probably be crying because there are no near earth asteroids left to mine and we will have to go to all the trouble of mining the asteroid belt or Mercury.

  33. If our ancient ancestors had thought about ‘solving everything here in the Savannah first’ before emigrating, there wouldn’t be any humans anymore.

    Most big human problems aren’t ever solved, they simply become irrelevant by change or find an unexpected solution from expanding our horizons and settling new frontiers.

    And yes, people in power are a threat, by ever pushing boneheaded legislation, a process which seems to have no end and that will require an eventual re-foundation of the constitutional order (when law becomes cancerous and unknowable by human beings, and when everyone is a felon by some obscure law or another).

  34. Subduction does not always happen, as Venezuelan highlands show. The question was whether “we’ve had civilizations on earth” before. Any that used glass we would know about. Now, you are not going to get cut walking on the beach by it, either.

  35. What I worry about are folks who get into power and stop our even going to space, ‘to address problems here on Earth’. That essentially was the rationale behind cancelling Saturn (that, and declining public interest) – but yet there were a LOT of highly trained folks thrown into unemployment because the feeders to the Space Program lost contracts.

    That we ended up in a recession wasn’t much of a surprise…

  36. Over the next 150 years someone is going to mine that thing down to nothing.

    But, before they can, someone else will probably demand an ecological impact study.

  37. Not so much. Glass does weather, slowly, and then you’ve got to figure continental subduction into the mix. 10-100 million years or so – it won’t be an issue.

  38. Wouldn’t be surprised if the impact chance plummets to an insignificant level over the next few decades or years, as we get more observation data. It’s already pretty low.

  39. Not yet, quite recent! 2015. Wiki sez “Cloud Ark must be self-sufficient for 5,000 years”, so is clearly not following O’Neill. Thus scarcity assumption, exciting story, but example of perspective I’ve been fighting for over 40 years.
    Interesting mention of epigenetics: ” Moirans who can undergo epigenetic shifts, radically changing their bodies in response to new environments” Janov way all over that. Check it out.

  40. Human impetus towards space continues, with different forms and methods, but we launch more stuff to space every year than the last. And there is no reason to believe this will stop.

    If all goes well and the gears of history continue turning as they have, there will be a lot more human presence in the Solar System by then (not necessarily human presence, but still human made stuff).

    And a lot more means to send something over there (gravity tractors, solar sails, propulsive laser ablation) that can deal with such a menace, even if it is relatively slowly.

    Although if Elon Musk’s dreams turn out to be correct, people will be doing vacations on the Moon and Mars, and moving Bennu won’t be more relatively difficult than other contemporary big engineering projects are nowadays.

    But if we are unlucky and society regresses for whichever reason, then humanity of that time could have quite more to worry about (and not just about Bennu).

  41. And we’ll be well established on Mars assuming no incredibly unlucky space events or self destruction. The space dinos are fun to think about. If you imagine a rock inducing an extinction level event today (something humans don’t recover from) nearly all traces of our civilization would be gone in barely 10’s of thousands of years. Metals, plastics, nuclear waste, dams, the strongest deepest bunkers… everything. Given how fast we’ve popped up it is quite possible (however unlikely) that we’ve had civilizations on earth before that rival or exceed our own and have had their own space based extinction level events.

  42. Comets can come in fast and unseen until too late, and they leave far less evidence as craters. Some argue they are far more dangerous than we think.
    Anything we accidentally change can likely be changed again, especially if we are already mining there. Intentional redirect seems more of a problem.

  43. On this particular rock, we better be able to do something in 150 years, or we don’t have a Space program. There are other rocks, however, and gamma ray bursters, and solar flares, on and on that would benefit from deep Earth shelters, but we should also scatter the target (us) around in Space too. They are not exclusive at all. Fewer power addicts would be nice also.

  44. I am not worried about these. I am more worried that as we mine in space and such we will accidently redirect things that may hit later. The stuff that we have found out there is pretty low risk. There could be stuff we don’t know about with much higher odds. However, I don’t think there are any that we would not discover that are just a few years away. I think, we would at worst, have 20 years warning for anything big.

  45. How do you know they did not have a space program? Have we searched the whole Moon for other flags? 😉
    You need more than a space program…our non-flapping flags are not going to help us. Even our nukes would be useless. The rockets may as well be delivering BBQ sauce, or speeding tickets.
    Best bet is deep bomb shelters capable of supporting people (or dinos) for decades if necessary. That means geothermal/nuclear power, a good well, and a wide variety of technologies for recycling, manufacturing, growing and storing all sorts of stuff. And you need them all around the planet, because by the time you know where it is going to hit, it may be too late to build shelters far away.

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