The biggest threat to humanity, far bigger than global warming/climate change, is about to get bigger, much bigger
A press release from some former NASA astronauts on the current asteroid impact threat to earth, based on data on in-atmosphere detonations since 2001, gleaned from a nuclear weapon detonation detection system has yielded some startling numbers.
The threat is 3 to 10 times higher than previously predicted. The data will be presented at the Seattle Flight Museum, Tuesday April 22, at 6:00pm PDT.
Just last night, another fireball was seen over Russia, caught on a dashcamera. See video.
Now it becomes apparent why this press release is important.
This Earth Day, Tuesday, April 22, three former NASA astronauts will present new evidence that our planet has experienced many more large-scale asteroid impacts over the past decade than previously thought… three to ten times more, in fact. A new visualization of data from a nuclear weapons warning network, to be unveiled by B612 Foundation CEO Ed Lu during the evening event at Seattle’s Museum of Flight, shows that “the only thing preventing a catastrophe from a ‘city-killer’ sized asteroid is blind luck.”
Since 2001, 26 atomic-bomb-scale explosions have occurred in remote locations around the world, far from populated areas, made evident by a nuclear weapons test warning network. In a recent press release B612 Foundation CEO Ed Lu states:
“This network has detected 26 multi-kiloton explosions since 2001, all of which are due to asteroid impacts. It shows that asteroid impacts are NOT rare—but actually 3-10 times more common than we previously thought. The fact that none of these asteroid impacts shown in the video was detected in advance is proof that the only thing preventing a catastrophe from a ‘city-killer’ sized asteroid is blind luck. The goal of the B612 Sentinel mission is to find and track asteroids decades before they hit Earth, allowing us to easily deflect them.”
In partnership with Ball Aerospace, the B612 Foundation will build, launch, and operate an infrared space telescope to find and track the hundreds of thousands of threatening asteroids that cannot be tracked with current telescopes. See the mission pager here
Read the press release at:http://b612foundation.org/news/b612-press-conference-on-protecting-earth-from-asteroid-impacts/
h/t to reader “Mac the Knife”.
Thanks, A. But I’m not scared of asteroids.
As a reference:
A New Count of Potentially Hazardous Asteroids – NASA Science (May 16, 2012), at
http://science.nasa.gov/science-news/science-at-nasa/2012/16may_pha/
I’m all for spending a little money on identifying and tracking potentially hazardous asteroids, if we can get to the point where we know where they will hit. With sufficient warning, people might have some time to get the heck outta the way. That’s a whole lotta ifs though, and I’m not sure how much money would need to be spent to be able to predict an impact site.
It sure makes that 350 PPM thing look insignificant. It just goes to show how
important it is to have an atmosphere. The Moon is riddled with impact craters,
while our atmosphere defends us against all but the worst of threats.
It would seem to me that regardless of mass, the greater threat is an air-burst
rather than an actual impact, for the same reason a nuclear air burst is more
devastating than any similar device detonated at ground level.
While an event over a major population center would kill a whole bunch of people,
an air burst would mitigate any “Nuclear Winter” scenario. It would cause damage
over a wider area, but with less atmospheric impact.
Agfosterjy
I did not say the probability of meteor impact P = 1. I mean the probability is higher now than in other periods. Let’s estimate the value of P = probability of big meteor impact this century. Using the observed frequency of once every 10 million years, we can assume the function is a random variable with central tendency to cycle every 10 million years. Since random variables follow the normal distribution, we can assign 2-sigma deviation = 10 million years. From the z values of the normal curve, we can calculate P when x = 100 million years or more and dx = 100 years. P = 8 x 10^-6 or one in 125,000.
How likely is that? Let’s compare it to a natural disaster like typhoons. Haiyan was reportedly the strongest typhoon to hit land. It killed over 6,000 people in the Philippines. It is one of the most typhoon-hit countries in the world. About 20 typhoons hit the country every year. The typhoon mortality rate in the Philippines is one in 135,000. Therefore, earth is more likely to be hit by a giant meteor than for a Filipino to be killed by typhoons.
Russia has had another light show, over Murmansk.
Gamecock says: April 20, 2014 at 5:23 am
“over 90% of the near-Earth objects larger than one kilometer already discovered”
“Curious. How can you count that which you haven’t discovered?”
Start counting, and cataloguing. At first all objects are new, then you will be rediscovering objects already catalogued. Your graph of NEOs larger than 1 km against time will rise steeply at first, and then the slope will decrease. Eventually you will reach a stage where you can fit a curve to the rate of discovery. With this curve you will be able to calculate the level of the asymptote to which the curve is rising – this is the total number of NEOs fitting your parameters. Presumably those who are doing the counting have fitted such a curve, and reckon that on their calculations the total number aklready discovered is more than 90% of the asymptote level.
Mind you, they could be wrong, but I would say their chances are better that several orders of magnitude that the CAGW people are right.
Correction: I was looking at one-tail z values. It should be two-tail. The probability of giant meteor impact P is one in 62,500
Why the urgency to prepare for asteroid or comet strikes of low probability that we can do little about and of which we’d at least have some reasonable advance warning when we aren’t doing anything about catastrophic solar EMP events the probability of which appears astronomically higher, of which we’ll only have a couple of days’ warning, and for which we could prepare?
George Howard over at CosmicTusk.com suggested some of us who’ve been looking at these things pop over here to some clarity.
The first thing to say is that “multi-kiloton” is a bullsh**t term. Almost all of those were VERY low kilotonnage. A 1-kiloton object disintegrating (NOT EXPLODING!) high up near the top of the atmosphere is not in ANY WAY remotely city killers. Neither is a 50 kiloton one – as Chelayabinsk showed last year. So, we can rule out 50 kiloton “explosions” high up in the atmosphere right off the bat. Even Tunguska in 1908 was basically about a 10,000 long ton body that entered the atmosphere (20,000,000 kgs) – and it knocked down a LOT of trees, no easy task, and it MIGHT be called a city killer.
As to the size of Tunguska’s blast and Chelyabinsk’s blast, almost ALL reports – including scientific papers – talk about the size of blast as the object entered the atmosphere. But as the meteors crossed the sky (see following) over 90% of the objects get ablated away. And the buggers do NOT clarify the BEFORE and AFTER conditions – IMHO an intentional exaggeration to draw attention and funding (VERY similar to global warming exaggerations). Thus, Tunguska is claimed to be a “megaton” sized air blast. Chelyabinsk is claimed in almost ALL reports to be a 500-kiloton blast. Those are based on size at entry, not size at “explosion.”
HOGWASH. Reduce both figures by 95%.
Tackling some comments, one by one:
@MarkG April 19, 2014 at 4:01 pm:
The rest of the people here should know that this is basically correct, though the first part is not exactly true. Because the Earth’s atmosphere ablates (melts and then vaporizes) about 90% of the material of incomiong objects, not so much is left, and – as Chelyabinsk and Murmansk and many other bollides have shown, they basically disintegrate high up in the atmosphere. Chelyabinsk was 25+ km up, and only about 10% of the reported 500 kilotons was still intact when it did the big flare (disintegration). Without radiation, we could have Chelyabinsks all over the planet and all we would get is a lot of broken glass and cuts. That does not exactly constitute “city killers”. Chelyabinsk’s remnant meteorite weighed only 654 kg out of 7600 long tons (13,200,000 kgs) at atmospheric entry – a reduction of 99.5%. THAT is what we have, folks – a force field called the atmosphere. I will assume that the meteorite was 50% of the mass that flared (the big flare), so basically it was ~95% evaporated before that flare.
And, in reality, that meteor did disintegrate over uninhabited land, though several villages were very nearby, especially Yetkul (Etkul) and Korkino. So the point is very well taken that the vast majority will miss cities.
@YouSoWould April 19, 2014 at 4:04 pm:
Before 2007 we all thought that, too. However, google the “Younger Dryas Impact Event” and you will find much about a VERY recent impact/extinction event – well inside the time of Man. Also, visit http://www.CosmicTusk.com – linked in the right-hand column here for articles, paper links, and commentary.
Well over 30 scientists – in over 24 papers – are now on record as arguing that at 12,800 years ago an impact event occurred in North America – taking out perhaps as many s 32 species and also perhaps wiping out Clovis Man. Much forensic evidence has turned up on four continents that backs up their thinking. There is a small cadre of ill-informed and very conservative nay-sayers who keep on cherry picking the forensic evidence for flaws and who have come up with very little counter evidence. Most of what the contrarians have asserted has been shown to be categorically WRONG and poorly done science.
The main solid argument against this impact event and its effects (the main one being the T+Younger Dryas stadial – the very last real ice age and one that has stumped biologists and climatologists for quite some time) is this: NO CRATER has been found yet. Why that should be an argument after only 1,2 or 7 years one cannot fathom, because it took 10 full years for that 65 million dinosaur killer’s crater to be found – and that wasn’t even by a scholar, but by an oil industry geologists who happened to already know about the evidence for the crater. THAT crater was 300 km across. The mammoth killer of 12,800 years ago should be somewhat smaller and appears so far to be in the Great Lakes region – but, nope, not found yet. But nobody is panicking about the lack of a crater yet. People are on it. Since it is smaller, it should take longer to find. In the meantime the forensic evidence keeps piling up.
…more info in the next comment from me…
I think I mentioned decades ago, living on a small farm near Tamworth, I was moon bathing (it is very refreshing) when the full moon is out and it is warm. I looked up to wonder at the skies, spotting the occasional satellite and suddenly there was a beautiful bomb burst (like a firework). It only lasted a few seconds. I wonder what it was, surely not the Russians (LOL) exploding bombs up there or a UFO being shot down? I asked someone years later what it was. He said a meteorite exploding when hitting the atmosphere. It must have been quite big though to make sure a display.
Kiloton is a unit of measure for energy release. The Chelyabinsk event is estimated to have released approximately 460 kt of energy. This is mostly derived from air blast over pressures and the area covered. They used consideration of the altitude where the energy was released and well understood scaling laws from Nuclear weapons testing. Using altitude of energy release and overpressure area they resolve back to the equivalent explosive energy required to produce the same results under the same conditions.
http://adsabs.harvard.edu/abs/2013GeoRL..40.3732L
http://newsroom.ctbto.org/2013/02/18/russian-fireball-largest-ever-detected-by-ctbtos-infrasound-sensors/
With 7200 buildings damaged and 1491 people injured from an event that occurred at an altitude of from 29.7 – 23.3 km and 40 km south of the city clearly shows that if it had been displaced only slightly so the peak energy release occurred directly over the city and at a similar or lower altitude it could very easily have caused “city busting” damage to most metropolitan areas of the world (depending some on the quality of construction and other factors).
It was clearly a wake up call that these events are very possible. The Tunguska event leveling of trees demonstrates a huge release of energy. Tree blow down occurs at blast over pressures that are capable of totally destroying common residential structures. To achieve 90% blow down of coniferous forests you need effective wind speeds in excess of 140 mph which occur at blast over pressures of approximately 4.2 psi. Common residential construction is totally destroyed as a habitable building at between 3.5 and 5 psi blast over pressures. In short a modern city exposed to the same air blast as Tunguska would have effectively had all the conventional wood frame buildings destroyed, all windows blow out, all exterior doors blown into the building and many interior walls and roof trusses shattered over the area where total forest blow down occurred in Tunguska. The same winds would have also taken down most of the electrical distribution lines and poles over the same area.
@Larry Cullen Ledwick:
“With 7200 buildings damaged and 1491 people injured from an event that occurred at an altitude of from 29.7 – 23.3 km and 40 km south of the city clearly shows that if it had been displaced only slightly so the peak energy release occurred directly over the city and at a similar or lower altitude it could very easily have caused “city busting” damage to most metropolitan areas of the world (depending some on the quality of construction and other factors).”
Not quite so. The explosion was almost directly over Yetkul (Etkul) and Korkino, and nothing like city busting damage happened to them.
As to your rebuttal of my air burst assertions, your first link doesn’t work, and the second one doesn’t even mention kilotons or megatons. THAT one (which I read way back in Feb 2013) talks about the moving object and its significant effects on infrasound detectors. They say they used the data to determine the flight path. Though the article talks about the “explosion” as being the largest ever detected, there is nothing in the article reflecting your own assertions about determining the blast force. They make a big point about it being a moving infrasound event. So it is an open question from that article as to where the 500-kiloton number came from. All articles I’ve ever read about the event (and that is many) talk only about the orginal size and the 500-kilotons. No mention has been included in any of them about the diminishing size of the object. If you have any, please point me to them. I am all ears.
Perhaps the bad link does have something such as you assert?
More alarmism- this time about “asteroids” which is a misuse of the term. Meteorites are not asteroids. Depleted comet heads are not, either. This post just stinks. There is a money angle to this, you can bank on it.
To see the abstract you need to cut and paste the entire link, it has imbedded dots which wordpress improperly parses to break the link.
The key sentence in the link abstract is:
A preliminary estimate of the explosive energy using empirical period-yield scaling relations gives a value of 460 kt of TNT equivalent.
The book “The Effects of Nuclear Weapons” Samuel Glasstone and Philip J. Dolan published in 1962, and 1977 gives detailed discussion of how the blast effects scaling laws were developed during the early nuclear testing series. It also discusses the characteristics of air blast and air blast damage and how that is modified by the altitude of the explosion.
Damage range varies at the cube root of the energy release. The Chelyabinsk event with its documented structural damage is a valuable bench mark as it is one of the only significant events that has occurred near a modern built up city. With its low angle of approach the blast effects were spread over a considerable ground track. If it had by circumstance been a near vertical entry angle the same energy would have been concentrated and focused into a local area.
What is more important though is how air blast characteristics vary with altitude. The Chelyabinsk event occurred at very high altitude where the energy yield is poorly coupled to air blast. If the structure of that bolide had retained its original form long enough to penetrate to a lower altitude before it underwent primary break up the energy released would have been much more efficiently been converted to blast winds and over pressure. At low enough altitude the blast wave interacts with the ground reflection doubling the blast over pressures near the ground creating a near vertical wall of reinforced blast pressures called the “Mach front” or “Mach stem”
When the following ref talks about “scaled heights” they are referring to these scaling laws described in detail in “The effects of Nuclear weapons” where they determine a relatively simple scaling relationship between energy release and damage effects compared to a reference yield of 1 kt of TNT equivalent energy release at some fraction of height of burst or radial distance. These scaling laws can then be used to find the effective energy release from a damage effect at a known distance from an unknown energy release, or to predict expected damage from a known energy release at some distance, based on altitude and distance.
This paper discusses the formation of the reinforced shock wave and formation of the Mach front/stem effect. Although a bolide does not have a fire ball in the same sense as a nuclear weapon detonation does it does emit a substantial portion of its energy as thermal radiation which at lower altitudes would cause serious thermal burns and the associated precursor effects mentioned in the following paper due to thermal heating of the air near the ground prior to the arrival of the shock front.
http://www.dtic.mil/dtic/tr/fulltext/u2/a159214.pdf
Bottom line is that air blast phenomenon from bolide explosions on break up are well within the range of air blast that have the potential to do extreme damage to large metropolitan areas. The would not normally be the “smoking hole crater” depicted in the movies because most objects break up at altitude, but could cause significant air blast and thermal pulse damage over a city wide area. It is only a matter of time that such an event occurs, and emergency planners should consider how to respond to that possibility.
@Larry Cullen Ledwick –
All relevant stuff. As far as they go.
Four things they leave out.
1. On a more vertical path, the air resistance and temperature rise happens more quickly, giving an entirely different and more steep temperature and pressure and turbulence curve – and a more sudden self-destruction curve. (In addition, all incoming bodies are not equal. Some are more fragile than others, some are more cohesive. This strongly affects the results.) I am surprised they did not address this and explain how it affects the height of the “explosion”. Which will happen? A lower “explosion”? A higher one? The same? I don’t know. That is their job.
The body melts only a little at a time, on the front (leading) surface – not the entire body melting all together at the same time. The process of ablation is only happening in the front-most surface and only for a few millimeters at a time. “Fusion crusts” (google “fusion crust meteorwrongs”) on meteors only measure 1 or 2 millimeters – not much at all. When melted (ablated) droplets are pushed off the front surface by the air turbulence, they are quickly evaporated by the temperatures, evaporation very much accelerated by the velocity of the air blowing around the meteor (like a convection oven), which makes the process more efficient. The glow of a meteor is due to the evaporation of the molten droplets. We see only the outermost glow, of the front and sides (as the evaporated material flows around the outside and is quickly left behind). ALL of that glow is rocky/metallic material in gaseous state. That is material that is no longer part of the meteor. All of that material has expanded as it changes from solid to liquid, and then again to gas. The apparent size of the meteor is much greater than the solid meteor at any given moment.
2. Contrary to most people’s beliefs, the meteor does not “explode” from something inside it, like an atom bomb or a conventional bomb. What appear to be explosions are moments when faults/cracks within the object cause pieces to break off. This suddenly exposed material makes for a suddenly larger amount of material being ablated into vapors. This happens when the internal strength of the meteor meets forces beyond its capacity to remain integral. That breakup spot is normally going to be at the front edge, because that is where the forces are greatest. The air, as you know, is massively compressed and heated by the velocity of the meteor pushing into the air ahead of it – and the inability of that air to get out of the way fast enough. It also induces massive forces upon the face of the object and massive turbulence.
When such a breakup causes more surface area is exposed it means that we see what looks like an explosion. But there is no fuel inside to explode. ALL of the vaporizatino is on the front surface – NOT on the inside. If one defines “explosion” as rapid expansion – which is one of the scientific meanings of the term – it is all an explosion, but not in terms that people usually think of it. It is not from the inside out, but from the front side being melted and then vaporized. The entire ablation process is explosion, if viewed from the perspective of rapid expansion. (The infrasound article mentions this, that Chelyabinsk was a spread-out event, that they could read its passage through the atmosphere, because of this continuous “explosion”/expansion going on.) The flaring (three or four of them at Chelyabinsk) is the same process, only more so – when those chunks break off and more leading surface is exposed to the super-heated air.
The final flare-up was apparently when the biggest fault within the meteor was encountered: The object did a final and large disintegration. The object found in Lake Chebarkul broke apart from the rest of it, or vice versa – when the internal faulting caused many smaller pieces to break off simultaneously, leaving mostly only the lake meteorite (454 kg) to continue the main path down to the lake. The rest was strewn around along the path – those didn’t ablate completely.
3. As most people will realize when they think about it, most meteors/bolides that have been seen and/or videoed come in at shallow angles. Watch any video – the bolides are going across the sky with many looking like they are paralleling the ground. We are left with a question: Is this the norm, or is this some artifact of our times, of video cameras? Or a variable in time because maybe in some periods lower is more common?
Most people also think that meteors come straight out of space and all are aimed directly at Earth. Even those who study them seem to always give 45° as the average angle of entry. I do not have the wherewithal to research this, but IMHO this is a wrong assumption. I don’t know where they get it, except maybe from simply assuming that there are 90 possible degrees and they assume that all those angles are equally represented. But there is nothing in the history of meteors that indicates that in the real meteor world high angle impacts are equally represented. All that are depicted in paintings of old show objects careening across the sky almost horizontally. In modern times this seems to be the case, too.
Instead, I submit that low angle entries are by far the most common. Why would this be so? Because the Earth has a gravity well. This is the spherical region around the Earth that anything passing through will encounter sufficient gravity and be captured by the Earth. The faster the object, the smaller the gravity well, because they can whiz to the far side of the well before their path becomes a death spiral. The gravity well is associated with the escape velocity of Earth, and is similar in some ways to a Schwartzchild radius of a black hole.
Since the gravity well is many times larger than the Earth, the “catcher’s mitt” of the Earth is much larger than the body itself. For NEOs, the target, then is not only the Earth, but it’s gravity well. When an object is caught within it, the object begins a death spiral, down to the Earth. This gives a lower angle to the object, relative to the surface. The object will “wrap around” the planet. It’s path will be a function of both its speed and how close to the center it was aimed when it first encountered the gravity well. Just as science fiction stories and NASA space probes talk about using a planet to “slingshot” around and gain speed, the meteors try to slingshot but don’t make it. That slingshot path is a very unforgiving path; a little miscalculation is disaster. That is what happens to most meteoroids (before entering the atmosphere). Their path wraps around Earth. This must, then, lower their angle of incidence with the atmosphere.
Chelyabinsk was at about 20°. Carancas, a meteor seen to fall in Peru, a few years ago, had a calculated angle of about 67° – more than the 45°, yes. And it made it to the ground. SOME will be greater than the 45°. How many? I haven’t the maths to determine this. Perhaps someone else will do it. It is a function of the diameter of the Earth relative to the diameter of the gravity well. And then it is a function of how out from the center the entry into the gravity well is.
The lower the angle of entry, the longer the object is in the atmosphere, and that means a long time to ablate (melt away) and become smaller. And the higher in the atmosphere the flaring (disintegration) will occur.
All of that is good news, actually. Why? It means that if we intercept an NEO on its way toward Earth, that if we can blast it into smaller objects the size of Chelyabinsk or smaller, we will have one hell of a fireworks display (and perhaps a lot of windows blown out). The oft-pictured idea of blowing one big object apart only to end up with many city-killers may not be true, after all. There CERTAINLY is a size below which we could endure millions of such objects. What is that size? No one has asked yet, that I know of. I am asking now.
Some of such fragments would be blown into more wrap-around orbits, inducing even lower entry angles. Some, though, would end up aimed more toward the Earth’s center of gravity, meaning higher angles of entry. That is where the doing the math on the steepness factor comes in – what is THAT largest size (given the specific relative velocity of the main body)? If we can determine that size, then our mitgation plans will have a greater chance of success.
In any event, the greatest defense we have against city-killers is the atmosphere itself. How it defends us needs to be known to the highest level possible, so tht we can work to help it do its job.
All those “multi-kiloton” “explosions” are our proof that we are HIGHLY protected, though not 100%. It DOES behoove us to learn how to make up the balance. I suggest doing it so that the atmosphere can do the rest.
4. I also submit that comparisons to nuclear blast tests should be done with some caution. Why? Because a nuclear explosion has a unique internal source of energy and a unique velocity of expansion, based in the quickness of its explosion. The “fuel” for meteors is quite different, and is, if anything, the “explosion” occurs over a much longer time span – even at the moment of the flare-up. In addition, it is still only the front edge doing the ablation/expansion, NOT the entire body. This, in itself, points to a flaw in any equating of volume to the forces that are later reverse calculated. The flare-up is an increase in the frontal area, and THAT is almost all that is being experienced on the ground.
Without addressing the differences in the actual mechanisms, comparisons to nuclear blasts are imprecise, at best. The expansion forces going out at different velocities, for example, means that the curves will be different as measured at different distances. I’d certainly think the nuclear has a different curve. If so, then the reverse engineering of it will come up with a wrong ground zero force.
Fortunately NASA is developing a manned transportation system that will reach into deep space if one is detected that would require human hands to deploy hardware to the surface of an approaching object. Otherwise there is nothing else on the drawing boards that could do the job, every other human based system is LEO only.
RACookPE1978 says:
“persistently claim that mythological wands like an ion engine (that does not exist)”
So what is that thing that Dawn uses to change orbit? A mythological wand perhaps?
Garcia says:
“Since the gravity well is many times larger than the Earth, the “catcher’s mitt” of the Earth is much larger than the body itself. For NEOs, the target, then is not only the Earth, but it’s gravity well. When an object is caught within it, the object begins a death spiral, down to the Earth”
Sorry but no. No object can ever arrive at Earth with a velocity lower than 11 km/s, so it won’t “spiral in”. It will come in in a fairly stright trajectory and the angle of impact depends on how far from “dead center” it hits.
Steve, yes some of your observations are correct, there are differences between a true explosion as in a weapon detonation and the pressure front created by a super sonic object.
When an object is moving at some 60 times the speed of sound it acts like a large piston and compresses the air in front of it to very high pressures creating a bow shock wave (sonic boom). As you mention, the moment the object undergoes breakup you suddenly have a massive increase in frontal area and the rate of energy transfer to the atmosphere goes off the charts, as the effective size of that piston becomes very large in a matter of a few seconds.
That said, once the shock wave moves well away from the object it is simply just another powerful shock wave in air and behaves the same as the blast wave from a true chemical or nuclear explosion. The high pressure front does not know or care how it was created once it slows down to the prevailing speed of sound of the atmosphere at its location.
When that shock front reaches the ground it will interact with the surface and buildings exactly as the shock front from any air burst of similar power and over pressure.
They are not identical, but the nuclear weapon testing behavior is the best real world analog for such events which we have high quality data.
The Earth has been built out of rocks ‘falling’ from space – a natural process known as accretion. This process has never actually stopped, it has simply slowed over time as the amount of rocky debris hurtling around in the Solar System has been progressively depleted. In its early stages the process was probably too intense for complex life to survive at all, but for the last billion or so years it really hasn’t caused much of a problem to complex life, apart from the occasional really big one every 100m years or so that has knocked life back to simpler forms that have had to start the whole tedious process of evolution all over again. It seems likely to me that the current extremely advanced level of evolution here on Earth is at least partly a result of the diminished frequency and severity of such catastrophic impacts, and that whilst they are still not out of the question, we probably have relatively little to worry about.
But then, I am an optimist..
thingadonta says:
April 19, 2014 at 6:23 pm
Their claim that the threat from asteriods is ’3-10 times higher than previously predicted’ is a data hockeystick. Sounds like a sales pitch to me.
thingadona,
No. This is data from a reliable system, designed to detect air detonations at nuclear weapon multi kiloton levels. The data hasn’t been ‘proxied’ or ‘adjusted’ or screwed with in any way that I know of.. Hard data is just that. Sometimes hard to acquire. Never refuted by idle speculation or ‘drive by’ analyses. If you’re in the Seattle area, why thingadonta you drop by the Flight Museum this Tuesday eve and listen to their presentation.
Mac
Larry –
Points taken. Yes, I do agree that the nuclear info we have is the best we’ve got. So far – and maybe for a long time. That first portion, before it gets slowed to sonic, is the portion I was talking about. How much of a difference does it make? Hell if I know. But those first few thousand milliseconds there IS a lot of difference that should carry over – for example maybe a lot bigger pre-sonic shock wave front radius.
I appreciate your feedback on the other points. When I learned about ablation, I was blown way by what was really going on. Interesting stuff.
I AM convinced that the threat is smaller than I thought a year ago. Chelyabinsk taught me some things. For the size of the object I was REALLY surprised at the small extent of the damage. It gave me the impression that it could have been twice as big and had only minimal deaths, if any.
I really DO think that if we could come up with a mitigation plan to pulverize to a high level that we can reduce the damage/risk immensely. We don’t have to save every life – or even every city. The big threat is not city-killer but extinction event. That Younger Dryas impact hypothesis was a big one. Also Shoemaker-Levy 9’s 20 or so fragments airbursting in Jupiter’s atmosphere in 1994 showed how huge some events can be. The largest one was about 1.3 km, with 2 or 3 more close behind, and the plumes were as large as Earth and more. Somewhere in that range of SL-9 and Chelyabinsk there is a threshold that we need to determine reliably and then plan around it. My guess now is in the middle of the range. A year ago I thought it was around 200 meters. That would be a city-killer. But that is also TEN times bigger than Chelyabinsk.
Are those out there? Yes. Will we spot them all by the time we need to do something? I am sure we will. And then we need to continue as well as decide what mitigation is really going to do a decent job. As far as I’ve seen, we really don’t have a good enough plane yet. NASA’s puny budget doesn’t help. Dave Morrison has nothing to work with. But spending so much on Mars is NOT helping.
Jim Butts says:
April 20, 2014 at 12:21 am
…….. Given the large velocity requirement but low acceleration requirement (starting from low earth orbit) this would appear to be a good application of nuclear powered rockets. And, it is interesting to consider how the nuclear rocket power supply could be incorporated into the nuclear device payload. This mission will require not just Rocket Scientists but Nuclear Rocket Scientists!
Jim,
Right on target! In the process of this development activity, we create the nuclear powered rockets we must have, if we hope to have humans on Mars or in the asteroid belt within the next 30 years. We need rockets that can accelerate continuously to the trip midpoint and then decelerate continuously to the objective, if we are to have reasonable travel times (~ 6 to 7 months) for the trip to Mars orbit. Note that the continuous accelerations will help the ‘MarGoNauts’, because it reduces the documented muscle and bone loss experienced by astronauts in unaccelerated space flight of months long durations…. and gets them there years before they would arrive by conventional chemical rockets that rely on traditional but inefficient ‘burn and coast’ approach.
Let’s focus our AGW misled friends false concerns to a small but real, verifiable threat to humans and all species on the planet Earth. Many of our friends already have the ‘dinosaur killing asteroid impact’ meme embedded in their psyches. Let’s redirect the AGW bloated budget fantasia to a small but very real threat to humanity…. and spend that damn misspent AGW money on a nuclear rocket development program that serves multiple purposes!
It’s time for mankind to take those first toddling steps away from the home crib….. and raiding the AGW funds to do it would be Ohhhhhhh, Soooooooo Satisfying!
Mac
Well, if we increase our CO2 shield they’ll all burn up, right?
peter says:
April 20, 2014 at 6:51 am
…..On the other hand. I support the idea of instigating a large scale program to build the resources needed to detect and possibly deflect such perils. The reason is that the spin-off befits would be enormous. We are talking actual engineering, which almost has to result in real-world applications.
peter,
++10! This is the point! This is why we must focus the general population’s attention on small but real threats to the planet. The Shoemaker-Levy planetary bombardment on Jupiter July 1994 illustrates this well. Much more on that topic here: http://www2.jpl.nasa.gov/sl9/
The development of nuclear rockets alone would yield many spinoff applications, not the least is the energy dense and long life nuclear rockets we must have for manned exploration of our solar system in the next 50 years.
Mac
I don’t know and correct me if I am wrong, but would a nuclear or many nuclear rockets be enough to deflect a huge asteroid from hitting earth, or deflect it towards the moon? If it broke up into many pieces wouldn’t that bring contamination into our atmosphere? This is the larger pieces that broke off hit the earth anyway? I suppose we will never know?
bushbunny –
As little as they’ve been able to work on this problem (NASA is always very low on $$$), I assure you that all those questions have been asked by those studying the possibility. Quite a number of possible deflection scenarios have been looked into, including nukes, hitting a body head on, solar sails, all kinds of stuff – some less feasible than others. And they also have asked what about the radiation.
As to larger fragments still hitting the Earth, that is a major concern, so you are asking the right questions.
Personally, I’ve written to them suggesting a nuke option in which they simultaneously nuke it on both sides and on top, too, to pulverize it all as much as possible. Smaller fragments are much less dangerous. What constitutes small enough? That would be the $64,000 question.
The big problems are four-fold: If we get insufficient warning is one. One other is if we get NO warning. The third is if it is just too damned big. The fourth is if it comes before we are prepared. All of those apply only to ones that we NEED to stop – big ones. As time goes on, we will learn more and more and be able to address the questions better and better. Right now we are only in kindergarten – almost no experience with that world and pretty green behind the ears. But not TOTALLY. And we have good tools and minds to put on them.
The global warming scare has been robbing a lot of scientific fields of money for about 25 years now. This impact thing isn’t the only scientific problem going begging for money. This one is so much more potentially devastating, even if we don’t understand our risk just yet. Or lack of risk. Certainly with objects hitting the planet every several months we keep getting reminded. Russia very much sat up and took notice in February of last year. Others, too.
As these people point out, our calculation of the frequency of these objects has been going DOWN. From Gerritt Verschuur, “Impact!: The Threat of Comets and Asteroids,” in 1996,
From that book, Hills and Goda are quoted,
That was what we knew as of 1996. Those numbers are pretty close to what I thought one year ago. We are about 1/3 of the way along that timetable. We should know 1/3 or more of them by now. And we do. Progress is being made. SOME articles like this one are useful in keeping SOME funding going. (Damn that global warming, anyway!)
We are looking. We are planning a mitigation scenario, and we are realizing more and more what the real risk is. We aren’t there yet, and with a reasonable amount of funding and effort we will continue to size up the realities. The odds are very much in our favor that we are beginning soon enough and will have a workable plan long before we need one.