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”.
Steve Garcia says:
April 21, 2014 at 12:41 pm
……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.
Steve,
Close but …. consider this. Approximately 95% of all meteorite remnants examined were iron-nickel bearing meteors. The metal is present in elemental form, not as metal oxides. As such, the iron and nickel are readily oxidized as temps rise above the melting point, an exothermic reaction. At the front face of a meteor entering earths atmosphere, frictional heating from the atmosphere icreases as the meteor drives deeper into it. As the front face of the meteor melts, the iron-nickel metal exothermically oxidizes, adding to the frictional heating. The deeper into the atmosphere the meteor drives the more oxygen is available for exothermic oxidation… and the more that oxygen is compressed at the front face of the melting metal meteor.
Have you ever seen an oxygen-acetylene ‘cutting torch’ in operation on common steels, alloys of mostly iron? A ‘neutral’ oxy-acetylene flame is used to heat the metal to the melting point. As soon as the steel glows ‘white hot’ incandescent, an extra stream of pure oxygen is added to the heating flame initiating a rapid oxidation, high heat yield exothermic reaction. The added exothermic heat combined with the pressurized feed of oxygen rich gas into the melting iron creates the conditions that allow rapid thermal cutting of thick steel plate. Multiply this mundane industrial process by the pressures at the face of a iron-nickel meteor entering Earths oxygen rich atmosphere at 16 to 28 kilometers per second. Think “biggest friggin’ cutting torch you can imagine” and multiply by 1000………
It isn’t just ablation, melting, and vaporization ‘going on’……. and this can lead to unpredictable break ups in metal rich meteors that greatly enhance the expansion of the meteor effective diameter and the corresponding pressure/shock wave.
Mac
Mac the Knife –
You seem to have the iron meteor percentages backward. Only 4.4% are iron, 94.6% are stony, and 1% are stony-iron. http://en.wikipedia.org/wiki/Meteorite_fall_statistics
As a mechanical design engineer in industry I worked for years in plants with oxy-acetylene cutting departments. The pressurized secondary oxygen is also providing the velocity to drive out the slag, if I recall. In one plant we had ones that would make vertical cuts in 15″ mild steel.
That process is fairly close to the ablation process, actually – first melt and then blow out the droplets with high pressure.
bushbunny says:
April 21, 2014 at 9:51 pm
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,
Not so much a correction as a clarification of how the systems work together to achieve a deflection of a potentially earth impacting meteor or comet.
There are three parts to a detection, intercept, and deflection system. The first part is the search system, based on conventional radars, infrared based systems, and optical systems. The further out we can detect an earth intercepting object and predict its trajectory, the more time we have to respond effectively.
The second part of the system is the rocket that delivers the deflection system/payload to the orbital intercept with the incoming object. The further out the object is intercepted, the smaller the impulse the deflection system must apply to the object to nudge it out of an earth intercepting orbit. Orbit here usually means a highly elliptical orbit of the incoming boloid around the sun that happens to intercept the earth in it’s orbital path around the sun. The more powerful and faster the rocket delivery system is, the farther out we can intercept the incoming boloid and the smaller the deflection payload can be. Current technology chemical rockets are relatively low energy, ‘burn for a short time, coast slowly most of the way to the object, then a short deceleration burn to match orbits’ slow delivery systems. Nuclear fission powered mass reactions rockets provide much higher kinetic energies and can provide continuous acceleration to the midpoint of the orbital intercept with the incoming object and then continuous deceleration to match orbits with the object before deploying the deflection system. It’s a potentially much faster delivery system, giving us the capability to intercept the object with a modest deflection payload further away from earth… or get a big deflection payload to an object that we detected when it was already closer in than we might like .
The third part of the system is the deflection system. If the incoming object can be intercepted sufficiently far away from the earth, a smaller ‘push’ is needed to deflect it from an earth intercepting orbit. The closer in it gets before we can get a deflection payload to it, the bigger the ‘push’ we need to apply to move it enough to miss earth.
Then there is the physical make up of the incoming object itself. If it is a stoney chondrite asteroid or a high metal content asteroid, we probably can use a suitably sized nuclear fission payload/warhead on the rocket to apply the ‘push’. If it is a ‘soft’ comet, made of a mix of ice and rock (the ‘hot fudge sunday of Lucifers Hammer, Niven and Pournelle), we will have to use a softer ‘push’ deflection payload to ‘push it’ without breaking it up…. or just bomb the hell out of it and accept the infall of the smaller but less lethal pieces.
Does this help understanding of how then detection, rocket delivery system, and deflection payload systems must work together, bushbunny? This is the kind of astrophysics, astronautics, nuclear power, macro-engineering, and pyrotechnics that I really enjoy. There are few natural hazards that the creativity of engaged and driven humans cannot overcome, given the unfettered opportunity to experiment, create, and eventually succeed. This is a small but very real threat to humankind and all life on this precious little blue and white marble, third rock from the sun, called Earth. The solution is achievable and worth doing.
Mac
Steve Garcia says:
April 21, 2014 at 10:48 pm
Mac the Knife –
You seem to have the iron meteor percentages backward. Only 4.4% are iron, 94.6% are stony, and 1% are stony-iron.
Steve,
See http://meteorites.wustl.edu/id/metal.htm for source of my info.
As for my bona fides, I’m a two-time metallurgical engineering degree offender from UW-Madison WI, with specializations in welding and aerospace alloys, and +27 years experience in all kinds of aerospace, astronautics, missiles, and nuclear power engineering/materials applications. I was a welder and mechanic (among other things) before I ever started college, and can still handle a cutting torch, TIG welder, or oxy-acetylene welding torch today. Suffice it to say ‘Simple melting is one thing, Exothermic cutting is much more aggressive and accelerated.’
I tipped Anthony to this topic because I very much want to shift the public awareness from the unsupported fear of AGW to real and measurable threats to the planet Earth and all its denizens. Asteroid or cometary impact is one of those small but quantifiably real threats to our ancestral Ark. Addressing it will drive essential innovations to all aspects of space exploration systems.
Sure, there are others (vulcanism, earth quakes, tsunamis, etc) that should all have greater concern and attention than AGW also… but I chose this topic, as I really believe that man’s destiny lies out in the stepping stones of the planets of our solar system….. and then on to the stars. If we can divert funding from AGW to these applications, it is money well spent.
Mac
PS: I appreciate your lengthy and well informed comments on this thread and Larry Ledwick’s as well!
Thanks guys, I agree, but I read an article that NASA was planning towing asteroids to orbit the moon to study them?? I hope they know their physics? Wouldn’t our gravitational pull bring them closer to us? Nice one NASA!
who do i have to help make rich to make this go away?
Steve Garcia said: April 21, 2014 at 12:41 pm
“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.”
Thank you for your enlightening comments, Steve, but regretfully I must disagree on the above para. Agreed the ‘catcher’s mitt’ is much greater than the Earth. But, unless the thing is sufficiently close to the Earth to be slowed – by atmosphere or something else – it will keep going – behaving exactly as a comet does when it passes the Sun. It will have a parabolic or hyperbolic orbit wrt the Earth, or, depending on what may have happened earlier in its wanderings, be in an elliptical orbit with the Earth at one focus. Of course, if the elliptical orbit takes long enough, the Earth will have moved on and the shape of the ellipse will be mangled – how much I would not try to guess. But if the object comes in sufficiently close to the Earth, it will be slowed by the atmosphere, and most likely will, as shown by these recent arrivals, be heated so much it breaks up. With a flatter orbit at higher altitude, it could leave the atmosphere, but return to re-enter the atmosphere , perhaps several times – the favourite return mechanism for space craft before the development of the ablation cone protecting the front end. In this case the object will certainly be on a death spiral.
Shoemaker Levy must presumably have already had one contact with Jupiter, which caused the original very large object to break into many smaller ones, these continuing on the same very tight ellipse which brought them back to Jupiter. If two objects have orbits that cross each other in all three dimensions, then unless the periods are exact multiples and the objects are separated when each crosses the other’s orbit, they will eventually collide. Conversely, if the orbits do not coincide in all three dimensions, they cannot hit each other as long as the orbits do not change – which will happen if there is a near miss.
While it is plausible that the overwhelming majority of things arrive in low orbits – as Steve suggests – consider that these are the ones that last long enough in the high atmosphere to be seen and recorded. How high is the atmosphere? Say, for example, that the atmosphere extends 100 miles. – the height of low orbit satellites. In a vertical arrival, at the speed of a minimum of 11 km/s or 7 miles/s, a vertically falling meteorite will take 14 seconds to enter and hit the Earth. Plenty of shock wave, but arriving so quick it is not likely to be seen. Well, far less likely than the near horizontal Chelyabinsk meteorite to be seen.
I am told that if you see a meteorite land and pick it up you are likely to have your hands burnt – not due to its being hot as much as due to its being intensely cold. Though I would suggest that if it had been following the earth for some time, hence at roughly the same distance from the Sun, it would have attained approximately the same temperature as the Earth’s surface would have if not for the atmosphere and the Earth’s internal heat, ie, just a bit below freezing point of water. Who knows?
OMG! A link to a WUWT blog post from Yahoo! Will wonders never cease…
Mac the Knife –
Very interesting. Yes, I am well aware of that group of wustl web pages, which I refer to as the Meteorwrongs pages. In fact, I was just emailing with Randy Korotev (who authors it) in the last week, about some possible finds in India by a friend of a friend. Small world! (I am NOT a meteorite hunter, though.)
Yes, that page says, “About 95% of all meteorites contain iron-nickel (FeNi) metal.” If you follow the first link on that page (stony chondrites), though, THAT page says this, “Most (>95%) stony meteorites are ordinary chondrites.” Contradictory? Apparently, though this statement seems to only be talking about stony meteorites.
This seems to be harder to find out than it would seem to be. Phrasings on some sites are not clear or they don’t mention percentages.
For example, the National History Museum’s meteor page says, “The majority of meteorite falls are stony meteorites consisting mainly of silicate minerals.” http://www.nhm.ac.uk/nature-online/space/meteorites-dust/meteorite-types/
Okay, then, let’s go back to the wustl pages, since that is where we started out. http://meteorites.wustl.edu/meteorite_types.htm Scroll down the page to the image labeled “ALL METEORS.” The pie charts are a bit confusing, but the text below says this:
“Most meteorites that fall on Earth are stony meteorites. Only a few percent are irons. However, in populated places like North America, people find a greater fraction of the irons because irons tend to be bigger* and are more likely to catch peoples’ attention.
*Although only 2.6% of meteorites are irons, 85% of the mass of all meteorites is in the irons. 11% of the mass is in the stony meteorites.”
That image shows pie chart that clearly states that 97.0% of “all Meteorites” are “stony.”
Does that settle it? Actually, NO, because just below he then goes on to say,
“Most stony meteorites are chondrites, and most chondrites are ordinary chondrites. Chondrites contain iron-nickel metal, which is what makes them attracted to a magnet.”
His “Ordinary Chondrite” page discusses much about the metal in ordinary chondrites.
Since the difference between 95% stony or 95% iron is huge, whenever any site says “most meteorites” I assume they are referring to THAT 95%, not the other. (If that made no sense, ignore it.)
So it still seems unclear to me, because they seem to phrase things in ways that it is unclear whether they are talking on one hand about predominantly metal meterorites, or on the other hand meteorites that include some metal.
So, where are we on this? Frankly, I am not sure. Maybe this: 95% of all meteorites are ordinary chondrites, which contain some percentage of iron.
For myself, 7 years of my career I worked in R&D, doing experiments for scientists and frequently interacting with the metallurgists in our R&D center. I respect you guys. Big time.
What! Me worry.
“Steve Garcia says:
April 21, 2014 at 10:38 pm
…. Quite a number of possible deflection scenarios have been looked into….
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….
And if we get one of those relatively garden-variety Carrington events, or something just a bit bigger, every one of the above four issues will come to bear fatally, plus a fifth – if we are NO LONGER PREPARED, or even ABLE TO PREPARE.
So wouldn’t it make infinitely more sense to deal with the Solar EMP issue before tackling the deflection issue? Or is Solar EMP not considered a credible cause of global infrastructure collapse in this forum?
There have been several in depth discussions regarding Nuclear EMP and solar flare/CME events like the Carrington event. It could also be substantially mitigated at a small fraction of the cost of chasing a phantom issue like global warming.
What happened to reliable computer models showing that no large fragment of a Chelyabinsk-sized meteorite could reach the ground? It should have evaporated high up.
@otropogo – Interesting addition to the discussion. Yes, we should put some priority on that. In the short term it’s probably a bigger risk than an impact, which might not come for a few thousand years – maybe longer.
Without infrastructure, we have no civilization. I am serious about that. Take it away and see how fast people starve and how MANY, right quick. EMP only targets electronics, true, but without electronics, how far back in time do we go, and how fast an we adjust and rebuild? Only as far as the 1950s?
Without at least a PLAN, it could get ugly, real quick.
And Larry Ledwick is right about the cost being so much less than they are talking about with global warming. In fact, in some ways the global warming thing is roughly equal to a slo-mo Carrington event – taking us back in time, costing gazillions of jobs, and starving a right lot of folks.
@Dudley Horscroft 8:32 am:
“Thank you for your enlightening comments, Steve, but regretfully I must disagree on the above para. Agreed the ‘catcher’s mitt’ is much greater than the Earth. But, unless the thing is sufficiently close to the Earth to be slowed – by atmosphere or something else – it will keep going – behaving exactly as a comet does when it passes the Sun.”
Incorrect, Dudley. If the atmosphere slows it, it is captured already – mostly because of the AMOUNT it slows it. And what is the “something else” that might slow it? As it approaches Earth the Earth’s gravity is actually accelerating it.
“It will have a parabolic or hyperbolic orbit wrt the Earth, or, depending on what may have happened earlier in its wanderings, be in an elliptical orbit with the Earth at one focus.”
True, but not if it enters the atmosphere.
“Of course, if the elliptical orbit takes long enough, the Earth will have moved on and the shape of the ellipse will be mangled – how much I would not try to guess.”
There are programs to figure all this out. You don’t have to guess.
“But if the object comes in sufficiently close to the Earth, it will be slowed by the atmosphere, and most likely will, as shown by these recent arrivals, be heated so much it breaks up. With a flatter orbit at higher altitude, it could leave the atmosphere, but return to re-enter the atmosphere , perhaps several times…”
None of this is true. Though it may sound reasonable, no.
“Shoemaker Levy must presumably have already had one contact with Jupiter, which caused the original very large object to break into many smaller ones, these continuing on the same very tight ellipse which brought them back to Jupiter.”
If you have read even a little bit about SL-9, you know that that is exactly what happened. On its last previous close pass of Jupiter it DID break up, and the change in orbit due to that really close pass DID put it on a collision course the very next orbit.
“If two objects have orbits that cross each other in all three dimensions, then unless the periods are exact multiples and the objects are separated when each crosses the other’s orbit, they will eventually collide.”
This is all mitigated by the fact that most planets and asteroids and comets are are in slightly different planes, or inclination. The higher the inclination, the more what you just said is true, that they won’t likely hit. At the same time, even reasonbly close passes can throw the smaller body into god knows what orbit and inclination. Because of this effect on the smaller body, really long term orbits are not necessarily possible to predict.
“Conversely, if the orbits do not coincide in all three dimensions, they cannot hit each other as long as the orbits do not change – which will happen if there is a near miss.”
Your last point is what I just wrote. AS to the first one, not true at all, though it is HIGHLY unlikely. The real point is whether the points at which the smaller object crosses the orbital plane of the larger. If those are farther in or out from the larger body’s orbit – THEN it is impossible. And that is the case for most comets. For NEOs, which are affected by Earth’s gravity to some extent at all times, and which have different orbital times, there is a dance going on – specifically because the orbits DO change.
“While it is plausible that the overwhelming majority of things arrive in low orbits – as Steve suggests – consider that these are the ones that last long enough in the high atmosphere to be seen and recorded.”
I DO put that out there only as what sounds reasonable to me. I don’t know for sure. It is not necessary that they be in high orbits in order to be seen or recorded. Tunguska airbursted at fairly low altitude. People DID see it, though it is not recorded how low it would have been seen when they did.
“How high is the atmosphere? Say, for example, that the atmosphere extends 100 miles. – the height of low orbit satellites. In a vertical arrival, at the speed of a minimum of 11 km/s or 7 miles/s, a vertically falling meteorite will take 14 seconds to enter and hit the Earth. Plenty of shock wave, but arriving so quick it is not likely to be seen. Well, far less likely than the near horizontal Chelyabinsk meteorite to be seen.”
For most of this, I recommend that you simply google the topics and learn a little bit on your own. As to Chelyabinsk, the downward angle, last I heard, was 20°. It DID appear to a lot of people at CosmicTusk.com that it HAD been horizontal – and then had skipped out into space. But we got fooled. Myself, it was only when I saw video from MANY angles and ALL of them appeared to be downward that my instinctual brain accepted that it was a downward path. From the perspective of any particular video it was simply not easy to ascertain a downward angle – since the views were at skewed angles to begin with. At about that same time, someone had managed to look at one of the Chealyabinsk city videos and the shadows and determine pretty correctly about the angle. (In addition, as long as the body was in the atmosphere, technically it was a meteor. Only after it hit the surface did it become a meteorite. BEFORE it entered the atmosphere it was a meteoroid.)
“I am told that if you see a meteorite land and pick it up you are likely to have your hands burnt – not due to its being hot as much as due to its being intensely cold.”
Not even CLOSE to being true. The body was heated a HUGE amount by the air ahead of it, which it was compressing at a really high rate. Touch your refrigerator’s compressor sometime while it is compressing – but be bloody careful!
In addition, I point you to gogogle the Carancas meteorite and read up on people who went to it after seeing it land.
“Though I would suggest that if it had been following the earth for some time, hence at roughly the same distance from the Sun, it would have attained approximately the same temperature as the Earth’s surface would have if not for the atmosphere and the Earth’s internal heat, ie, just a bit below freezing point of water. Who knows?”
In short, no. It is not the Earth’s internal heat that keeps the surface at about 15°C. It is the atmosphere and its greenhouse effect. Without that greenhouse effect, the temp would be -18°C. (If that is wrong, someone here correct me.) The greenhouse effect, then, is GOOD. Without it we would not be living on the surface (and probably not anywhere). -18°C is too damned cold for me!
The net gain in technology setting up the infrustructure to protect ourselves from asteroids would have a positive effect on the economy just like the Apollo program did. Even if another meteor doesn’t hit us for another 10,000 years it is still worth it. Why do we need a impending threat to do the right things anyways?
Re your latest, Steve. Perhaps we are once again “separated by a common language”.
You said:
“Incorrect, Dudley. If the atmosphere slows it, it is captured already – mostly because of the AMOUNT it slows it. And what is the “something else” that might slow it? As it approaches Earth the Earth’s gravity is actually accelerating it.”
Regrets I disagree again. It is only captured if the orbit is changed from hyperbolic or parabolic or an ellipse not focused on the Earth to an ellipse focused on the Earth. It can enter the atmosphere, and have its orbit changed, but still not be captured if it then departs – as far as the Earth is concerned, on another parabolic orbit. Re the “something else”? Here we enter the realm, after the “known knowns”, the “known unknowns” to reach the “unknown unknowns”. That is, what may possibly be there which could cause it to slow but which we have no idea of. Rather like Lord Kelvin, calculating that the Sun could not possibly have lasted more than 500M years, left himself a let out at the end.
“It seems, therefore, on the whole most probable that the sun has not illuminated the earth for 100,000,000 years, and almost certain that he has not done so for 500,000,000 years. As for the future, we may say, with equal certainty, that inhabitants of the earth can not continue to enjoy the light and heat essential to their life for many million years longer unless sources now unknown to us are prepared in the great storehouse of creation.”
(See: http://zapatopi.net/kelvin/papers/on_the_age_of_the_suns_heat.html)
I wrote: “With a flatter orbit at higher altitude, it could leave the atmosphere, but return to re-enter the atmosphere , perhaps several times…” You added: “None of this is true. Though it may sound reasonable, no.”
As to skip re-entry for an object, this has been done for spacecraft. While unlikely, it is feasible that an object at exactly the right angle, could have actually skipped once, even possibly more times. See: http://en.wikipedia.org/wiki/Skip_reentry
I said: “I am told that if you see a meteorite land and pick it up you are likely to have your hands burnt – not due to its being hot as much as due to its being intensely cold.” That is what I said, reporting statements on the temperature of meteorites. In general a small body will have the outer layer heated to melt and be ablated as you say, but then the body will fall comparatively slowly through the lower atmosphere, and the outer skin will be cooled. For a 1 kg rock, say, the terminal velocity might be around 100 to 200 m/s – the lower value being a bit more than the maximum value for a peregrine falcon in a dive. After having most of the speed reduced while the outer skin was being removed, from a height of, say, 20 km the 1 kg remnant would be falling at the terminal velocity, reducing as air resistance increased. This would take, say, 100 seconds from 20 km at 200 m/s, at first through quite cold air. Pretty easy to lose the excess heat from the outer skin.
Thanks for the reference to the Carancas meteorite – I noted the following sentence: “Most larger meteorites are cold in their bulk mass when they land on Earth, since their heated outer layers ablate from the objects before impacting.” This one was hot – or rather the result was. As a back of the envelope estimate, based on the estimated diameter of greater than 3 m, I would say the mass was about 35 tonnes. The KE liberated would render the area rather warm, to say the least.
Finally I would say that -18C is, for most people, “just a bit below freezing point of water”.
Best regards, Steve. I welcome your contributions. If only the CAGW mob would be so willing to discuss matters amicably.
Dudley –
Yes, I much prefer respectful exchanges. We are all on the same side, anyway! I’ve begun a few comment conversations here and elsewhere on different sides of a point and then ended up finding much common ground and new friends.
On this, you seem to be under the impression that objects can relatively easily enter the atmosphere and then “skip” into outer space and not be captured by Earth’s gravity. Remember that even when human space vehicles want to do a skipping maneuver, first, they have to VERY carefully chose the proper velocity AND the proper shallow angle or else they risk not bouncing off at all and entering ballistic orbit – meaning that they fall toward the ground pretty quickly and directly. This is what happens to meteors that become meteorites (some – most – don’t make it all the way down). To skip means to have a too shallow entry angle, and the chances of this by an object is very small – it has to enter a very narrow annulus at close to a tangent.
You say: “As to skip re-entry for an object, this has been done for spacecraft.”
Actually, no, this has never actually been DONE, even though they have long ago determined HOW to do it. (I had to look this up to be sure.) See http://www.aerospaceweb.org/question/spacecraft/q0218.shtml for some nice explanations.
You seem to also misunderstand how MUCH the atmosphere decelerates an object. The “fire” of an object entering the atmosphere is FROM that deceleration – due to the air resistence and the air itself being compressed ahead of the object, which then is what melts the droplets that then vaporize, giving the glow we see. That heating and melting and vaporizing is the kinetic energy being transformed into heat energy. If the velocity drops below 11.2 k/sec at any point in its atmosphereic contact, it’s captured within the atmosphere.
It can also be captured by Earth’s gravity without encountering the atmosphere. To be captured is a larger subset of possibilities than just atmospheric capture (which means a death spiral/ballistic trajectory). These non-atmosphere jobbies seem to be the scenarios you are talking about. Yes? Just like SL-9 was captured by Jupiter’s gravity upon the previous close pass, when the gravity also broke it into fragments. But then those fragments still went FAR from Jupiter before returning. But they WERE captured. Even if their subsequent orbits had not been death spirals. To “be captured” by a planet means that the planet becomes the focal point of the elliptical orbit instead of the Sun. It is my understanding that that is how moons became moons, without being gobbled up by their parent planets.
(More later – I am sleepy!)
“Steve Garcia says:
April 22, 2014 at 8:01 pm
… EMP only targets electronics, true, but without electronics, how far back in time do we go, and how fast an we adjust and rebuild? Only as far as the 1950s?
Without at least a PLAN, it could get ugly, real quick.”
I’m afraid your estimation of the regression effect is a world class understatement. My fear is that the survivors would be so traumatized and brutalized by the event and its aftermath that a complete return to tribal jungle behaviour would characterize humanity – where unknown men are killed on sight, and women and children at best are enslaved. Return to the technology of the 1950s would be a pipe dream, in my opinion. If humanity managed to survive at all in a much more hostile world without the technology to navigate the toxins, it could take a thousand years or more to get back to some level of ordered civilization.
I don’t pretend to know whether the cost of preparing for such an event would be less costly than trying to mitigate climate change or interplanetary impacts. But I do know that we’ll never come to grips with it without first having the will to realistically imagine the social impact of losing electricity for even a few months, let alone a few years, at our current level of dependency. Ideas of reverting to horsepower and buggies, home gardens and wood stoves, are sheer lunacy in the face of this threat, yet they seem to prevail among those who are willing to consider the possibility at all. The sheer number of dead, combined with the density of population and interdependency for food, fuel, and medicines, would make life a desperate struggle for survival for years to come. And whatever leaders this environment throws up are unlikely to be patrons of reason or scientific thought.
If you are interested in the larger picture of what is currently unfolding the read Adam to Apophis: Asteroids, Millenarianism and Climate Change by Nicholas Costa which was published a year ago