For the cost of the difference between business class and economy on most international flights you could outright purchase 2 27" monitors when you go there.
IF you could get them. Finding such equipment in a strange town in a country you don't know and in a language you don't speak more than a few words of, can take a significant chunk of your time.
I've been impressed enough to give job references ("I worked supervising Mr.X at Y for Z months, and when I had to give Mr.X shit for his equipment falling apart, he impressed me with his repairs, and his honesty." He went on to work for much higher pay with less unreliable equipment and so had to lie less.)
And I'm glad to see that others are as imaginative, and effective. Good one, guys and girls! Sock it to them and make sure that the rich thieves pay their taxes!
The FBI issued 192,499 of the demands from 2003 to 2006, and 97 percent of NSLs include a mandatory gag order.
The main reason that Stalin isn't proud and supportive today is that Beria choked him with a pillow. Allegedly. But I gather that the gag order rammed into Stalin's mouth may also have a lot to do with his inability to comment.
How on EARTH did the USA end up with such an incredibly cumbersome system? OR worse : such a set of interlinked, mutually incompatible and incoherent systems? There was a deranged genius? Someone thought it would be a good idea to ask people 74 questions on one day, then hope for an answer, rather than ask them several times over successive days?
I don't have a horse in this race ; but one horse clearly needs a bullet in the head, while the other needs to be flogged into the crowd, to beat down opposition. Who gets the bullet, and who gets the short whip (with a VERY angry wasp glued to the tip!?)?
initially saw a massive success (40+ members showed up at the first meeting). Unfortunately, participation has decreased a lot since then, down to four active members.
That sounds like a fairly normal attrition rate. Pretty much all clubs go through this when they start up. (Sports clubs and other retard-entertainment may be different. But I doubt they'd be much different.)
I feel that the main reason for this decline was the inability to maintain the students' interest at the beginning of the year,
Plus a significant proportion of your membership will have graduated / moved on to other interests / discovered 1-person sex / discovered multi-person sex / moved away... from year to year. You have three interlinked problems : retention of existing members ; recruitment of new members ; co-option of new members into administration of the club. (I'll ignore the dressing of the club with the trappings of democracy. The only time this is going to be a real issue, is when you don't have a membership crisis. Until then, Benign Dictatorship with the window-dressing of a compliant troika is more effective.
as well as general disorganization, which we hope to change next semester.
See above.
Welcome to the wonderful world of politics. You might be under the delusion that you are running a computer club, but in reality you have become a competitor against every member of the club who thinks that they can manage the club better than you. I.e. you're a politician under fire. Enjoy!
Meantime : pack the board (however : read the local election rule book, then put a surf board and 80-piece orchestra on your shoulders before sailing through the larger holes) with your supporters ; run the club the way that you want ; choose your successor (someone who will leave at least one, better two, years later than you) and whip your sock-puppets into line to guarantee a succession. Then grow. Grow! GROW! When you've got enough people who joined in first-year, were active through all of second year, and WILL attend third year... then you can think about transitioning to something that resembles "democracy". But while you're starting and building a club - is not the time to be worrying about other people's opinions.
Someone else is certain to take control of your club at some point. Unless you're particularly sad. So concentrate on GROWTH (dominance if there are relevant competitors), SUCCESSION, and.... well maybe then you can go onto policy. Which your replacement will change, once you're at college (or dead and buried ; same difference).
The manual you need was written by one Niccolo Machiavelli in about 1480. The titles of the roles may have changed slightly ; the actions haven't.
There's a damned good reason that Machiavelli's "human group programming" instruction manual is still in print : it works.
Aren't all of India's enemies on the same continent? Why does it need an intercontinental-range missile?
You might find it instructive to write a list of the countries whose enmity to India you are sure of, and then write a list of their allies. Likewise, write a list of countries whose friendship for India you're sure of, and a list of their enemies.
What proportion of the globe do your 4 lists cover? Enough to require ICBMs?
(I'm not saying that India are right or wrong ; I'm just putting on their shoes and walking a mile in them to try the fit. YMMV. But I doubt you'd come to a significantly different answer.
Apple seams to do fairly well with OS X, and that's not at all like Windows.
Apart from using a paradigm of a desktop with overlapping bits of paper (folders, projects, tasks in hand ; whatever) where you pick up tools from the desktop.... yeah ; nothing like dissimilar.
I returned a previously-dead X86-box to the world of the working computing machine yesterday, by the not-magic of Freegle (you may know it as "Freecycle" ; I don't care about trivial branding issues) and the new owner asserted that he was visually impaired, so graphics performance was not an issue.
This reminded me that the surface "floaters" are not now, and never have been, the important parts of any OS. Different people do have different needs. Stephen Hawkins needs a better stereo microphone at about the same time that Evelyn Glennie needs a new set of loudspeakers and David Blunkett needs to replace his 7x3 pixel monitor with a much bigger 7x3 monitor.
My recently-deceased buddy, Charlie, spent years trying to persuade me that I really needed a VooDoo or better graphics card. Eventually he loaned me his own, and then was somewhat upset when I continued playing games in glorious EGA-equivalent graphics. I still have no real interest in advanced graphics, but it's hard to get a system which doesn't waste ridiculous amounts of copper, silicon and attention on drawing pretty pictures.
The horses (or their riders) do really determine the courses that are going to be taken.
Wow, the betting shills at the side of the Roman Colloseum will be shocked, SHOCKED I tell you!! that this could happen. They thought that it had been stamped-out by the invasion of the accountants.
Could a massive, nuclear powered electromagnetic field protect the ship's crew while in transit at least? [...] but has it at least been considered/debated?
(1) Neutral particles
Particles interact with electromagnetic fields if they have a net charge. Neutral cosmic rays (including photons - gamma rays) don't. Other shielding (massive) would be needed for this purpose. This is decades-to-centuries-old news.
Charged particles.
If you set up a dipole ("North-South") field around the ship.... this would reduce the energy of most such impinging particles. Along one axis. From other directions, they may be accelerated towards the crew-areas. Which would require more shielding.
Interaction with other EM fields
In many orientations of such a (dipole) field, you'd experience drag, or the spacecraft would, against the magnetic field of the planetary or solar system you're inhabiting. Which is likely to cost energy (I think that I can prove that ; but I will hang my head in seat-of-the-pants-estimation shame if you can prove me wrong.
It's an attractive idea. But even the Good Doctor seems to have had to struggle to convince people of the idea. And as "Dr Asimov" (he was a research biochemist in his day job ; something to do with thiotimolene), he still failed to convince himself or his readers.
The most effective, moveable (if slowly) radiation shield consists of some tonnes of mass. Unsurprisingly, the necessary mass is about equivalent to the mass of the atmosphere above almost all slashdotters on any day of the week : 10m of water-equivalent. You might be able to trim it a little (paraffin wax with it's abundance of hydrogen nucleii might have a larger interaction cross-section than (say) 10m of solid steel. Since 8m thickness of paraffin wax would weigh considerably less than 10m of steel, it's worthwhile trying to optimise this.
On the other hand, once you've got your bare structure, you can add volume to your protected at a cylindrical rate (1/r^2, rather than a cubic rate, 1/r^3). And then you ride it, and hope that your cells (and your putative descendant's cells) survive.
Go back and read your classic "hard SF" ; the concept of "banking" your sex cells has been independently invented, and used. Not just in the game world of SF, but as "IVF" and lots of related techniques.
The carefully (and expensively) educated nurses and doctors have spent centuries not applying it.
OK ; until 1.8 (approx) centuries ago, nobody had actually tried looking at data and carrying out interventions to examine the hypothesis that "washing hands between visiting different patients reduces rates of disease transmission between patients." Semmelweis did it ; since then, nobody in the health care industry has had an excuse, except "ignorance".
That is not an acceptable excuse these-centuries.
I'll be fair to the medical professionals : lots of other groups to whom it should apply have also failed to apply it. I had a safety alert come round my Work email a couple of days ago about someone who had rubbed his eye while wearing gloves contaminated with [something not-nice], and got considerable pain and lots of inflammation as his pay-back.
I've made (essentially) the same mistake myself in the past ; mea culpa. It's not just "quacks" that fuck up.
I'm bored with constructive (-ish) criticism, and I'll just carp : this is a new idea?
Just last week I was listening to an audiobook by Robert Heinlein (you know - the only serious contender that Dr Asimov had for the title "the Master" in the world of science fiction ; him) where Andrew "Slipstick" Libby is introduced into the cast list... by double-checking the results of calculations for precisely this sort of asteroid-moving explosion. They created the initial crater by physically setting a charge on the asteroid surface, then deepened it with one (or more) nukes in the crater. Same story ; same problems. But Heinlein had the excuse of not having a lot of data to work with about the internal strength and coherence of real asteroids. We're slowing our rate of finding surprises now - because we've gone from seeing examples towards having statistically worthwhile samples of data.
"Revolt in 2100" was how the audiobook was titled ; the short-story was something different though. "Misfit"?
I still prefer the odds on the broken up asteroid than the guaranteed end of human life full asteroid.
I still prefer the odds of having hundreds (or more) of humans in places other than the bottom of a gravity well, so that when the surface has stopped burning and the rest of the debris has settled into a ring (that itself would make space flight planners wish they lived in the clean skies of the 2020s), the re-population of the planet might start.
Indeed it may be prudent to have a second warhead to explode after the first one to give the pieces more momentum away from the line of impact (we'd need around 100m/s, that's a lot of momentum to be giving to potentially massive lumps of rocky iron).
In a "shit or burst" scenario, that would be a "nice to have" fallback plan ; whether you'd have enough time between detonation and point of "no point for the second drive bomb"... would be very situation specific.
Why do you think that Joe Random Impactor would be "rocky iron" ; they make up only a few percent of observed falls (even if I do have a sample of one on my mantelshelf ; "pretty" does not equal "representative"), while the large, large majority of objects in space are inhomogeneous, brittle, fragile lumps of poorly consolidated lumps of rubble with the cohesive strength of a firm beach sand. Your mental image for planning is inappropriate to the most likely problem.
You are aware that our planet is continuously peppered by space debris, amounting to something like 10000 to 1000000 tonnes per year? [tulane.edu]
Perfectly well aware of it, thank you.
1,000,000 tonnes, assuming 1.8 tonnes/m^3 is about 51m radius. Around three times the size of the Chelyabinsk impactor and so around 27 times it's effects.
A 1km impactor would be around 520,000,000 tonnes. Oh, sorry, that's for ice ; 942,477,796.1 or so tonnes for 1.8SG "rock".
Slipping a factor of 2 or 3 is banker-level innumeracy. A factor of 500+ suggests that you work in politics?
1) Smaller chunks would have a slightly different trajectory so that some would miss us entirely while others
And the further away you did this, the longer they would have to spread from their origin point. So in the limit, you come back to doing anything you can do, as early as possible. It's probably also best to point the weapon in the correct direction too.
2) Exploding 1 incredibly large roid in the the lower atmosphere would have the effect you are describing, but by breaking it up, the mass of the particles entering the lower atmosphere would be drastically smaller. Thus, creating less "dust cloud".
50% (-ish) of our atmosphere is below 8km above sea level. There are dozens of known and measured asteroids and comets bigger than that. The "interesting" impactors would be touching down on the surface before the back side was even into the thick atmosphere, and the leading edge would have taken on the order of a quarter second to travel through the atmosphere.
OK ; I'll allow for an entry at an angle from the vertical. Give the impactor a half a second to pass through the atmosphere.
Let's say you have a 10km diameter impactor, and you hit it with the nukes when it is 1000km out (5 times the height of the ISS). Do the geometry : anything that is deflected by less than 40degrees from the original flightpath is going to impact on the Earth. (Actually, I make it 40.8 degrees ; not a significant difference.)
Now go back to your video of the Space Shuttle 'Columbia' disintegration in the upper atmosphere. What was the cone angle of the debris? 20 degrees? 10 degrees? Not a lot.
Space defence systems must operate a long way from the Earth. Otherwise, it's far too late. And too little ; but mostly "too late".
Does surface area to volume ratio not come into play?
Yes, it does : the volume of the atmosphere is finite, as is it's mass and heat capacity. Same for the oceans. If you efficiently distribute a large amount of energy (the kinetic energy of an incoming impactor) through the hemisphere of impact, then you will heat up that half of the atmosphere to the point of (say) burning paper at a colloquial 451degF. Which will not be good.
Of course, if you inefficiently distribute the energy (say, by having the impactor hit at one small point), then the local temperatures will be much higher, causing an explosion of the vaporised rock at the impact centre. This will throw red-to-white-to-blue-hot material up into the atmosphere (well, actually, no atmosphere would be left, locally ; that doesn't change matters significantly) with 99% of the material on ballistic trajectories that will bring the hot material back down to the Earth's surface over the next few days in a fairly random distribution. So, average temperatures of the atmosphere (for the same impact) would only increase to around 451/2=225.5degF, which would roast flesh, not make it burst into flame.
Asteroid impacts are bad news. It is probably not coincidence that the earliest traces of life that we can detect on this planet were probably able to tolerate living in scalding-hot water. Previous life-forms that couldn't survive in scalding water, died.
Any object small enough to be destroyed this way would be best avoided by evacuating the locale where it is going to hit.
Very few objects are "small enough to be destroyed" ; most are large enough that the application of energy (i.e., setting off a bomb) will fragment them, producing what is known as shrapnel.
Take a couple of hundred grammes of explosive and detonate it in free air. It might pop your eardrums if you're in the same room as it, but you're unlikely to even get a bruise from bits of the wrapper hitting you. Now put the same mass of explosive in the middle of a paper bag filled with nails from the hardware store... and you've built your first nail bomb, beloved of terrorists everywhere.
The proposal in this article is very specifically about avoiding that fragmentation effect, while applying maximum lateral thrust to the object to move it from a threatening orbit into a less-threatening orbit. But it's going to be a very fine balance between maximising the lateral thrust (particularly important if you don't have much time to act with) and minimising the risk of generating a cloud of shrapnel heading towards Earth. In the mathematical limit, you'd shoot pebbles (bullets) at the rock, so that the rock's orbit was moved. But that would take time to have it's effect.
There is no quick, simple, easy cheap solution. Hopefully we manage to get distributed around multiple independent locations before we need to try this sort of thing, because at best, it is very risky.
I am assuming that extinction level impact asteroid wont be short notice one
Why do you assume that?
Once we've got all the significant rocks in the inner solar system catalogued, so that we know where they're going to be and they are long-notice visitors. Then the remainder of potential short-notice visitors are the ones coming in at random (-ish) orientations from the Oort Cloud. And they're much, much harder to survey for. And they come in fast and hard, with little warning.
As we improve out cataloguing of the inner solar system, the remaining probability of a short-notice impactor moves increasingly towards the long-period and single-apparition comets. And, of course, the possible (though never seen), extra-solar impactor.
If it were really a short notice asteroid... and there were no alternative... then it is, as we say in the caves, "shit or burst time".
The really important thing is to
(1) not be in the short notice asteroid situation
in which case we need to continue improving our detection scopes and projection computing resources. And get every historical astronomical photograph digitised thoroughly so that new discoveries can be post-discovered (identified in 50-year-old plates) if they're there. Or confirmed to not be there. (Both types of data improve estimation of orbits.) Programmes for that are already in work, so the biggest issue is funding.
(2) have a back-up plan in the event that the deflection-by-nuke plan fails.
Which means, having people (hundreds minimum ; thousands better) living off-planet in a locally-sustained way. That's much harder. But it's already on our species' long-term "to-do" list.
Are you really going to base the survival of our species on a single-shot effort?
Ummm, light intensity of a megaton bomb at 3 million miles range...
To back-of-the-envelope calculate that, I could look for light intensity figures. But why? I can use inverse-square. A megaton at 3 million miles range will have a certain intensity; so at half the range, you'd need a quarter of the tonnage to get the same effect. Quick spreadsheet fat-fingering and... when the tonnage gets down to about a kilogramme (remember that the yield is initially in tonnes of TNT equivalent, and it's an energy release ; it doesn't really matter if it's nuclear, chemical, or kinetic energy) you're at a range of... I make it about 91 miles. Thinking of the Mythbuster's explosive orgasms, would that be visible at 91 miles?
Bring the range down to a metre or so... and you're looking at in the order of 1/20th gramme of TNT equivalent. Which is in the ballpark of a drop of water. You'd see it. If it were TNT un-contained on a bench when it detonated at that range, I'd wear safety spectacles. But not sun glasses.
Yeah, I guess it would give a light show in the same sort of intensity range as conventional fireworks. Maybe a bit brighter. One flash.
You really think Bruce Willis will live that long?
Or that they've got enough video in the can already that they can completely replace live-action-Bruce with computer-generated-Bruce, and nobody will be able to tell the difference?
Plausible to you. None of my geologist colleagues who have thought about it rate the theory.
that the shock waves from the Chixulub impact merged together 180 degrees around the planet and caused the Deccan Traps. 10,000 years of volcanoes, anyone?
More like half- to three-quarters of a million years. And the rate would be on the order of a Pinatubo every few years to a Laki every century or so. Most of the dinosaurs probably never knew that anything was hitting them. Until Chixulub, and then they had 200,000 to 300,000 years to think about it before dying out. Say, a couple of hundred generations. The length of time since humans invented/ discovered agriculture, in terms of human generations.
Most people don't "get" geological time. Which is fine by me : keeps me in employment.
A lot of little masses are better then one huge one.
The energy is dissipated over a wider area, and it has more surface area exposed, so more of the mass will 'burn up' in the atmosphere.
Please feel free to carry out the experiments necessary to validate your theory, but using a planet that doesn't have all the known life in the universe on it.
I wouldn't particularly object to you doing it using the Moon. But you'd need to put an atmosphere on it first. Enjoy fixing that.
Ha ha, but serious. Let's practice steering asteroids, and blowing them up, using Venus as a target. Then we'll have two potentially capable technologies for our protection, and some real experimental evidence on which one is harder or faster to do, and which one is the more destructive in the event of incomplete success.
Slashdot Mirror
IF you could get them. Finding such equipment in a strange town in a country you don't know and in a language you don't speak more than a few words of, can take a significant chunk of your time.
I've been impressed enough to give job references ("I worked supervising Mr.X at Y for Z months, and when I had to give Mr.X shit for his equipment falling apart, he impressed me with his repairs, and his honesty." He went on to work for much higher pay with less unreliable equipment and so had to lie less.) And I'm glad to see that others are as imaginative, and effective. Good one, guys and girls! Sock it to them and make sure that the rich thieves pay their taxes!
A "Free" and "open" society?
What is that cackling laughter I hear in the difference? Oh, it's the future. E.N.J.O.Y.
The main reason that Stalin isn't proud and supportive today is that Beria choked him with a pillow. Allegedly. But I gather that the gag order rammed into Stalin's mouth may also have a lot to do with his inability to comment.
Nope.
How on EARTH did the USA end up with such an incredibly cumbersome system? OR worse : such a set of interlinked, mutually incompatible and incoherent systems? There was a deranged genius? Someone thought it would be a good idea to ask people 74 questions on one day, then hope for an answer, rather than ask them several times over successive days?
I don't have a horse in this race ; but one horse clearly needs a bullet in the head, while the other needs to be flogged into the crowd, to beat down opposition. Who gets the bullet, and who gets the short whip (with a VERY angry wasp glued to the tip!?)?
That sounds like a fairly normal attrition rate. Pretty much all clubs go through this when they start up. (Sports clubs and other retard-entertainment may be different. But I doubt they'd be much different.)
Plus a significant proportion of your membership will have graduated / moved on to other interests / discovered 1-person sex / discovered multi-person sex / moved away ... from year to year. You have three interlinked problems : retention of existing members ; recruitment of new members ; co-option of new members into administration of the club. (I'll ignore the dressing of the club with the trappings of democracy. The only time this is going to be a real issue, is when you don't have a membership crisis. Until then, Benign Dictatorship with the window-dressing of a compliant troika is more effective.
See above.
Welcome to the wonderful world of politics. You might be under the delusion that you are running a computer club, but in reality you have become a competitor against every member of the club who thinks that they can manage the club better than you. I.e. you're a politician under fire. Enjoy!
Meantime : pack the board (however : read the local election rule book, then put a surf board and 80-piece orchestra on your shoulders before sailing through the larger holes) with your supporters ; run the club the way that you want ; choose your successor (someone who will leave at least one, better two, years later than you) and whip your sock-puppets into line to guarantee a succession. Then grow. Grow! GROW! When you've got enough people who joined in first-year, were active through all of second year, and WILL attend third year ... then you can think about transitioning to something that resembles "democracy". But while you're starting and building a club - is not the time to be worrying about other people's opinions.
Someone else is certain to take control of your club at some point. Unless you're particularly sad. So concentrate on GROWTH (dominance if there are relevant competitors), SUCCESSION, and .... well maybe then you can go onto policy. Which your replacement will change, once you're at college (or dead and buried ; same difference).
The manual you need was written by one Niccolo Machiavelli in about 1480. The titles of the roles may have changed slightly ; the actions haven't.
There's a damned good reason that Machiavelli's "human group programming" instruction manual is still in print : it works.
Cynic?? Moi? Mais oui ; avec raison!
You might find it instructive to write a list of the countries whose enmity to India you are sure of, and then write a list of their allies. Likewise, write a list of countries whose friendship for India you're sure of, and a list of their enemies.
What proportion of the globe do your 4 lists cover? Enough to require ICBMs?
(I'm not saying that India are right or wrong ; I'm just putting on their shoes and walking a mile in them to try the fit. YMMV. But I doubt you'd come to a significantly different answer.
Apart from using a paradigm of a desktop with overlapping bits of paper (folders, projects, tasks in hand ; whatever) where you pick up tools from the desktop .... yeah ; nothing like dissimilar.
I returned a previously-dead X86-box to the world of the working computing machine yesterday, by the not-magic of Freegle (you may know it as "Freecycle" ; I don't care about trivial branding issues) and the new owner asserted that he was visually impaired, so graphics performance was not an issue.
This reminded me that the surface "floaters" are not now, and never have been, the important parts of any OS. Different people do have different needs. Stephen Hawkins needs a better stereo microphone at about the same time that Evelyn Glennie needs a new set of loudspeakers and David Blunkett needs to replace his 7x3 pixel monitor with a much bigger 7x3 monitor.
My recently-deceased buddy, Charlie, spent years trying to persuade me that I really needed a VooDoo or better graphics card. Eventually he loaned me his own, and then was somewhat upset when I continued playing games in glorious EGA-equivalent graphics. I still have no real interest in advanced graphics, but it's hard to get a system which doesn't waste ridiculous amounts of copper, silicon and attention on drawing pretty pictures.
The horses (or their riders) do really determine the courses that are going to be taken.
Wow, the betting shills at the side of the Roman Colloseum will be shocked, SHOCKED I tell you!! that this could happen. They thought that it had been stamped-out by the invasion of the accountants.
It's an attractive idea. But even the Good Doctor seems to have had to struggle to convince people of the idea. And as "Dr Asimov" (he was a research biochemist in his day job ; something to do with thiotimolene), he still failed to convince himself or his readers.
The most effective, moveable (if slowly) radiation shield consists of some tonnes of mass. Unsurprisingly, the necessary mass is about equivalent to the mass of the atmosphere above almost all slashdotters on any day of the week : 10m of water-equivalent. You might be able to trim it a little (paraffin wax with it's abundance of hydrogen nucleii might have a larger interaction cross-section than (say) 10m of solid steel. Since 8m thickness of paraffin wax would weigh considerably less than 10m of steel, it's worthwhile trying to optimise this.
On the other hand, once you've got your bare structure, you can add volume to your protected at a cylindrical rate (1/r^2, rather than a cubic rate, 1/r^3). And then you ride it, and hope that your cells (and your putative descendant's cells) survive.
Go back and read your classic "hard SF" ; the concept of "banking" your sex cells has been independently invented, and used. Not just in the game world of SF, but as "IVF" and lots of related techniques.
The carefully (and expensively) educated nurses and doctors have spent centuries not applying it.
OK ; until 1.8 (approx) centuries ago, nobody had actually tried looking at data and carrying out interventions to examine the hypothesis that "washing hands between visiting different patients reduces rates of disease transmission between patients." Semmelweis did it ; since then, nobody in the health care industry has had an excuse, except "ignorance".
That is not an acceptable excuse these-centuries.
I'll be fair to the medical professionals : lots of other groups to whom it should apply have also failed to apply it. I had a safety alert come round my Work email a couple of days ago about someone who had rubbed his eye while wearing gloves contaminated with [something not-nice], and got considerable pain and lots of inflammation as his pay-back.
I've made (essentially) the same mistake myself in the past ; mea culpa. It's not just "quacks" that fuck up.
Just last week I was listening to an audiobook by Robert Heinlein (you know - the only serious contender that Dr Asimov had for the title "the Master" in the world of science fiction ; him) where Andrew "Slipstick" Libby is introduced into the cast list ... by double-checking the results of calculations for precisely this sort of asteroid-moving explosion. They created the initial crater by physically setting a charge on the asteroid surface, then deepened it with one (or more) nukes in the crater. Same story ; same problems. But Heinlein had the excuse of not having a lot of data to work with about the internal strength and coherence of real asteroids. We're slowing our rate of finding surprises now - because we've gone from seeing examples towards having statistically worthwhile samples of data.
"Revolt in 2100" was how the audiobook was titled ; the short-story was something different though. "Misfit"?
I still prefer the odds of having hundreds (or more) of humans in places other than the bottom of a gravity well, so that when the surface has stopped burning and the rest of the debris has settled into a ring (that itself would make space flight planners wish they lived in the clean skies of the 2020s), the re-population of the planet might start.
In a "shit or burst" scenario, that would be a "nice to have" fallback plan ; whether you'd have enough time between detonation and point of "no point for the second drive bomb" ... would be very situation specific.
Why do you think that Joe Random Impactor would be "rocky iron" ; they make up only a few percent of observed falls (even if I do have a sample of one on my mantelshelf ; "pretty" does not equal "representative"), while the large, large majority of objects in space are inhomogeneous, brittle, fragile lumps of poorly consolidated lumps of rubble with the cohesive strength of a firm beach sand. Your mental image for planning is inappropriate to the most likely problem.
Optimist.
I think that this thread is proving you wrong very adequately.
Sad. Depressing. But true.
Perfectly well aware of it, thank you.
1,000,000 tonnes, assuming 1.8 tonnes/m^3 is about 51m radius. Around three times the size of the Chelyabinsk impactor and so around 27 times it's effects.
A 1km impactor would be around 520,000,000 tonnes. Oh, sorry, that's for ice ; 942,477,796.1 or so tonnes for 1.8SG "rock".
Slipping a factor of 2 or 3 is banker-level innumeracy. A factor of 500+ suggests that you work in politics?
And the further away you did this, the longer they would have to spread from their origin point. So in the limit, you come back to doing anything you can do, as early as possible. It's probably also best to point the weapon in the correct direction too.
50% (-ish) of our atmosphere is below 8km above sea level. There are dozens of known and measured asteroids and comets bigger than that. The "interesting" impactors would be touching down on the surface before the back side was even into the thick atmosphere, and the leading edge would have taken on the order of a quarter second to travel through the atmosphere.
OK ; I'll allow for an entry at an angle from the vertical. Give the impactor a half a second to pass through the atmosphere.
Let's say you have a 10km diameter impactor, and you hit it with the nukes when it is 1000km out (5 times the height of the ISS). Do the geometry : anything that is deflected by less than 40degrees from the original flightpath is going to impact on the Earth. (Actually, I make it 40.8 degrees ; not a significant difference.)
Now go back to your video of the Space Shuttle 'Columbia' disintegration in the upper atmosphere. What was the cone angle of the debris? 20 degrees? 10 degrees? Not a lot.
Space defence systems must operate a long way from the Earth. Otherwise, it's far too late. And too little ; but mostly "too late".
Yes, it does : the volume of the atmosphere is finite, as is it's mass and heat capacity. Same for the oceans. If you efficiently distribute a large amount of energy (the kinetic energy of an incoming impactor) through the hemisphere of impact, then you will heat up that half of the atmosphere to the point of (say) burning paper at a colloquial 451degF. Which will not be good.
Of course, if you inefficiently distribute the energy (say, by having the impactor hit at one small point), then the local temperatures will be much higher, causing an explosion of the vaporised rock at the impact centre. This will throw red-to-white-to-blue-hot material up into the atmosphere (well, actually, no atmosphere would be left, locally ; that doesn't change matters significantly) with 99% of the material on ballistic trajectories that will bring the hot material back down to the Earth's surface over the next few days in a fairly random distribution. So, average temperatures of the atmosphere (for the same impact) would only increase to around 451/2=225.5degF, which would roast flesh, not make it burst into flame.
Asteroid impacts are bad news. It is probably not coincidence that the earliest traces of life that we can detect on this planet were probably able to tolerate living in scalding-hot water. Previous life-forms that couldn't survive in scalding water, died.
Very few objects are "small enough to be destroyed" ; most are large enough that the application of energy (i.e., setting off a bomb) will fragment them, producing what is known as shrapnel.
Take a couple of hundred grammes of explosive and detonate it in free air. It might pop your eardrums if you're in the same room as it, but you're unlikely to even get a bruise from bits of the wrapper hitting you. Now put the same mass of explosive in the middle of a paper bag filled with nails from the hardware store ... and you've built your first nail bomb, beloved of terrorists everywhere.
The proposal in this article is very specifically about avoiding that fragmentation effect, while applying maximum lateral thrust to the object to move it from a threatening orbit into a less-threatening orbit. But it's going to be a very fine balance between maximising the lateral thrust (particularly important if you don't have much time to act with) and minimising the risk of generating a cloud of shrapnel heading towards Earth. In the mathematical limit, you'd shoot pebbles (bullets) at the rock, so that the rock's orbit was moved. But that would take time to have it's effect.
There is no quick, simple, easy cheap solution. Hopefully we manage to get distributed around multiple independent locations before we need to try this sort of thing, because at best, it is very risky.
Why do you assume that?
Once we've got all the significant rocks in the inner solar system catalogued, so that we know where they're going to be and they are long-notice visitors. Then the remainder of potential short-notice visitors are the ones coming in at random (-ish) orientations from the Oort Cloud. And they're much, much harder to survey for. And they come in fast and hard, with little warning.
As we improve out cataloguing of the inner solar system, the remaining probability of a short-notice impactor moves increasingly towards the long-period and single-apparition comets. And, of course, the possible (though never seen), extra-solar impactor.
The really important thing is to
(1) not be in the short notice asteroid situation in which case we need to continue improving our detection scopes and projection computing resources. And get every historical astronomical photograph digitised thoroughly so that new discoveries can be post-discovered (identified in 50-year-old plates) if they're there. Or confirmed to not be there. (Both types of data improve estimation of orbits.) Programmes for that are already in work, so the biggest issue is funding. (2) have a back-up plan in the event that the deflection-by-nuke plan fails. Which means, having people (hundreds minimum ; thousands better) living off-planet in a locally-sustained way. That's much harder. But it's already on our species' long-term "to-do" list.Are you really going to base the survival of our species on a single-shot effort?
Ummm, light intensity of a megaton bomb at 3 million miles range ...
To back-of-the-envelope calculate that, I could look for light intensity figures. But why? I can use inverse-square. A megaton at 3 million miles range will have a certain intensity; so at half the range, you'd need a quarter of the tonnage to get the same effect. Quick spreadsheet fat-fingering and ... when the tonnage gets down to about a kilogramme (remember that the yield is initially in tonnes of TNT equivalent, and it's an energy release ; it doesn't really matter if it's nuclear, chemical, or kinetic energy) you're at a range of ... I make it about 91 miles. Thinking of the Mythbuster's explosive orgasms, would that be visible at 91 miles?
Bring the range down to a metre or so ... and you're looking at in the order of 1/20th gramme of TNT equivalent. Which is in the ballpark of a drop of water. You'd see it. If it were TNT un-contained on a bench when it detonated at that range, I'd wear safety spectacles. But not sun glasses.
Yeah, I guess it would give a light show in the same sort of intensity range as conventional fireworks. Maybe a bit brighter. One flash.
Or that they've got enough video in the can already that they can completely replace live-action-Bruce with computer-generated-Bruce, and nobody will be able to tell the difference?
Or, perhaps they already did?
Plausible to you. None of my geologist colleagues who have thought about it rate the theory.
More like half- to three-quarters of a million years. And the rate would be on the order of a Pinatubo every few years to a Laki every century or so. Most of the dinosaurs probably never knew that anything was hitting them. Until Chixulub, and then they had 200,000 to 300,000 years to think about it before dying out. Say, a couple of hundred generations. The length of time since humans invented/ discovered agriculture, in terms of human generations.
Most people don't "get" geological time. Which is fine by me : keeps me in employment.
Please feel free to carry out the experiments necessary to validate your theory, but using a planet that doesn't have all the known life in the universe on it.
I wouldn't particularly object to you doing it using the Moon. But you'd need to put an atmosphere on it first. Enjoy fixing that.
Ha ha, but serious. Let's practice steering asteroids, and blowing them up, using Venus as a target. Then we'll have two potentially capable technologies for our protection, and some real experimental evidence on which one is harder or faster to do, and which one is the more destructive in the event of incomplete success.
I was wondering if someone else would notice that.