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Nukes Against Earth-Impacting Asteroids
TopSpin writes "Flight International reports that scientists at the Marshall Space Flight Center have developed designs for an array of asteroid interceptors wielding 1.2-megaton B83 nuclear warheads. The hypothetical mission for these designs is based on an Apophis-sized Earth impactor 2 to 5 years out. According to NASA, 'Nuclear standoff explosions are assessed to be 10-100 times more effective [at deflection] than the non-nuclear alternatives analyzed in this study." On April 13, 2029, Apophis will pass closer to earth than geosynchronous satellites orbit.
In case you were wondering, Apophis is the Greek form of the name for the Egyptian Demon Apep.
Otherwise known as the personification of all that is evil.
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I think I'd be pretty hard for them to miss so badly that they somehow manage to hit the earth, since they'd be trying to hit it in space.
Apophis was lowered to 0 on the Torino scale sometime last fall. I'm not sure why it even warranted a mention in this particular context..
exploding nuclear weapons from a distance only works if the asteroid is fairly solid, like the metallic [M-type] asteroids. The more porous asteroids [there seem to be many] don't seem to respond as well to such explosions. As for the Armageddon-type way of dealing with asteroids, you just made a single asteroid into a hail of dangerous shrapnel. Although if we exploded a nuclear charge [a smaller one] that only tosses up a part of the asteroid and direct the shrapnel away from Eath, the shrapnel would go in one direction [wherever your plan dictates] and the asteroid generally goes in the opposing direction, knocking it off course. over a period of several years even a small orbital change will result in Earth being safe for now. [hopefully we have that much time if not start sipping your favorite alcoholic beverage :) ]
Sigs are too short to say anything truly profound so read the above post instead.
April 13, 2029 is indeed a Friday. Look it up yourselves if you don't believe me. Luckily, we'll all be dead in December 2012, so this asteroid's simply to finish off the rest of the life on the planet.
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I have to wonder if you where just kidding or are don't know anything about nuclear weapons.
From the 40s up through I think the 70s many nuclear weapons where detonated in the atmosphere. While it was a really bad plan life pretty much kept on living. A miss would probably not hit the earth and a launch accident wouldn't cause a nuclear detonation. A common method of safeing a nuclear weapon involves filling the pit with a neutron absorbing wire. Once the weapon leaves the atmosphere a motor will pull the wire out of the core and only then the weapon will be capable of nuclear detonation. Not only that most modern weapons are much cleaner then the bombs of the 50s.
So I wouldn't to see them launching them daily I think risk to benefit ratio is pretty good.
See my blog http://ilovecookes.blogspot.com/ for light hearted technical information.
It would go off but would look nothing like an atmospheric burst. It would be a really bright spherical event that mostly produced an incredibly intense flux of gamma rays, with some neutrons as well. The only actual matter to heat up would be the bomb itself, so the size of the visible explosion would be small, but unbelivably bright. The idea is to cause this really intense light and gamma ray burst to heat the surface of the asteroid enough to cause vaporization and ablation. That would cause a small thrust that changes the direction of the asteroid enough to miss the Earth.
Engineers say a bee can't flap its wings and fly; and it cannot. A bee (and for that matter, flies) remain airborne because their wings trace an s-like path through the air, allowing them to move through the air in much the same way as a shark.
Think of it like a ceiling fan that goes back and forth. If it didn't have the ability to turn back on itself, it wouldn't do much to the air. However, if the blades bent in different directions for each direction, it would be able to produce a downdraft.
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Or, you can use the Doomsday Algorithm.
But, I wanted socialized health insurance!
The main enemy in Stargate SG-1 was Apophis.
It would be completely different.
The first destructive effect is caused by the radiated energy itself, but most of the destructive power of an atmospheric nuclear detonation comes from the quick heating and displacement of huge quantities of air that creates the explosive shock-wave.
In space, only the radiated energy of the detonation remains. While it would be sufficient to deflect an asteroid, a nuke is nowhere near as destructive in deep space than it is on Earth.
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The radiation from the nuke isn't the problem with that. The main effects are (a) EMP and interfering with electrical equipment, and (b) fucking up the magnetosphere, and possibly reducing the Earth's shielding from cosmic radiation. Neither of which are good, but better to risk those effects than the certainty of a large asteroid hit.
-b.
It is not true at all that "most modern weapons are much cleaner than the bombes of the 50s. In fact the fusion yield of modern weapons accounts for less than 40% of the total yield, most of the yield actually comes from fission of the uranium container that doubles as a reflector. "clean weapons" can be produced by using non-fissionable reflector like lead, this causes at leat 40% increase in total weight of the weapon design while reducing the total yield approximately to one half. The example of a super-clean bomb is Tsar Bomba that exploded at about 52MT, a lead-reflected test of a 100MT design.
For military the intense radiation from fission of the uranium reflector is an "added bonus". The premium in thermonuclear warhead design is on light weight and narrow diameter (long narrow-cone re-entry vehicles have much better precision than fat ones) in compromise with low cost (low consumption of expensive materials like tritium and plutonium) and high reliability.
The clean weapon was a temporary fad in 50s and early 60s, it was used by rival weapon design team to justify existence of Lawrence Livermore Laboratory and was oversold, being seized upon by politicians it got disproportionate coverage in print - but it never resulted in a weaponised design. The reality is that even a "clean" bomb designs are still an order of magnitude dirtier than Hiroshima and don't offer any military advantage so they are not stockpiled. The peaceful uses of clean nukes like digging harbors and re-livening natural gas and oil fields never materialized as it turned out that produced crater (or gas) was unpleasantly radioactive (because of neutron-induced radiation, with long-lived radioisotopes like C-14 and tritium)
I doubt that we will ever figure out - and I suspect that even if we did figure out we couldn't do much about it
Did you read the full study? It quantifies the "gravity tractor" along with the other methods mentioned, the gravity tractor being the most useless, other than conventional explosives. If you don't like nuclear, a simple high-velocity kinetic impactor is the next most effective (as long as it's a single solid object).
Momentum change [in log10(kg m/s)], given a 9,000kg vehicle launch mass:
Nuclear, Subsurface: 11.9
Nuclear, Surface: 11.5
Nuclear, Standoff - Neutron: 10.3
Nuclear, Standoff - X-ray: 9.9
Kinetic @50km/s (avg): 9.0
Kinetic @10km/s (avg): 8.5
Surface Thruster (non-rotating asteroid) @10 years: 8.1
Surface Thruster (rotating asteroid) @10 years: 7.7
Gravity Tractor, @10 years: 6.9
Conventional Explosive, Subsurface: 6.8
Conventional Explosive, Surface: 6.4
Momentum change [in log10(kg m/s)] required to deflect the following:
Hypothetical long-period 1km comet with 9-24 months to impact: 12.8
Hypothetical 1km asteroid 15yr ahead: 10.5
VD17, a 500m asteroid for 2088: 9.6
Apophis after 2029 approach, assuming a 2036 a collision prediction: 9.4
Hypothetical 200m asteroid 10 yr ahead: 8.7
Apophis by 2029 (with current orbit knowledge): 8.5
Apophis by 2029 (with highly accurate orbit knowledge): 6.3
The point of the distinction between the last two is that the probability window we have to push out of the earth's path becomes much smaller the more accurately we know the orbital parameters of the object. So the more accurately we can calculate it, the less we have to actually push it (up to a point, of course). Also, it looks like very little is gained by exploding things underground as opposed to on the surface. So we apparently aren't going to need a crack team of good-looking drilling experts after all.
Read the manual FFS.. Aim away from your face! :)
The impact of a cubic kilometer of matter (with density = 1000 kg/m3) traveling at 11 km/s is 6e+19 J. The explosion and the debris falling all over the planet would heat up the atmosphere significantly. Calculating from http://www.oco.noaa.gov/index.jsp?show_page=page_r oc.jsp&nav=universal, the atmospheric heat capacity is about 3e+18 J/K. so if the bulk of the energy is absorbed by the atmosphere, there will be about a 20-kelvin average short-term temperature increase around the globe. If the asteroid is slightly larger or denser, oven-like average temperatures are possible
I dunno... Lets ask what the Allied High Commanders and Staff thought:
General Dwight D. Eisenhower "In 1945 Secretary of War Stimson, visiting my headquarters in Germany, informed me that our government was preparing to drop an atomic bomb on Japan. I was one of those who felt that there were a number of cogent reasons to question the wisdom of such an act. During his recitation of the relevant facts, I had been conscious of a feeling of depression and so I voiced to him my grave misgivings, first on the basis of my belief that Japan was already defeated and that dropping the bomb was completely unnecessary, and secondly because I thought that our country should avoid shocking world opinion by the use of a weapon whose employment was, I thought, no longer mandatory as a measure to save American lives." Fleet Admiral Chester W. Nimitz, Commander in Chief of the U.S. Pacific Fleet "The Japanese had, in fact, already sued for peace. The atomic bomb played no decisive part, from a purely military point of view, in the defeat of Japan." Admiral William D. Leahy, Chief of Staff to President Truman "The use of [the atomic bombs] at Hiroshima and Nagasaki was of no material assistance in our war against Japan. The Japanese were already defeated and ready to surrender." Report from the post war United States Strategic Bombing Survey "Based on a detailed investigation of all the facts, and supported by the testimony of the surviving Japanese leaders involved, it is the Survey's opinion that certainly prior to 31 December 1945, and in all probability prior to 1 November 1945, Japan would have surrendered even if the atomic bombs had not been dropped, even if Russia had not entered the war, and even if no invasion had been planned or contemplated." And my favorite from the guy who actually encouraged Einstein to write FDR, Leo Szilard "Let me say only this much to the moral issue involved: Suppose Germany had developed two bombs before we had any bombs. And suppose Germany had dropped one bomb, say, on Rochester and the other on Buffalo, and then having run out of bombs she would have lost the war. Can anyone doubt that we would then have defined the dropping of atomic bombs on cities as a war crime, and that we would have sentenced the Germans who were guilty of this crime to death at Nuremberg and hanged them?" Source: http://en.wikipedia.org/wiki/Atomic_bombings_of_H
So yeah... According to some of the major members of the US military and those who took part in the Manhattan project, the bombs were unneeded.
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While your opinion with regards to humiliation is admirable, your knowledge of this specific history is nonexistent. After being given unconditional surrender, we went into Japan and helped them in every way possible. We spent billions of dollars helping them rebuild, created a newer and more efficient infrastructure and shared most of our technology with them. We did not humiliate them--we treated them like equals. To quote wikipedia, "MacArthur and his GHQ staff helped a devastated Japan rebuild itself, institute a democratic government, and chart a course that made Japan one of the world's leading industrial powers." http://en.wikipedia.org/wiki/Occupied_Japan/
MacArthur supervised the occupation of Japan, and made sure that the Japanese food network was the first thing reconstructed; he even forbid the US forces from eating any of the scarce Japanese food. Democracy flourished, and MacArthur and emperor Hirohito became friends.
Please do not accuse the United States of attempting to humiliate Japan, because there is simply no credibility to that statement.
The total casualty estimates if we had invaded Japan, based on the island hopping campaign so far in the war, were over 1 million allied and as many as 10 million total Japanese. We were planning on using gas, including captured Nazi nerve gas to cut down on allied casualties.
Even if we had not invaded Japan, any potential non-nuclear outcome would have been MUCH worse.
Japan depended heavily on inland water craft for transport. We had decimated this system and were in the process of finishing it off. Their railway system was very vulnerable to air attack and we were working on that two.
Almost all agriculture in Japan at the time was FAR from most of the population. If we had simply continued to bombard Japan from the air, the Japanese people would have starved to death. The estimates run as high as 60% of the population in less than a year (1944 and 1945 were bad rice years to begin with). The Japanese leadership did not care. This did not take into account the fact that ALL allied prisoners would have died, along with possibly millions in China and other parts of Asia.
Also, the USSR would have invaded more of the northern islands if the war had not ended when it did. If you think Berlin was a mess, think how bad THAT would have been.