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.

Comments

APOP-Whut?

[Crypto Gnome]

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.

FUD alert..

[fadeaway]

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..

Re:FUD alert..

[daeg]

"Apophis-sized" implying that the plans would be equally valid for similarly sized bodies even with Apophis missing us in a few decades.

Re:what if they miss hteir shot

[LWATCDR]

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.

Re:oh noez!

[maz2331]

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.

Re:Uh oh...

[onemorechip]

Or, you can use the Doomsday Algorithm.

Re:oh noez!

[rbanffy]

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.

Re:clean nukes are just old propaganda

[Muhammar]

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)

Re:S.T.U.P.I.D.

[vertinox]

The Japanese were determined to fight on to get a better peace deal. They had already lost the war so of course they were suing for peace. The only question remains, is it right to target military installations in the cities of your enemy during a time of war to force his surrender, knowing that tens of thousands of civilians will die.

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_Hi roshima_and_Nagasaki#Opposition

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.