Nukes Against Earth-Impacting Asteroids 491
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.
Re:what if they miss hteir shot (Score:2, Insightful)
Add to that distance the fact that the radiation, well... radiates in all directions, and the very small peice of that radiation that would reach the earth is going to be, in whole, less than that coming out from the diode in your TV remote.
The thing will be so large and so fast, and so far away, even knocking it slightly off course will likely steer it farther away!
Space is really, really, really big, and things move really, really, really fast.
Re:FUD alert.. (Score:3, Insightful)
Ad impact! (Score:2, Insightful)
Re:what if they miss hteir shot (Score:4, Insightful)
rj
Re:Star Wars Fakeout (Score:1, Insightful)
One person being killed by an act of nature is an unfortunate personal tragedy. Everyone being killed by an act of nature is extinction. Having the wealth to escape this kind of treat is the point of all our economic activity from a larger evolutionary perspective.
Re:Star Wars Fakeout (Score:5, Insightful)
That's true. The potential damage from getting hit is very, very large though - and the probability isn't quite small enough to completely discount. Major meteor impacts have occurred with some frequency on a geological time scale - it seems prudent to actually do the risk assessment and take appropriate action if necessary.
As for the foreign energy independence issue, sure that's important. That doesn't mean that astronomers who specialize in asteroids should drop their careers for it any more than you should drop your career (whatever it is) to worry about potential meteor impacts.
Re:Star Wars Fakeout (Score:3, Insightful)
People with actual ability to use statistics know that it's unlikely that anyone will be killed by an asteroid for hundreds of years, if not thousands or even millions.
Re:what if they miss hteir shot (Score:5, Insightful)
worse yet ... (Score:4, Insightful)
Re:Star Wars Fakeout (Score:3, Insightful)
But the money being spent on this research and all active missile defense research absolutely pales in comparison to what we are spending in Iraq. Yes, we should get out of Iraq - out of the "crosshairs of foreign energy supplies" - but that doesn't mean we can't also continue to pursue missile defense technologies, and secure our borders while we're at it.
In my opinion missile defense is precisely the sort of national security policy that should be supported by someone interested in limited government or interested in limiting U.S. imperialism around the world.
If we have a mature, comprehensive air and space defense solution, we don't have to worry about policing the world, and we don't have to have talk about nuclear first strikes against sovereign nations.
Re:Sneaky way to get weapons into space (Score:3, Insightful)
Re:S.T.U.P.I.D. (Score:3, Insightful)
Perhaps it's also the right day -- after all, nuclear bombs in this case are being used to save rather than slaughter.
-b.
Re:this is not armageddon NASA :) (Score:3, Insightful)
Atmospheric heating of the objects, if there are enough of them, can result in a significant increase in the temperature of the atmosphere in general. This is the very, very bad effect of either the "Armageddon" or the endgame in "Deep Impact".
Deflection is the right answer. Probably the only good answer.
Re:this is not armageddon NASA :) (Score:4, Insightful)
Oh thats just such a Russian attitude...
Re:Star Wars Fakeout (Score:5, Insightful)
Huh? Of course the damage it would do doesn't make the event more likely, but it makes the event more serious.
If one event is likely, but has minimal impact if it occurs, it might be worth ignoring, in order to concentrate on a less likely event that has disastrous consequences.
Since a large asteroid impact could be a mass extinction event, something capable of wiping out our entire ecosystem -- not to mention civilization -- even if it's unlikely, it's worth working to prevent. Compared to that, everything except the possibility of nuclear war (or equally disastrous environmental collapse) pales in comparison.
Re:FUD alert.. (Score:3, Insightful)
No, it doesn't become a chaotic system at all.
Orbital mechanics and climate simulations are, no pun intended, worlds apart.
Re:oh noez! (Score:3, Insightful)
Actually, the way the two standoff nuclear explosives they studied would work, is to bombard the asteroid with "highly concentrated and directionally focused x-rays or neutrons," the latter of course being a "neutron bomb." The neutron bomb is the more effective method, presumably because of the momentum transferred directly by the high-speed shower of neutrons.
Re:What about other options? (Score:1, Insightful)
"More effective" in this context means either (or some combination of both) that the method in question is capable of deflecting a larger mass or deflecting the same mass with less lead time.
This is incredibly wrong. The delta-v required to put a sufficiently massive object into the same orbit as any object on an arbitrary earth-intersecting orbit is going to be enormous. You can possibly (for incredibly small values of possible) use gravitational sling-shotting to throw your weight near the NEO, but that's simply delaying the fuel requirement for later when you then need to counteract the momentum gained by sling-shotting to match the velocity of the NEO. "Sir, we can get to the NEO in 3 months if we slingshot around Venus, but we'll be traveling at 30,000km/hr in the wrong direction when we get there".
All told, when the fate of the planet is is at stake, you go with proven, time-tested technology (nukes, heavy extra-orbital launch platforms) rather than hypothetical ones (scopes guaranteed to detect all possible threats decades in advance, as-yet-undesigned ultra-heavy extra-orbital launch platforms). The fact that the former is a viable solution to a wider range of threats (lower lead time, superior deflection capability for the same lead time and lift capability) is just gravy.
Re:What about other options? (Score:5, Insightful)
Would you rather the object remained trackable and predictable, or became unstable and maybe whangs into us a few orbits later?
Re:S.T.U.P.I.D. (Score:1, Insightful)
Re:S.T.U.P.I.D. (Score:5, Insightful)
Japan was not going to surrender in two weeks, they were via diplomatic back channels suing for peace, this is not the same as offering unconditional surrender. In the end the Japanese still insisted that they be allowed to keep their Emporer, and the allies agreed to this demand, instead of being belligerent. I don't know where you got this myth that the Japanese were willing to surrender unconditionally, but the whole point of further increasing the size of their armed services during and after Okinawa was to make taking the islands of Japan as much like the battle for Okinawa as possible. That would have resulted in extreme causalities on both sides. The idea was that by a few tens of thousands of casualties the Americans and their allies would agree to more favourable terms than unconditional surrender. Heck if it had been like Okinawa they might even have managed to force those terms, which would have been a disaster.
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. If you believe the allies were right to demand unconditional surrender (which I do), and if you believe that the Americans should have kept their nerve conducting the invasion and no accepted a lesser peace, then one is forced to ask the following question. Which course of action would cost more civilian lives, more destruction of infrastructure, and more military lives. The answer to all three is invasion. Dropping the bomb saved lives, civilian, military, and preserved what little remained of Japans infrastructure.
It is to my mind, the only time in history dropping the bomb would be acceptable, because of the unique set of circumstances at the time.
Re:S.T.U.P.I.D. (Score:5, Insightful)
I firmly believe that Hitler was helped by the fact that he was able to convince many Germans that the treaty of Versaille was unfair because the 'November Criminals' had signed it while Germany still had some effective military and could still fight the war. Coupled with the fact that the terms of the treaty were humiliating themselves (full blame for the war placed on Germany, reparations, Sudentenland handed over to the new Czechoslovakia, splitting Germany in two). Unconditional surrender is not about humiliation. The requirement of unconditional surrender existed because the conduct of those states with which the allies were fighting required wholesale removal of thier leadership and replacement by an authority that would be cast iron allies of the West. Unconditional surrender was just another way of saying to the militarist leaders of Japan "we will dismantle your government, and you will be tried for war crimes".
Re:S.T.U.P.I.D. (Score:5, Insightful)
I'm certainly not glorifying the killing of civilians. However, if I presented to you a choice. Kill a quarter of a million Japanese now, or kill half a million Americans and 4 million Japanese over three to four months of bloody combat, what would you choose? If you choose to kill four million more people just because you don't like the word nuclear or because you think in some way being shot is better than dieing in giant fireball, then I believe you to be a cold heartless bastard.
Hell the United States is still handing out purple hearts of 1945 manufacture because of the anticipated casualties of the Japanese campaign were higher than the sum total of wounded or dead servicemen in every war since.
I suggested what the Japanese intent was. They believed they could break their 'inferior' American foe. The Americans had plans for Olympic which forecast many more casualties that the Japanese thought the Americans could take. All you have done is prove my point, the Americans would have accepted the high casualties and pushed on, since they planned for them anyway. The bottom line is that while the Japanese hoped to bring the war to an end with tens of thousands of casualties by breaking the American will to fight, that was not going to happen. You are suggesting an option (American capitulation to the Japanese plan) which was never on the table to begin with.
Re:what if they miss hteir shot (Score:3, Insightful)
Do not unsafe the weapon until it clears the magnetosphere. They will be launching the weapons when the target is still years away so there is no need to unsafe the weapon until it is a long way from the earth.
The simplest way to safe the weapon is to fill the core with wire that absorbs neutrons. You just pull the wire out to arm the bomb. as long as the core is filled a high yield event is impossible. No high yield event no EMP.
Plus the launch would be from the Cape. Most of the flight would not be over any large cities. It would be over the Atlantic and equatorial Africa.
No it isn't 100% safe but nothing is. It would beat the heck out of getting whacked by a big honking rock.
This is actually the same thing (Score:3, Insightful)
When a nuclear reaction occurs, energy is released primarily in two ways:
1.) Kinetic/thermal energy carried away the reaction products and free neutrons and electrons.
2.) Radiation (mostly x-rays and gamma rays) emitted directly or by secondary effects like Bremsstrahlung (collisions of particles from method 1).
If there's a lot of extra matter around, like an atmosphere, it absorbs most of this energy, thereby converting it to more conventional effects like a shock wave, and UV/infrared/visible light.
However, in space there's little to absorb and re-emit the radiation or collide with and be displaced by the moving matter, so a far greater amount of the nuclear energy is carried away as radiation. As you said, this heats and vaporizes a thin layer of the surface. The vaporized material flies away, giving an equal and opposite impulse to the bulk of the asteroid. A minor drawback is that most of the energy is wasted, since the radiation is emitted 360 degrees around the warhead.
A similar concept would have a super-powerful laser vaporize small amounts of surface material gradually. This has an advantage of being aimable to get some steering benefit but would require much more forewarning.
I thought it interesting that they proposed six smaller warheads instead of one big one (a 10 MT bomb is not out of the question), but that not only allows them to use existing warheads, but also to have some extra control. I could see them parking the warheads in a safe position a few thousand miles from the asteroid and sending them in one at a time. After each blast, you determine the effect on its orbit, then detonate the next one at an optimized angle and distance to account for uncertainties in the position of the last warhead and the composition and density of the asteroid.