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Is it possible to detonate a nuclear bomb in space? If possible, then what will happen? In the Armageddon movie we watched that, after discovering that an asteroid the size of Texas is going to impact Earth in less than a month, NASA recruits a team of deep core drillers to drill and blast a nuclear war-head. Is it possible?

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    $\begingroup$ Actually, in real life, destroying an asteroid would be a very bad idea - after explosion, we'd have thousands of spreaded objects instead of one huge. If these are not small enough to burn during atmospheric entrance, that would be fatal. $\endgroup$ Sep 19, 2014 at 12:10
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    $\begingroup$ A short answer: yes, it is possible to detonate the warhead in space, on or inside an asteroid. The effects would be qualitatively different in all three cases. $\endgroup$ Sep 19, 2014 at 12:51
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    $\begingroup$ It's been done - Starfish Prime in 1962 en.wikipedia.org/wiki/Starfish_Prime $\endgroup$ Sep 19, 2014 at 14:47
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    $\begingroup$ @ZoltánSchmidt: Even if they do not burn up completely, the individual parts do experience far more air resistance than the original asteroid. That means a lot more energy is dissipated as heat, leaving far less energy at the impact points (which are also now distributed in time and space). A lot of the bad effects are highly non-linear. Furthermore, if done early enough many fragments would miss earth outright. $\endgroup$
    – MSalters
    Sep 22, 2014 at 11:28
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    $\begingroup$ It's been done, and the main lesson we learned was that a nuclear explosion in space generates a massive EMP that damages power lines and communications networks on Earth. So this would be an option of last resort, not a routine technique for e.g. asteroid mining. $\endgroup$
    – Hobbes
    Nov 3, 2017 at 17:54

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You can detonate nuclear bombs in space, it's been done several times. There are technical challenges to it but nothing too complex.

In an atmosphere much of the damage from a nuclear weapon is from the blast wave which is caused by the heat and pressure of the explosion. This wave goes out from center of the explosion, and then back again as the pressure drops. This is why most nuclear weapons are designed for an air burst rather than a surface burst in order to maximize the destruction caused.

A nuclear weapon in space has a different effect than one detonated in the atmosphere or underground as there's no matter for the explosion to push against. What will happen is a burst of radiation and plasma which disperses evenly outward from the detonated device.

What would happen if you detonated a nuclear device inside an asteroid? That depends on the composition and size:

  • If it's small enough it could be completely vaporized, however if it's that small it's probably not a danger
  • It could blast it into many pieces, which would be a bit better than one big asteroid as it gives the smaller pieces a better chance of burning up in the atmosphere, although the earth would get pelted by many smaller impacts rather than one big one, spreading damage over a wider area
  • The asteroid could contain the blast and remain intact, or the force of the explosion could be lost through fissures in the body of the asteroid and also leave it intact. It is extremely unlikely that it would break into 2 clean pieces predictably as in that (awful, awful) movie.

A nuclear blast theoretically could be used to deflect an asteroid by being detonated close to it, the heat and radiation could ablate the side of the asteroid facing the explosion causing it to change course. The effect is likely to be small and would need to be achieved while the asteroid is a considerable distance away. We would need many years' warning to achieve this, which is why it is pretty important that we start tracking asteroids and comets far better than we do now.

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    $\begingroup$ That awful movie? Just because it was inaccurate scientifically doesn't mean that other wise it's plot elem... well there's always the character devel... umm I mean, the special effects were pre... damn it really was a terrible movie... $\endgroup$
    – corsiKa
    Sep 19, 2014 at 18:08
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    $\begingroup$ @corsiKa there's always the soundtrack...wait, no, it was terrible. $\endgroup$ Sep 19, 2014 at 19:30
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    $\begingroup$ There's always the acting. Oh wait.... $\endgroup$
    – GdD
    Sep 19, 2014 at 22:31
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    $\begingroup$ Many small asteroids isn't worse than one big asteroid. The breakup exposes much more surface while the weight remains the same. So the pieces are subject to way more aerodynamic braking, with a good chance they'll burn up instead of hitting the ground. You'll also spread the impact over a larger area, spreading the damage around but limiting the amount of damage in one place. $\endgroup$
    – Hobbes
    Sep 20, 2014 at 8:59
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    $\begingroup$ I know I'm late, but how did no one mention the fact that Liv Tyler is in the movie? She alone almost makes it worth watching. $\endgroup$ Mar 31, 2016 at 19:12
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Is it possible?

As depicted in that awful movie? No. The concept in general? Yes. A nuclear standoff explosion is widely regarded as the best, most realistic approach to diverting an incoming asteroid or comet, assuming some minimal amount of lead time. Weeks or months do not qualify as "minimal". We need a couple of years, at least, even with nukes.

A nuclear standoff explosion involves exploding a nuclear bomb at some distance away from the target object. (Note well: This is exactly how our every country that has nuclear weapons plans to use them, and has tested using them. This is a Technology Readiness Level 9 concept.) More than half of the radiation and neutrons created by the explosion go off into space, but a good portion will bathe the asteroid/comet with gamma rays, X-rays, and high energy neutrons. This will cause the outer layer of the part of the asteroid/comet that faces the bomb to vaporize. It is this secondary explosion that provides the needed impetus to divert the object.

We cannot divert all incoming objects. The asteroid that exploded over Chelyabinsk in early 2013, or a dinosaur killer comet that we don't see until months prior to impact: Those are problems for some future generation to solve. Those Chelyabinsk-level objects are far too hard to see. Diversion is not possible if we can't see the incoming object ahead of time. Suppose a dinosaur killer by some fluke of its trajectory manages to sneak up on us until just months before impact. We're already dead. At some point there is nothing we can do except say goodbye to one another.

What we can solve using current technology, or reasonable extensions to current technology, are potential impactors that we first detect years prior to the impact. The nuclear option is the only viable approach if we detect the impactor less than a decade prior to impact. With that short of a lead time, a non-nuclear approach would require hundreds to millions of launches and hundreds to millions of cooperating vehicles. A nuclear approach would require very few launches, typically, just one.

Non-nuclear approaches might work if we detect the impactor several decades prior to impact and if we take action soon after detection. That action includes spending a rather sizable chunk of money on technology that is not quite ready for prime time, and that spending needs to start soon after detection. The problem here is that that multiple decades of lead time is more than enough time for the uglier side of humanity to raise its ugly head. "Why should we spend such huge amounts of money to solve a problem that won't be a problem for half a century when we have so many pressing problems right now?" So we won't spend the requisite amounts of money. We'll instead twiddle our thumbs. We'll wait and wait until the problem is a decade away or less, making the nuclear option the only viable option.

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    $\begingroup$ Another factor that comes out way in favor of the nuclear approach: You don't need to match orbits, all you need is an accurate fusing system. It doesn't matter if the bomb is going 50 km/sec relative to the target, you'll get the same nudge as if it was simply floating nearby. If the threat is a NEO this isn't that big a deal. If the threat is a comet it's a very big deal indeed. $\endgroup$ Sep 19, 2014 at 22:02
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    $\begingroup$ @LorenPechtel - Exactly. In fact, diverting a comet with a gravity tractor is a very dubious undertaking for that very reason. $\endgroup$ Sep 19, 2014 at 22:16
  • $\begingroup$ Our space technology is very young, not much older than the 50 years lead time you cite. So it's reasonable to expect that in additional 50 years, much better technology will be developed even without a huge world-wide expenditure. And so it is reasonable to wait for better technology to arrive and save us, rather than relying on immature and unproven options we have. This argument will slowly fade as space technology matures and further advancements become smaller and smaller. $\endgroup$ Dec 13, 2015 at 3:43
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    $\begingroup$ @Loren Pechtel : if the relative speed is 50 km/s and the acceptable position error is 10 m, the timing error should be less than 200 µs. But if the nuke should explode in a precise distance and direction to the target, you need not only very precise timing, you also need a very precise orbit of the nuke. Otherwise the nuke is never at the desired position relative to the target during the passage. Course corrections in the last moment would require a lot of delta-v and fuel. Early course corrections need very precise for both orbits. $\endgroup$
    – Uwe
    Nov 2, 2017 at 19:20
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    $\begingroup$ @Uwe I do agree the positioning requirements are pretty tight but that's an awful lot easier to do than putting that kind of delta-v on the rocket. And note that while the vertical placement might have that sort of requirement the horizontal will not--a nudge that's a bit off the desired axis still applies most of it's force in the right direction. And you should be able to get the required accuracy if you use two probes--think of how Deep Impact worked, but the other way around--the non-impacting part goes ahead and gets a precise location. $\endgroup$ Nov 3, 2017 at 21:43
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I did some research on the effects of nukes on asteroids here: Using nukes to push an incoming meteoroid off course

In summary, a single large nuke could vaporize the majority of asteroids, if detonated at the core. Even if chunks survived, they'd be blown off course.

And to answer your question, no, we can't travel to one in under a month and perform a soft landing. We have no idea how to mine to the core of one. We even don't really know if asteroids are solid or just loose piles of gravel.

Within a month, it's a challenge but we could probably mount a couple of nukes, or one big one, on a rocket and have it detonate near the surface of an incoming asteroid. This is likely to vaporize most asteroids, especially if they are piles of gravel.

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I just want to add a couple of points.

First, if the asteroid is really "the size of Texas" then it's pretty much game over. If you think about it, single nuclear weapons destroy entire cities, but not entire states. An asteroid the size of Texas would be massive enough for its gravity to pull it into a sphere, and there would be no hope of blowing it up, splitting it into two diverging parts, or even really deflecting it. Fortunately, we have looked, and there is nothing that big in an orbit that can hit the earth. (There could be something way out in the Oort cloud, but that's very unlikely.)

Second, although apparently this isn't relevant to Armageddon (but perhaps it is for Deep Impact), for an asteroid large enough to cause global devastation, breaking it up into pieces that burn up in the atmosphere is not as helpful as you might think. The amount of kinetic energy is the same, and all of that energy is converted into heat. You could get much of the sky briefly glowing like the sun, and the planet covered with forest fires.

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  • $\begingroup$ It's been years since I've seen that movie, but don't they address most of that in the plot? The plan isn't to blow up or deflect the asteroid, but to split it in half and have the force of the explosion push the two halves apart so they miss earth. Which isn't to say that's any more realistic than just blowing it up... $\endgroup$
    – paulmrest
    Apr 20, 2022 at 2:49
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    $\begingroup$ I forgot that. Updated. $\endgroup$ Apr 20, 2022 at 4:19
  • $\begingroup$ I've always wondered what the rules are for comparing two dimensional objects (Texas) with three dimensional ones (asteroids). $\endgroup$
    – rghome
    Apr 20, 2022 at 11:54
  • $\begingroup$ My interpretation: The average silhouette, viewed from a random direction, has about the area of Texas. $\endgroup$ Apr 20, 2022 at 12:38

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