Apologies for the bad French pun in the first panel (Lies! I regret nothing!). Couldn't resist. I may try something different next week in terms of updating. While I know the occasional erotic interludes are something of a trademark for this comic, they can be a narrative black hole at times. So I want to get the next few pages uploaded quickly so they don't bog down the story. Normally I don't like to post a lot of pages all at once, because I don't want readers to fall behind, but in this case there's not much to miss. So, I will probably do a multiple page upload at some time next week. At least, that's the current plan. We'll see!
In the movie 'Armageddon (1998),' space cowboys detonate a bomb inside an Earth-threatening asteroid, blowing it in half and saving the world from imminent doom. But how plausible is it that we could blow up an asteroid? Well, recently a group of researchers at Johns Hopkins University did a detailed simulation of just what happens to an asteroid when it fractures… and it's not very promising. Here's the second phase of their simulation, in a three-hour time lapse.
So after three hours, the asteroid (25 kilometers in diameter) is more or less fully reformed, minus a little bit of lost material. Blowing it up does virtually no permanent damage.
So why is that? If you blow something up in space, the pieces should fly apart and keep flying away forever, right? That's one of Newton's laws! Well, okay, sort of. That's only the case when there is no outside force acting on the object in motion. In this case, there is an outside force: gravity.
In the simulation, the asteroid is not entirely obliterated by the impact, so there's still a core of material left behind, and that core exerts enough gravitational pull to vacuum up most of the debris, reforming the asteroid within a few hours.
So all you need to do is completely blow the asteroid apart and that'll do it, right? Well… maybe not. Even if the whole thing is in pieces, those fragments still exert some gravitational pull on each other and will try to reform around their mutual barycenter – their average center of mass. The only way that won't happen is if all of the fragments are blown away with enough force for them to reach escape velocity. Otherwise, it's basically like kicking up a cloud of dirt here on Earth – the particles fly away for a bit, but they eventually fall back to the ground.
So how much energy would it take to completely blow apart a 25 km asteroid so it wouldn't reform? Well, I couldn't find good data on this, so I calculated the gravitational binding energy for a typical asteroid that size and it came out to about 3 septillion joules – that's 3 with 24 zeroes behind it, or about 45 thousand times the energy of every nuclear warhead on Earth. In other words, blowing up an asteroid is not realistically plausible, at least with our current technology. Or I suck at math. But either way, fun stuff to think about.
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