This being a hard science-fiction book, one of my biggest challenges was to figure out how to destroy global civilization without causing the extinction of humankind. It’s a much finer line to balance than I had imagined.

For this story to work, I had to have a catastrophe that was sudden, would cause earthquakes and tsunamis, and could not be anticipated at all - not even by the ever-vigilant preppers, who shouldn’t have the time to make it to their well-stocked shelters, for my story to work.

So, of course, it would have to be an impact. It should have enough kinetic energy to create a 9.6 Richter scale earthquake at Changi, strong enough to cause liquefaction of the reclaimed soil. You see, liquefaction was the only way this object could get buried quickly. Yet, at the same time, the impact needs to be distant enough for the intense heat not to destroy the object that I intended to preserve. Tough to balance.

How do I deliver 10 million megatons of kinetic energy punched deep into the earth to create the kind of earthquake I needed? The obvious answer is an asteroid. Not as large as Chicxhulub impactor that wiped out the dinosaurs, but big nonetheless.

The problem is, an asteroid like that would be noticed long before it got anywhere near to impact. A nickel-iron asteroid traveling at 20km/s (the average speed of a near-earth asteroid) would need to be 3.7km in diameter (that’s 157 tennis court lengths in radius, and weighing as much as 52 trillion cats, for those strenuously avoiding the metric system). That’s humongous. We have systems in orbit that would detect it decades in advance. Enough time to send up Bruce Willis.

So it needed to be small. Less than a 100 meters in diameter to avoid detection. But with the density of a Nickel-Iron asteroid, that gives a mass of about 373,000 tons. Even at the velocity that the interstellar comet 3I/ATLAS is traveling, that’s nowhere enough kinetic energy for the devastation I was planning… I mean, hoping for… I mean… Well, you know what I mean.

The obvious answer is to increase the velocity. It needs to be traveling at around 5% the speed of light. That solves a lot of problems. At that velocity, none of our early warning systems would detect it. It would cross the field of view of ATLAS between frames. To avoid JWST catching it accidentally, I could have it traveling from behind the Sun from the Earth’s perspective, like the Chelyabinsk meteor that we completely missed because of the Sun’s glare. The small size combined with high velocity would ensure that the energy is delivered deep into the Earth’s crust without dissipating at the surface. It was the perfect solution. The Earth would ring like a bell, triggering landslides, volcanoes, and tsunamis.

Unlike the Chixulub event, most of the ejecta will reach escape velocity, taking the excess kinetic energy away instead of heating up the atmosphere, thus avoiding extinction level damage. The ejecta trail would be a stream of super-heated plasma pointing straight up, following the path the meteor had taken. It would look like a pillar of light brighter than the sun, stretching to the heavens.

This is why the book also contains a brief backstory of the meteor that no one got to name - because hard science fiction need to be based on what is possible within the laws of physics, not magic.