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Comment by no_butterscotch | Hacker News Reader

I'm always surprised we don't take these threats more seriously.

"But we have enough problems down here that need fixing!", "The odds of all civilization being destroyed by that asteroid is only .5%!", "It will cost too much and the odds are low"

You'd think protecting all the things we hold dear, family, culture, art, friends, the future - would be a priority.

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Apart from the really tiny ones, there's nothing we can do.

Tens of thousands of hydrogen bombs can deflect something big.

You don’t even need that. A solar panel and an ion drive will work wonders over time. Heck a solar sail would do the trick.

No, they can't.

You need momentum, and no explosion can provide any global momentum.

Sure they can. They blow a thousand tons of surface off.

No explosion can modify the total momentum.

You don't need to modify total momentum in order to divert the course of an object. Think about how a combustion engine works.

Imagine an asteroid made of ice. detonate a nuke near its surface. Super heated steam will eject from the surface at high speeds. Momentum conserved, and energy from the nuke absorbed by the water and turned into kinetic energy.

I do think we should be "protecting all the things we hold dear, family, culture, art, friends, the future", which is why I prioritise eg. climate change, it is a far greater threat.

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