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The Tunguska Event

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Re: The Tunguska Event

#11

Post by creshal »

mrfusion wrote: post #4

I'm curious if we could mine in areas where large asteroids impacted and gets lots of minerals. Why do asteroid mining if we already have a few in the ground?

That's where meteoric iron comes from: https://en.wikipedia.org/wiki/Meteoric_iron

Two problems with this:

• There's not that many meteorites to go around.

• Elements more volatile than metals (say, water) boil off and/or ablate off during atmospheric entry. If we want to have those, we'll need to mine them in space and shield them during re-entry.

That is assuming we even want to bring those minerals back to Earth. Most proposals intend to use them in-situ to supply spaceborne operations – theoretically, launching the equipment necessary to strip-mine an asteroid is vastly cheaper than sending up the same amount of raw resources. If we can refine those resources efficiently enough in space, things like the ISS or Lunar bases become a lot cheaper.

(Practice is, as always, a lot more complicated.)

Re: The Tunguska Event

#12

Post by simonh »

mrfusion wrote: post #4

I'm curious if we could mine in areas where large asteroids impacted and gets lots of minerals. Why do asteroid mining if we already have a few in the ground?

One factor is that we can choose which of perhaps hundreds of thousands of asteroids are worth mining, while with past impacts we only get what we happen to have been given.

Re: The Tunguska Event

#13

Post by mikeash »

gaur wrote: post #3

The scaling with meteor size is impressive. A 100 m object will flatten some trees in Siberia. A 10 000 m object will kill 75% percent of all species on the planet (the KT event).

Keep in mind that when taking about the diameter of a three dimensional object, the amount of stuff scales with the cube. The second one is a million times more meteor.

Re: The Tunguska Event

#14

Post by adrianN »

grondilu wrote: post #10
amelius wrote: post #5

> Given a long enough time period, there is a nearly 100-percent chance an asteroid large enough to destroy most life on Earth will impact our planet. No worries. Since quantum mechanics dictates that, given enough time, anything can happen, we can also say that given a long enough time period, life will spontaneously reappear.

A more interesting question is : what kind of delay is worth worrying about? I mean, for instance it is known that life will remain possible on Earth for about 500 million years, after which the Sun will be too bright. We don't seriously worry about it, since so many things can happen in half a billion years that it does not make much sense to try to plan or predict anything in such a timeframe. Similarly, I personal…

Eventually you'll have to start worrying about very small but existential risks if you want any chance of preventing them. If the potential costs are as huge as they are with meteor impacts, I think the expected value of preparation is big enough.

Re: The Tunguska Event

#15

Post by EGreg »

elorant wrote: post #9
gaur wrote: post #3

The scaling with meteor size is impressive. A 100 m object will flatten some trees in Siberia. A 10 000 m object will kill 75% percent of all species on the planet (the KT event).

The problem with the latter is that it will cause a nuclear winter. So that 75% will not die instantly but in 2-3 years after the impact. Add an order of magnitude or even half of that and then you have an extinction level event. It could kill organisms even at microbe level.

Ok simple... figure out what will disperse all the ash to prevent the nuclear winter!

Lets start testing this stuff now... may also solve the greenhouse gas problem.

Re: The Tunguska Event

#16

Post by masklinn »

saiya-jin wrote: post #8
krylon wrote: post #6

Earlier quoted context omitted.

One interesting detail I found, I think, on Wikipedia, is that if the meteor had hit about four hours later, due to Earth's rotation, it would have roughly hit Saint Petersburg. If such events happen so frequently, we're pretty lucky so far. Given that much of Earth is covered in water, I could imagine a lot of these simply hit the ocean, but I don't know what would happen if it hit close to the coast.

a simple hit of ocean might be more devastating than hitting uninhabited parts of taiga. think about massive tsunami (at least that's what I would expect, depending on the impact force of course)

> think about massive tsunami (at least that's what I would expect, depending on the impact force of course)

You'd need something way more powerful than the Tunguska event; ignoring that Tunguska was most likely an airburst (not an impact), its estimated yield was about twice the Castle Bravo yield which did generate relatively inconsequential waves compared to the rest of its issues.

A "true" tsunami requires absolutely ridiculous amounts of water displacements, that doesn't happen with anything short of existential-risk impactors. Operation Hardtack confirmed that nuke-level energy didn't come close: there isn't enough displacement and that displacement is very temporary.

Re: The Tunguska Event

#17

Post by [deleted] »

elorant wrote: post #9
gaur wrote: post #3

The scaling with meteor size is impressive. A 100 m object will flatten some trees in Siberia. A 10 000 m object will kill 75% percent of all species on the planet (the KT event).

The problem with the latter is that it will cause a nuclear winter. So that 75% will not die instantly but in 2-3 years after the impact. Add an order of magnitude or even half of that and then you have an extinction level event. It could kill organisms even at microbe level.

[deleted]

Re: The Tunguska Event

#18

Post by gus_massa »

saiya-jin wrote: post #8
krylon wrote: post #6

Earlier quoted context omitted.

One interesting detail I found, I think, on Wikipedia, is that if the meteor had hit about four hours later, due to Earth's rotation, it would have roughly hit Saint Petersburg. If such events happen so frequently, we're pretty lucky so far. Given that much of Earth is covered in water, I could imagine a lot of these simply hit the ocean, but I don't know what would happen if it hit close to the coast.

a simple hit of ocean might be more devastating than hitting uninhabited parts of taiga. think about massive tsunami (at least that's what I would expect, depending on the impact force of course)

Some similar analysis: "Mariana Trench Explosion" https://what-if.xkcd.com/15/

I think that if the asteroid is big enough to make a massive deadly tsunami, it will also create a very big mess if it hit the land.

Re: The Tunguska Event

#19

Post by rikkus »

amelius wrote: post #5

> Given a long enough time period, there is a nearly 100-percent chance an asteroid large enough to destroy most life on Earth will impact our planet. No worries. Since quantum mechanics dictates that, given enough time, anything can happen, we can also say that given a long enough time period, life will spontaneously reappear.

Anything can happen != Everything will happen

A universe of infinite possibilities does not have to include a particular possibility or set of possibilities.

Re: The Tunguska Event

#20

Post by sillysaurus3 »

adrianN wrote: post #14
grondilu wrote: post #10

Earlier quoted context omitted.

A more interesting question is : what kind of delay is worth worrying about? I mean, for instance it is known that life will remain possible on Earth for about 500 million years, after which the Sun will be too bright. We don't seriously worry about it, since so many things can happen in half a billion years that it does not make much sense to try to plan or predict anything in such a timeframe. Similarly, I personal…

Eventually you'll have to start worrying about very small but existential risks if you want any chance of preventing them. If the potential costs are as huge as they are with meteor impacts, I think the expected value of preparation is big enough.

The way to do this is to make it profitable to worry about it.

Some say that certain asteroids are worth trillions. While they're probably not worth quite that much, they're a pretty penny. Investors might be interested in a company designed to capture and harvest asteroids.

It will probably take a few centuries before that's a possibility, but it's interesting that it's probably just a matter of time before it doesn't sound so crazy.

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