Space rock 'on collision course' with Earth!!!

[KrazyHorse]

Why are you awake?

[Dan Severn]

Oh, dear! The sky is fallin'! Th' sky is fallin'! Literally!


Heh heh heh.

I could shiv a git.

[Bereta_Eder]

How come you always know what time it is in Greece and I don't know what time it is in Canada (Quebec is it?)

I'm writing stuff.

[KrazyHorse]

Because I have some knowledge of geography. I'm at Greenwich-5, you're either at Greenwich+2 or +3...

[Dr Strangelove]

So how big is this thing? The Tunguska rock was supposed to be only about 200 meters diameter. Even a big non-nuclear bomb would blow something that size into easily manageable chunks.

[KrazyHorse]

It's harder on you, I guess...

Canada spans 6 time zones...

[ravagon]

Originally posted by MOBIUS

Thanks Ramo - Tunguska was the one I was thinking of. Damned lucky it hit a totally unpopulated area, it was massive!

The tungaska "meteor" (1908) never actually hit. No impact crater. It exploded in mid air and flattened/irradiated a few hundred sq km IIRC.

A 2km wide asteroid isn't really much of a threat in any case. Not enough mass to serious impact the planets axial tilt or orbit (which could annihilate virtually all life) hence the major threat comes from the primary impact and the projected dust cloud fallout.
High-yield fusion warheads have a blast radius > 2km so even a near miss should be capable of fracturing the body at the very least - hence increasing the surface area over which it absorbs heat entering the atmosphere, thus vaporizing and reducing the size of the fragments and further reducing the impact.

[KrazyHorse]

Originally posted by Dr Strangelove
So how big is this thing? The Tunguska rock was supposed to be only about 200 meters diameter. Even a big non-nuclear bomb would blow something that size into easily manageable chunks.

Not really. You could detonate a few dozen tons of TNT against an asteroid of 200 metres diameter without breaking it up (assuming it's actually solid and not just a loosely-bound pile of rubble).

Remember how big 200 metres is...

[Bereta_Eder]

I have a vague recolection of Greek time being 2 hours ahead of London time...

So we're 7 hours apart.

Memorized.

[Dr Strangelove]

It knocked down trees in an area 30 miles in diameter. Yes, you're right, it did not actually impact the earth.

[KrazyHorse]

Originally posted by ravagon


The tungaska "meteor" (1908) never actually hit. No impact crater. It exploded in mid air and flattened/irradiated a few hundred sq km IIRC.

A 2km wide asteroid isn't really much of a threat in any case. Not enough mass to serious impact the planets axial tilt or orbit (which could annihilate virtually all life) hence the major threat comes from the primary impact and the projected dust cloud fallout.
High-yield fusion warheads have a blast radius > 2km so even a near miss should be capable of fracturing the body at the very least - hence increasing the surface area over which it absorbs heat entering the atmosphere, thus vaporizing and reducing the size of the fragments and further reducing the impact.

2 km is a serious amount of mass. I don't know if even a direct hit with, say, a 20 megaton thermonuke would actually do anything other than crack off a big chunk. I sincerely doubt it would shatter it.

[Dr Strangelove]

Originally posted by Frogger


Not really. You could detonate a few dozen tons of TNT against an asteroid of 200 metres diameter without breaking it up (assuming it's actually solid and not just a loosely-bound pile of rubble).

Remember how big 200 metres is...

How solid would something with such a small gravitational field holding it together be?

[KrazyHorse]

That's why I mentioned the requirement that it not be a rubble-pile (blow on it hard enough and it will dissipate). Many asteroids are actually solid bodies (giant chunk of rock or nickel or iron). They're held together by their EM bonds, not gravity.

[ravagon]

Originally posted by Frogger

2 km is a serious amount of mass. I don't know if even a direct hit with, say, a 20 megaton thermonuke would actually do anything other than crack off a big chunk. I sincerely doubt it would shatter it.

If 2km is the diameter of its major axis then it has a volume of a few million cubic metres. Assuming a relative density of about 5 (I don't remember how reasonable this is I'm afraid) puts the mass at a few billion tons. This shouldn't be sufficient to withstand the stresses of a multi-megaton blast.
Nickel-Iron asteroids may be a little more resilient than Stoney-Irons but not by a great deal.

I may be making too many assumptions of course but I don't think thats too far out.

[KrazyHorse]

Rav, how big a crater does a thermonuke make?