Mike Radmore

retired

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Asteroid Strike against Earth: Would an explosion in space, even a nuclear one, behave as they do on Earth?

My understanding of the way explosions destroy things is that the explosive materials produce intense heat which heats up the surrounding air which expands and it is the resulting shockwave that does the damage.
My understanding of space is that there isn't any air.
So will any form of explosion in space be able to push an asteroid off its trajectory?

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    Sep 21 2011: no, explosives create their own gas, they don't rely on air to expand. however it is true that air or water delivers the blast energy to the target. in space, only the created gas expands, and when reaches the asteroid, it exerts some push on it. but considering the tiny tiny mass of the gas, and the huge mass of the asteroid, it won't do much.

    things are a little better with a nuke. the immense heat will evaporate large amount of the asteroid mass itself, and as it expands, pushes the asteroid in the opposing direction. it is enough? depends on the distance and the size of the rock. if the asteroid has some hundred million or a few billion kilometers to travel, even a small trajectory change can be enough. if it is inbound already, we need a larger change.

    most likely, a smart solution would bring better results than the brute approach of a bomb. delivering some rocket fuel and a rocket to the asteroid, and starting to slow-push it over a long time can be more feasible.
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    Sep 21 2011: Not all fires burn due to "air" - gas form of oxygen. Oxidizers can be pre-packaged into an explosive - e.g. gun bullets. Just drop some Lithium or Sodium or Cesium into water. You've never seen water burn so bright. :-) My guess is that depending on the type of the matter we're attacking, we can find explosions which work together with the matter in the stellar body to destroy it. You get to more of an issue with soft-bodies commets, which are just a gravity-held bulk of dust, ice, small rocks, etc, and not what we define as a solid rock. Smaller explosions would just be absorbed into the flacid structure.

    I would be interested to hear answers from chemists and physicists out there on specific reactions which can create enough matter propulsion to "space shock waves". You can also always drill the explosive into the rock before you blow it. :-) Heat and expand the matter itself, not air around it. Fill the drilled with water, or something denser.