A Plan to Save Mankind

[lajoswinkler]

Speaking of which, there is a movie in which extrasolar planet collides with Earth although it has nothing to do with sci-fi or astronomy for that matter:

http://youtu.be/qczXGTkLRz0

Very good drama about schizophrenia and depression though. Just saying

Call me intrigued.

The solutions may well depend on the asteroid's characteristics. I will make up a scenario. A 250 km rubble pile. A nuclear bomb of 50 MT power would throw off a large amount of fragments. Those fragments, however, would likely not leave orbit due to said objects gravitational influence. Now, a 250 km differentiated rock with a consolidated surface and interior. It has a Crust, mantle and core. It is of much higher density than said rubble pile. A 50 megaton bomb will create a nice crater, but nothing much will be thrown out of orbit, if at all.

250 km rocky object would probably have a partially differentiated interior. It's too large to be just a rubble pile, and too small to be fully formed.

This is Juno, an object with similar dimensions to out hypothetical planetoid.

It is not round, but there was probably some melting in its interior in the early stages.

50 MT nuclear bomb will not disperse even a smaller rubble pile. That's not how nuclear weapons work in vacuum. They can only give off heat radiation which can heat up the surface and then it can vaporize so spallation occurs, making a push through reaction force.

There's no air to make an impulse, a push. Even if there was air, 50 MT is not nearly enough to damage large objects. Nukes aren't that powerful. They look spectacular, though.

[mdatspace]

Call me intrigued.

250 km rocky object would probably have a partially differentiated interior. It's too large to be just a rubble pile, and too small to be fully formed.

This is Juno, an object with similar dimensions to out hypothetical planetoid.

It is not round, but there was probably some melting in its interior in the early stages.

50 MT nuclear bomb will not disperse even a smaller rubble pile. That's not how nuclear weapons work in vacuum. They can only give off heat radiation which can heat up the surface and then it can vaporize so spallation occurs, making a push through reaction force.

There's no air to make an impulse, a push. Even if there was air, 50 MT is not nearly enough to damage large objects. Nukes aren't that powerful. They look spectacular, though.

Oh. So nukes are out. Figures. I was making a scenario. However, there are some completely differentiated asteroids(4 Vesta).

A 250 km rock would have likely undergone internal heating early in its history. Most of the large rocky asteroids and planetesimals(Over 250 km) must have undergone some degree of internal heating and partial differentiation. Some asteroids have undergone more or less full differentiation(4 Vesta). Vesta is also unique as it has had magmatism early in its history. It is pretty close to a terrestrial planet in composition and internal structure.

But back to the point.

You can't destroy a 250 km rock by blasting off material. You can blow up a 5 km rock with enough force(That would cause it to fragment into equally deadly asteroid fragments). Debris blasted off of a 250 km partially differentiated rock will simply fall back to the ground.

Edited November 6, 2013 by mdatspace

[J.Random]

This is Juno, an object with similar dimensions to out hypothetical planetoid.

You've got your numbers wrong - as many people in this thread, it seems. When you're looking for asteroids "size of Moho", keep in mind that most search results will give you size as diameter. 250km is Moho's radius, so any mass you've predicted you may want to multiply by 8.

Edited November 6, 2013 by J.Random

[Tarrow]

50 MT nuclear bomb will not disperse even a smaller rubble pile. That's not how nuclear weapons work in vacuum. They can only give off heat radiation which can heat up the surface and then it can vaporize so spallation occurs, making a push through reaction force.

There's no air to make an impulse, a push. Even if there was air, 50 MT is not nearly enough to damage large objects. Nukes aren't that powerful. They look spectacular, though.

Generally true - there's precedent for getting around that though. The ol' Orion design used reaction mass attached to a nuke to provide propulsive force. The idea was the nuke went off and threw a mass of (presumably vapourised / plasma) tungsten at a pusher plate to push the ship away from the detonation point.

[DaveofDefeat]

There's been some development in shaped charged nukes, might be a little better.