[BenLurkin]

Three mega-tons is a pretty big bomb, yes?

[airborne]

Wouldn’t it be better to nudge it into a safer trajectory?

[I want the USA back]

No bomb. Blasting it into pieces makes it much more difficult to keep track of the pieces and to predict where they will fall.

[rktman]

Gotta ask Bruce Willis and tommy lee jones about how to alter or destroy a comet. Ref Space Cowboys:

https://en.wikipedia.org/wiki/Space_Cowboys

[knarf]

They're flying around in a (relative) vacuum so there is no opposing pressure to an explosion .... I think all you really have to do is FRACK the sumbitch.

Tiny little pieces expanding out and away from the point of detonation.

[Red Badger]

Seems like it would be a lot cheaper just to attach a small rocket to change the rock’s orbit..............................

[freedumb2003]

Don’t you need Clint Eastwood and Tommy Lee Jones?

If not, maybe just have Chuck Norris roundhouse kick it back?

[Celerity]

A bomb powerful enough to eliminate New Jersey should do the trick.

I see what I did there.

[WayneS]

It depends on the size of the asteroid.

[G Larry]

The whole idea is nuts.

If God wants to smite us, He ain’t gonna miss.

[PapaBear3625]

You don't need to vaporize it, you just need to break it up into small enough pieces that it burns up in the atmosphere.

If you hit it with a 1-metric-tonne steel penetrator, going at 30 km/sec, the kinetic energy would be

0.5 * 1000 * 30000² = 4.5 * 10¹¹ joules, which is about 100 tons of TNT

While not of nuclear magnitude, the shock wave from the penetrator would likely shatter the rock better than an explosion at the surface of the rock.

[RayChuang88]

You don’t need a big bomb. Given the size of most asteroids, a small nuke in the 10 kT range would be enough to “nudge” the asteroid to a new orbit that avoids the Earth.

[lurk]

Anything smaller than a bus will heat and break up on entry. It may make a noise like the Russian one a couple of years ago, but not much more.

So all we would need to do is create pieces, not dust.

I doubt we’ll ever do it.

[BobinIL]

Do explosives even work in oxygen deficient atmospheres?

[Mouton]

Well, the tested a 100 MT weapon some time ago, so why take a chance, go for the gusto.

[<1/1,000,000th%]

The Tsar Bomba bomb was 50 megatons.

[JimRed]

Since there is no atmosphere surrounding the asteroid to impart a shock wave, contact will be required. The fireball will vaporize what it contacts and the shock wave through the remaining solid part should fragment the rest.

But then, I’m not a scientist. I didn’t even stay at a Holiday Inn Express last night...

An alternative might be a small lander with a rocket motor attached which can be fired to nudge the asteroid into a “safe” trajectory. Probably cheaper, too.

[VietVet876]

Send the leaders of the following to it and tell them it is theirs to govern. It will fall apart shortly thereafter.
Pick one:

South Africa
California
Baltimore
Venezuela
Chicago

[NorthMountain]

Three mega-tons is a pretty big bomb, yes?

We used to build a lot of them that size. Biggest we ever fielded, as an operational weapon, was the 25MT Mk-41 bomb. It weighed almost 11,000 lbs.

[M Kehoe]

Ivan always thinks big when discussing bombs.

300kt would do the job on an asteroid of that size.

5.56mm