To Nuke an Asteroid, How Powerful a Bomb Do You Need?

Space.com ^ | March 14, 2018 07:40am ET | Mike Wall,

[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.

[Little Pig]

I guess that’s technically true. Most HE rely on the breaking of molecular bonds via shockwave or electric current, and still don’t need to be in an oxygen atmosphere to detonate. Some like actual TNT do capitalize on the oxygen released during the reaction, but that’s not the main source of detonation since an oxygen combustion reaction would be too slow.

[M Kehoe]

Ivan always thinks big when discussing bombs.

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

5.56mm

[Ozark Tom]

Actually some carbon encased steel items survived a virtually point blank experience with the bomb. The stumps of test towers for elevated shots often remained after detonation.

[Ozark Tom]

Enough pieces hitting the atmosphere in a short time span would allow grilling steak at the surface of the Earth without the charcoal.

[Still Thinking]

The rock will probably even provide the kinetic energy if you can park the Rod From God accurately enough or maneuver it laterally in real time.

[Still Thinking]

Mmmmmm.....steak!

[Ozark Tom]

Plastic added as a pusher component provides light atomic weight material which absorbs the bomb energy to form a high density plasma shock-front, which in turn strikes the rock.

[Ozark Tom]

Take a brick of explosive into a vacuum chamber and test that concept.

The shock-front of expanding plasma from explosive will shear steel; and, it doesn’t even notice an atmosphere. The plasma initially is moving at many times the speed of sound in air.

[CaliforniaCraftBeer]

 

good actors trying to read a golden turd of a Hollywood script,
'Meteor' (1979) has a lot of unintentional belly laughs
and an ending that'll have you saying, "idiots got what they deserved".

Full film here (360p resolution):
http://bit.ly/2IpSr15

 

[PapaBear3625]

Enough pieces hitting the atmosphere in a short time span would allow grilling steak at the surface of the Earth without the charcoal.

It would depend on how spread out it was. The Chelyabinsk meteor that hit Russia in 2013 was estimated to be 20 meters wide and produced about 500 kt worth of energy. The meteor in the example would be 10 times as long (200 meters) and thus around a thousand times the mass. So lets call it 500 megatons. Concentrated on one spot, that's a hell of a lot of energy. Spread out over the earth, not so much.

[PIF]

Well, the tested a 100 MT weapon some time ago,

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The Russian Tsar Bomba was scaled back to a mere 50 MT.

[Boogieman]

"Take a brick of explosive into a vacuum chamber and test that concept."

It's already been done:

Explosion in a Vacuum Chamber

"The shock-front of expanding plasma from explosive will shear steel; and, it doesn’t even notice an atmosphere."

The presence of a shockwave at all is an artifact of the atmosphere. A shockwave can only be produced when something is moving faster than the speed of propagation in a medium. This is why sonic booms are produced when you break the speed of sound, and why Cherenkov radiation is produced when particles exceed the (reduced) speed of light when traveling through denser material than a vacuum. Without a medium, there is no propagation speed, and therefore, there can be no such thing as a shockwave. The only shockwaves that can occur in a true vacuum are gravitational shockwaves, since those use space itself as the medium.