Can a high energy kinetic impact stimulate nuclear reactions?

[essenmein]

I apologize in advance if this is in the wrong forum, I have no idea where this question would really sit.

A number of proposed theoretical weapons, and a concept often used in science fiction, describe a satellite launched, or rather dropped, rod that would gain large amounts of kinetic energy on re entry and the subsequent impact would be rather destructive.

The more recent USAF "rods from god" idea claimed explosive energies in the range of a small tactical nuclear weapon without the fall out from 20ft long 1ft diameter tungsten rods.

Which got me thinking, would there be enough energy to cause some level of nuclear activity releasing radiation (xray/gamma) or cause some level of nuclear reactions leaving some unstable isotopes?

What about a high velocity space originating impact like the Shoemaker–Levy 9 hit on Jupiter? (Estimated release of about 6,000,000 megatons of TNT)

(I'm thinking macro level kinetic impact, at the particle level its all about impacts...)

 

[Drakkith]

No, these kinds of impacts have virtually no chance of causing nuclear reactions. While the bulk energy of the impact is very, very large, this is mostly because of the large mass of the objects. At the atomic and subatomic scale the particles simply aren't moving quickly enough and don't have nearly enough energy to undergo nuclear reactions.

Even the temperature of the impacts is too low to cause nuclear reactions. The Shoemaker-Levy 9 impacts are estimated to only have been about 24,000 K, compared to the 15 million K required in the core of the Sun for proton-proton fusion.

 

[mfb]

At orbital velocity things have a few times the energy explosives release. 5 times, 10 times, 20 times - depends on the explosive you use as comparison. But it's still comparable. Things can get a bit hotter but nowhere close to the conditions you need for fusion.

You can get a nuclear reaction from things colliding at high speed, but you need a particle accelerator (or radioactive decay) for that. Some neutron sources do this routinely, shooting tritium on deuterium for example.

 

[member 656954]

and a concept often used in science fiction

Indeed Allegedly, sci-fi author Jerry Pournelle described the concept of hypervelocity orbital strikes but I've no doubt the idea occurred to others...or would have during the fraught 1950s.

I used the 'Rods from God' concept in a sci-fi story, which involved a lot of reading to understand the design parameters, but for a nuclear strike I had to invent rods that were nuclear-bomb tipped. Otherwise, while a tugsten rod makes a mess dropping in from orbit, it's not nearly enough to cause a nuclear explosion.

So, a 10,000 kg rod traveling at 10,000 m/s at ground level packs a punch of around 6 E¹¹ Joules. For reference, the Hiroshima bomb apparently released about 6.8 E¹³ Joules and newer designs are considerably more powerful. But as @mfb noted, they don't "go nuclear" on impact. And thank goodness, otherwise meteorites could cause nuclear explosions!

 

[Vanadium 50]

nuclear activity releasing radiation (xray/gamma)

As pointed out earlier, you won't get anything nuclear. You probably will get a few x-rays, as even lightning produces x-rays. Indeed, you may even get lightning.

 

[essenmein]

Thanks for the responses!

 

[essenmein]

Indeed Allegedly, sci-fi author Jerry Pournelle described the concept of hypervelocity orbital strikes but I've no doubt the idea occurred to others...or would have during the fraught 1950s.

Yeah he is the cold war "Project Thor" guy!

 

[cmb]

Have you guys seen 'First Light Fusion'?

They are researching what the OP is proposing (well, not from a falling object, but an EM accelerated copper 'bullet' into a plastic target).

https://firstlightfusion.com/