Asteroid killing/deflection Mega Thread (Nuclear Bomb Saving Earth From an Asteroid)

[Wally]

How a Nuclear Bomb Could Save Earth From an Asteroid

A well-placed nuclear explosion could actually save humanity from a big asteroid hurtling toward Earth, just like in the movies, a new study suggests.

Scientists at Los Alamos National Laboratory, a United States Department of Energy facility in New Mexico, used a supercomputer to model nukes' anti-asteroid effectiveness. They attacked a 1,650-foot-long (500-meter) space rock with a 1-megaton nuclear weapon — about 50 times more powerful than the U.S. blast inflicted on Nagasaki, Japan, to help end World War II.

The results were encouraging.

"Ultimately this 1-megaton blast will disrupt all of the rocks in the rockpile of this asteroid, and if this were an Earth-crossing asteroid, would fully mitigate the hazard represented by the initial asteroid itself," Los Alamos scientist Bob Weaver said in a recent video released by the lab.

In the 3-D modeling study, run on 32,000 processors of the Cielo supercomputer, the blast went off at the asteroid's surface. So the nuke likely wouldn't have to be deposited deep into a threatening space rock, a dangerous job Bruce Willis and his astronaut crew tackled in the 1998 film "Armageddon."

Weaver stressed that nuclear bombs would likely be deployed only as a last resort, if an impact loomed just months away. And other researchers caution that a nuclear blast might have negative side effects, such as sending a hail of many small space rocks toward Earth instead of a single big one.

If humanity had more notice of an impending impact, there are several other asteroid defense strategies we might be able to employ, scientists have said.

For example, we could send a robotic probe out to rendezvous and ride along with the potentially dangerous asteroid. The spacecraft's modest gravity would exert a tug on the space rock as the two cruise through space together. Over months or years, this "gravity tractor" method would pull the asteroid into a different, more benign orbit.

We have the know-how to pull off such a mission. Multiple probes have met up with rocks in deep space, including NASA's Dawn spacecraft, which is currently orbiting the huge asteroid Vesta. And in 2005, Japan's Hayabusa probe plucked some pieces off the asteroid Itokawa, sending them back to Earth for analysis.

Humanity could also simply slam the rendezvous craft into the asteroid, relying on brute force rather than a gentle gravitational tug to push it off course. This impactor approach would not be as precise as the gravity tractor technique, researchers say, but it could still do the job under certain circumstances.

We've demonstrated the ability to accomplish this more aggressive mission as well. In 2005, for example, NASA sent an impactor barreling into the comet Tempel 1 to determine the icy object's composition.

Discussions about asteroid deflection aren't just academic exercises. Huge impacts are a part of our planet's history; one wiped out the dinosaurs 65 million years ago, and it's just a matter of time before another big space rock lines Earth up in its sights, astronomers say.

Source: Space.com

 

[mojoey]

sure, because nukes have never caused problems

 

[Luke Skywalker]

sure, because nukes have never caused problems

If not handled properly, they always cause problems, alot of problems.

 

[RisingFury]

This is just a study, mojoey. It's good to have several different strategies well documented, but not all work the same way and not all can be pulled off because of the circumstances.

Gravitational tractor is probably the best option, but it requires that you detect the threat some 10 years in advance, to give enough time to build the mission, launch it, rendezvous and to give the tractor enough time.

An impactor would work only in cases where you can get a high relative velocity impact.

Any sort of solar sails or other strategies that exploit small forces caused by different effects also take years.

A nuclear detonation at the surface can - according to this study - punch enough delta-v and also at a short notice, but it has its own risks. You risk splitting the object into smaller components and not deflecting its path, or you risk vaporizing a large chunk of it, turning it into dust, but not deflecting its trajectory. In that case, the energy is still there. The particles would burn up in the atmosphere and you'd have the equivalent of a hundred suns in the sky for several hours.

 

[MattBaker]

Gravitational tractor is probably the best option, but it requires that you detect the threat some 10 years in advance, to give enough time to build the mission, launch it, rendezvous and to give the tractor enough time.

Well, I think the "detection in advance" thing is nothing special, we had found Apophis already, a 270m-rock that might hit the earth in 2023, so we have 10 years, even with smaller rocks like Apophis.
But on the other hand, big asteroids, that are easy to find and are a real threat to earth, have a much higher mass, so the gravitational method becomes useless.

I see two major problems with "asteroid-smashing/pulling":
1. Political problems: Who will launch that bomb/probe, who will pay for it
2. Infrastructural problems: How can we launch a 20t probe to some asteroid within one or two years, which rocket could lift such a mass?

 

[Zatnikitelman]

You risk splitting the object into smaller components and not deflecting its path

Back on the M6 forums, I started a thread titled "Shotgun effect, so what?" and in the end, someone used the gravity simulator and created a collection of fragments with different velocities to simulate the shotgun effect. Only a small handful of fragments reached Earth, the rest went past on either side. A blast wouldn't simply keep a grouped up bunch of fragments flying towards Earth, they'd go flying.

 

[ED_4]

Sure send enough of our multimegaton missiles at it and it will have to move. That much force on a moving rock should be able to at least send it somewhere other than straight at us.

That is so long as it's not enough to split it into several smaller pieces still hurtling towards us. I only wish that by then I wouldn't need to :bailout:.
We really have no where else to go if Earth gets devastated. What space? It's still a very harsh environment compared to what mother Earth has to protects us from all the radiation and what not that it gets from space.

 

[Napalm42]

On top of that, if the impact is too close to Earth, we basically lose all satellites not behind the Earth at the time from the EMP wave.

 

[Artlav]

On top of that, if the impact is too close to Earth, we basically lose all satellites not behind the Earth at the time from the EMP wave.

If it is that close, we are talking about DV on the order of hundreds of m/s to deflect the asteroid. No nuke can provide that, either for the whole rock or for most of it's pulverised fragments.

 

[Urwumpe]

It is also important to note which kind of asteroid they used as assumption of the simulation.

 

[Hlynkacg]

As I recall there was a brief time where it was believed that Icaraus 1566 might strike the Earth in 1967.

MIT undertook a study on behalf of NASA that concluded that the asteroid could be deflected using hardware already on hand. Specifically 4 of the Saturn Vs slated for Apollo.

Based on mass and density measurements of Icarus available at the time MIT concluded that 3 or more 100 mt bombs detonated alongside the asteroid 4 months prior to impact could impart enough lateral drift for it to miss Earth.

Obviously improved orbital tracking rendered the plan unnecessary, but it wasn't that far-fetched either.

---------- Post added at 05:34 PM ---------- Previous post was at 05:29 PM ----------

sure, because nukes have never caused problems

On the whole I'd say that Nukes have been a boon to society.

Leaving aside the benefits of nuclear power the years since the the end of WWII has been the longest stretch of peace between major powers in a millennium and I'd argue that nukes are largely to blame.

 

[Ghostrider]

Sure send enough of our multimegaton missiles at it and it will have to move.

Too bad we don't have multimegaton missiles. Most strategic warheads are in the 500 kT yield range and they're armed through accelerometers and radar altimeters, and mounted on top of ballistic missiles. Hardly the kind of weapons you want to use to hit an incoming rock moving at hyperbolic speeds.

Hitting it with more rocks, not square in the center but with multiple glancing blows may be more effective. A good mass driver at L3 could to the trick.

Why is there no love for mass drivers at Lagrangian points? They're cooler than nukes. Not as cool as colony lasers but hey...

 

[T.Neo]

OMG you can't nuke an asteroid! That won't work! Nukes are bad! You'll never be able to nuke an asteroid and get it to work!

The asteroid will break up and won't be deflected and it'll spin out of control and become radioactive and it'll move onto a new trajectory and we won't be able to track it and it'll be more difficult to mitigate...

...and it'll start emitting flying ponies of DEATH that will target specific sites of interest on Earth with laser cannons in their mouths and it'll fly around and destroy satellites one by one and shine lights in the eyes of airline pilots at night and destroy fish stocks and the flying ponies of DEATH will crash into mountains and birds will start eating trees and there'll be Easter Island Moai Rampages and they'll miscalculate the warp factor on their missiles and people will start selling their left socks and it'll practically be an apocalypse...

 

[RisingFury]

Back on the M6 forums, I started a thread titled "Shotgun effect, so what?" and in the end, someone used the gravity simulator and created a collection of fragments with different velocities to simulate the shotgun effect. Only a small handful of fragments reached Earth, the rest went past on either side. A blast wouldn't simply keep a grouped up bunch of fragments flying towards Earth, they'd go flying.

Yes, if all goes well, that's to be expected. The problem appears when you break the asteroid into large chunks and blow away one of those large chunks at large velocity. That one than takes most of the momentum, with the rest getting very little.

Kinda like when a billiard ball strikes a bunch of other balls, but only one or two go flying out.

 

[Ghostrider]

...and it'll start emitting flying ponies of DEATH that will target specific sites of interest on Earth with laser cannons in their mouths...

You know, the way you're saying it, one could almost think it would be a Bad Thing.

 

[Izack]

Gravitational tractor is probably the best option, but it requires that you detect the threat some 10 years in advance, to give enough time to build the mission, launch it, rendezvous and to give the tractor enough time.

What sort of mass would you suggest such a tractor have? You mentioned something about 10 tonnes for the albedo coating spacecraft earlier in the thread; a gravitational tractor must need some awesome mass to be effective within ten years, no?