Those asteroids...they are the reason, that I'm so lucky lately.

Really puts it all in perspective, doesn't it? ^^

I feel so insignificant. ^^

Sounds like a job for Tom Corbett, Space Cadet!

you'd think NASA would take the time to implement satellites further away from earth so we can probably get a further view and catch these asteroids sooner... maybe around the moon or even Mars.

They actually would if they could--the problem isn't so much a lack of will as it is a lack of funds.

well yeah, I figure it would be a funding issue... but you'd probably think we'd use this as a warning that we need better equipment set up so we can catch this earlier.

For all I know, we're waiting until an asteroid hits a majorly-populated city before world leaders get the hint.

Man, it'd be awesome to watch them try an' shoot a space rock down with ICBMs, lol.

You wouldn't want to shoot it down as much as try and nudge it into a different orbit. And I love your new Talking Carl icon!

*Nods* I know.

And go to  astrofenn, she's doin' 'em for 5 pounds.

You hear about this sort of close encounter happening pretty regularly, these days. Very sobering. But, I wonder, is blowing them up really a serious option? What happens to the debris? What about nuclear fallout (assuming nuclear explosives are used)? Do we even have the technology precise enough for delivery, anyway?

A part of me wonders if the reason we as a society don't thoroughly surveil the sky is (at least in part) because our options for action if we do find a problem are pretty unwelcome themselves.

No, you wouldn't want to blow it up at all. I didn't mean to imply that, but with all the movies about this stuff I guess I shouldn't be surprised that's what people assume. Breaking it into pieces without altering its trajectory would basically be turning a bullet to the face into a shotgun blast to the face. You could argue about which one is worse, but both are still really bad.

No, you'd use the nuke to try and deflect the rock instead. The bomb would go off a few hundred to a few thousand meters off to the side, and the its radiation flash, what there is of its shockwave (not much of one in space), and outgassing from the momentarily super-heated rock from its surface would 'nudge' it into a new trajectory. For most earth-crossing asteroids, one or two nudges should be sufficient, given how big space is even a week or two out form Earth.

I recall all this because I wrote a pretty extensive article on redirecting asteroids for my website a while ago. If you want to read more, the link is:

http://orbitalvector.com/Solar%20Sy.....0ASTEROIDS.htm

If the asteroid is broken up outside the atmosphere, the smaller asteroids will more than likely burn up on entry, causing a pretty but otherwise harmless series of brilliant shooting stars. More surface area to burn away at, and all that. You'd want to make sure that the nuke lands well before the atmosphere, though, so it can protect the planet from the radiation from the nuke. Even if you do get some meteor strikes, they will be of the order of a dime landing from the top of the empire state building, rather than the order of "The Moon Is A Harsh Mistress".

And missing someone by a few feet at a range of a half-mile? Pssshh, with civilian-grade hunting rifles, I've got a +90% accuracy on two-inch targets at about that range (I use one kilometer, which is roughly a half mile). Someone that misses by that much either doesn't have much practice with firearms, or sneezed just as he was pulling the trigger.

Breaking up an asteroid wouldn't work out quite that simply. We're talking about mountain-sized or better chunks of rock--many millions, perhaps billions of tons of mass.

There's more too. Something just falling out of orbit will hit the atmosphere at seven miles per second--25,000 mph. Asteroids, coming in at their own trajectories from deep space, will be moving significantly faster than that. in relation to Earth. So you have a billion ton mountain flying at you ten times faster than the fastest bullet.

Remember the basic formula for force; F (force) = m (mass) x a (acceleration). If you break an asteroid apart into a million bits with a nuke, you aren't altering its mass at all. You also aren't slowing it down at all--its would take far more energy to slow down a billion tons worth of rock to 'safe' speed than it would to just blow it apart. Think of hitting a jet aircraft with a missile, I'm sure you've seen footage of that. The mass of the airplane doesn't just stops dead, it keeps going straight ahead, just now in thousands of pieces of shrapnel, following the same trajectory the jet had before, and only changing when gravity take hold.

So by blowing it apart, you aren't really changing any parameters of the equation. Earth still gets hit by the same amount of force whether its all in one chuck or blown apart into a million shards.

So let's say instead of a single million ton rock heading your way at Mach 25+, you have a million 1-ton rocks doing the same, all at once. They might be small enough to break up in the atmosphere, but the problem is all that energy still has to go somewhere.

One thing most people never really think about is that the Tunguska Event was an airburst--the comet exploded about 10 kilometers in the air above the ground (my statement of 40 Mt for the event was erroneous--estimates I just read now put it at between 10 and 15 Mt. Apologies). And it was still powerful enough to devastate an area of over 2000 square kilometers and induce a seismic event estimated at 5.0 magnitude.

Only now you're spreading this damage out over a much wider area. Instead of it just hitting one area, and decimating that, you may spread the damage over an entire continent. But all the disintegrating rocks combined still produce massive shockwaves both on the ground below them and laterally, and there's thousands or milliosn of them doing it in relative close proximity within several seconds of each other. Remember that though they may be (relatively) small, they'r still hitting the atmosphere at ungodly speeds, plus there's a million of them. In accumulated effect, they'd superheat the air and cause anything combustible in the affected area to catch fire--for thousands upon thousands of square kilometers, in addition to anything smashed to bits by the initial shockwaves. That's just on land. if it happens over the water you have the potential for tsunamies caused by the accumulated shockwaves and superstorms formed by the superheated air and water.

Like I said, its bullet vs shotgun blast. Which one is worse? No one really knows, and no one is anxious to find out. Which is why scientists always talk about deflecting an incoming asteroid, not blowing it up.

A dime dropped from the Empire State Building would cause almost no damage at all. You might get a small bruise if it hit you in the noggin. Terminal velocity slows it down too much.

And the bullet-head thing was just a hasty metaphor, one I admit was probably flawed.

Only we're talking a significant difference in location.

You're talking 10Km up. I'm talking lunar orbit. That way, it has to get all the way through the atmosphere first. Broken up. Your first nuke fractures it. Successive missiles pound larger chunks until you deal with manageable half-tone or smaller sized chunks left which WILL completely disintegrate into the atmosphere.

Remember, once it hits atmosphere, the air friction starts working against it, as each piece individually burns up, rather than the outermost pieces protecting the inner ones.

I'm well aware of F=MA. No, I'm not altering the mass of the asteroid by the detonation (other than those lighter elements which are destroyed in the heat of the impact, which won't account for very much). I'm breaking it up into millions of little pieces, but the absolute mass is practically identical. However, each of those individual pieces interact separately with the atmosphere and air friction, so that by the time they get down to sea level, they will have abraded almost completely away.

In fact, the abrasion from the atmosphere actually *aids* in this, as now they have little particles that are acting as sandpaper. For each force, there is an equal force applied in the opposite direction, now the remainder of the asteroid strike is being crammed through a sandblaster at that same Mach 25+... shredding itself. It's almost literally like watching a stick of butter being pushed against a hot skillet. The first bits which are disintegrated actually aid in destroying the rest of it as it comes in piecemeal.

Furthermore, multiple nuclear detonations will alter it's trajectory significantly, as listed in the journal you posted. Multiple direct hits on the same location will begin to scatter the asteroid bits which break off over several kilometers, rather than a focused single point, which increases the surface area to abrade against by several orders of magnitude, allowing the friction and abrasion from airborne particles to work much more effectively.

Yes, if a single asteroid of that size were to impact, it would cause serious devastation. However, shattering it while it is still out in a Lunar Orbit distance will reduce the danger by a factor equal to the number of pieces it breaks into. Granted that if it waits until it is already in atmosphere to break apart, then the damage will still be done, because it won't have the time to fully take advantage before it hits, causing roughly the same damage, although spread out in a larger area, with an impact crater significantly differently shaped (not as deep, but wider). But striking it while it is still outside lunar orbit and causing the damage well before it gets into low orbit will be able to break it up into pieces which will not be able to survive reentry (should we call it reentry, since it never entered in the first place?) to sea level, due to the effects of the atmosphere.

Ah, deflection, yes, I see. I figured trying to blow it up would be a bad idea. And even if doing so makes particles burn in the atmosphere more easily, it's still a hell of a lot of energy that has to go somewhere.

Thanks, interesting read.

When in doubt call Bruce Willis

For a moment, I thought you were talking about the two asteroids that are co-orbital with the Earth and Moon and would be small moons if they orbited us rather than simply being co-orbital. o:

That said, rocks are always flying around us. I blame Jupiter.