The Tunguska discussion got me curious. Does anybody know if the President of the USA has the authority to direct that nuclear weapons be launched to either destroy--or more likely deflect--an oncoming asteroid or comet? I want to stress that I'm not interested in anyone's opinion of President Bush, Senators Clinton or PHRASECENSOREDPOSTERSHOULDKNOWBETTER., Al Gore, John Kerry, or Fred Thompson, so let's keep the politics out of it. Rather, I'm interested in a purely theoretical discussion of what exactly would have to happen before such a launch took place. Here are some points to ponder:

1. Would the President need the consent of Congress to launch? (I don't think so.)
2. If not, would he need their approval for the funding? (Probably.)
3. Should the U.N. be consulted? (Remember, no politics. I know, I know, this one might be hard.)
4. Are such plans already in place? (IMO, if not they oughta be.)

I'm aware that there are other ideas being considered for "planetary defense" but they are years away. Nukes are available now. Thoughts?

My gut thoughts:
1. Consent of congress: Need? No. Get? Yes.
2. Funding: Yes
3. UN: I'm not going there.
4. Current plans: Probably, though mopping up after the impact is probably a bigger folder.


Questions of my own:

1. Can the current crop of nuclear missles escape Earth's gravity or are they limited to ballistic paths only?

2. If need be, could several missles be launched from the space shuttle? (wouldn't THAT cause an uproar!)

3. Would the missiles' navigational systems be able to direct them to an asteroid?

4. What would happen if a missle sucessfully hit the asteroid but something still impacted the Earth? (more uproar/conspiresy theories)

5. How would we convince Russia/China/etc that the missles were actually heading towards some object in space?

-Blast

I would imagine that there is nothing really that we could do...

Missiles are not designed to leave Earth's gravity well. That would certainly drive up the cost, and there were never any Russians on the moon, so there was never the need. Missle engines are not big enough, and I am pretty sure that the guidance systems are not up to snuff to hit a moving target in space, even if the engines had enough horsepower.

It certainly is possible to make an "asteroid killer" missle (and there would certainly be an upper-limit on the size of target that could be disposed of), but that would require a rather large source of funding, which would seem to kill the idea instantly for something that is likely to be needed once every few million years or so.

Agreed.

1. Nope, they are suborbital.
2. Given a few years to work things you, perhaps.
3. Nope, they are designed to target a geographic location, not something zipping in from interplanetary space.
4. Dunno
5. If they can "see" them, they can see where they are headed, I guess...

My opinion:

1) No, in fact it would probably be better to inform them after the fact, it's better to beg for forgiveness than to ask for permission when it comes to Congress.

2) Doubtful, the government has been funding the research and development of "black ops" for years and concealing the funding by inflating other aspects of the budget. For example, they could simply increase NASA's budget without specifying the exact project to be funded.

3) No because the UN would finally come to a decision to take action 30 seconds AFTER impact.

4) Yes, FEMA developed the plan, the details of which are being guarded by TSA employees and the whole thing falls under the Department of Homeland Security for execution.

I think that one of the main things to take into consideration when deciding on a delivery vehicle for the warhead would be that the object would need to be taken care of a lot farther away from earth than Hollywierd would have you believe. A hit weeks/months before the object were to collide with the Earth would be needed to deflect it sufficiently. What do we have READY to make this long of a journey?

Due to the fact that the nuclear detonation would be in a near vacuum, I believe that the device would have to be detonated in contact with the object to have sufficient effect too. Do we have a guidance system READY that would provide the terminal guidance for this? The ABM guidance system?

In response to norad45
1. the president does not need permision to release nuclear weapon(but will be raked ove the coals after)
2. Funding is already built into the budget to launch nukes and other spacecraft.
3. I'm with Blast here.
4. I dont know, with the way people work anymore probably not.
In response to blast
1. Our balistic missiles can escape orbit but in the normal course of things do not because their normal target is not in space but here on earth.
2. Dont know if they have the system in place but it wouldn't be hard to place a launcher from a sub in a shuttle (shouldn't take to much modifications)
3. They could direct it from the ground.
4. TSWHTF!
5. Have know idea?!

Wasn't there a Nat. Geo special that pretty much dispelled the idea of using a nuke to intercept an asteriod? I believe they said it would either be totally ineffective or at best could potentially make the situation much worse by fragmenting the asteroid.

re, #4.

Odds are, something will impact. We have no way of predicting what the shot pattern would be. It's all very heroic and macho to talk about nuking something, but you'd have better control with a relative small kinetic impactor or a motor that makes a softish landing nudging the entire thing out of the way.

It's one thing to catch a bullet with your teeth. It is a completely different one to catch a load of buckshot with your teeth.

If an asteroid was heading in this direction, there should be considerable warning ahead of time.

If a rocket could be sent to knock it off course enough while its far enough out, wouldn't that deflect it enough? Embed the rocket nose, then activate the jets? Just one degree off on your compass in a 50-mile trek would put you way off your target.

Not that I know what I'm talking about. I guess reading all Robert Heinlein's books isn't enough...

Sue

Depends on the size of the fragments. If they are small enough, they should burn up before impact.

Bingo- simple, easy, and it works. Apparently half of NASA and the USAF haven't, or ignored Newtonian physics in high school. :P

I like the "should".

Oh, and where does the particulate debris go when it "burns up"? To Earth. Ok, you've made a rock the size of Denali into a swarm of pea stone. At best, someone is getting a silicon snowfall. :P

Yes, there was a pretty good science show on that went over the options pretty well, concluding that just trying to blow the thing up or off path probably wouldn't work, and would tend to make the situation worse. The general consensus is to try and steer the projectile out of collision path using a propulsion system that wasn't too abrupt so as not to create acute stress levels that might cause structural failure and fragment the object. That of course assumes we detect in with sufficient time to deploy such a system and the thrust applied long enough to clear the object out of path.

Nukes might disintegrate the smaller objects capable of surviving the atmosphere, but then you would have nuclear fallout raining down with the debris stream. The planet killer sized asteroids cannot be destroyed by nuclear munitions currently developed and capable of being deployed in such a manner. Regardless, we don't have anything that could deliver a nuke payload effectively as an interceptor, though the technology is there to build one if we wanted to. My guess is it will be another hundred or so years before we could begin deploying an effective global defense system that would fairly eliminate the possibility of a strike.

What's interesting is that only in the last 40 years have we had sufficient technological development to be able to even contemplate such a task. It is a race; to see whether we can develop quick enough to prevent our own demise, while also avoiding being the cause of it. At no other point in time has there been a species capable of changing their own fate so. It is amazing that we might actually pull it off in the span of one lifetime.

Sometimes I think we may actually learn how to live forever. Imagine how far science has come in the last 200 years, and how far it will advance in the next 1,000. Most Science fiction really only deals with future in the near term, but what about a millenium from now, assuming nothing disastrous were to happen in that span. If our technology were allowed to continue developing contiguously for that long, what limits that we know of today can be overcome? In time, I believe anything and everything is possible.

Completely agree with you on this. If identified early enough in the process, a small nudge when it's halfway across the solar system will deflect it away from the earth. Unless Bruce Willis and his rocket team isn't available to destroy it just before it hits the earth's atmosphere (I know, bad movie, but strangely entertaining. )

Honestly, if this event would happen in the next decade, I think we'd be better off making peace with the respective deity of our choice rather than planning to survive the impact. This type of event falls into my "Very Low Probability, Devastating effects, worldwide change, little that I can do about it" category.

Someone is working on planetary defense. And its not by using nukes. This article is a little dated, but I do see news items from time to time that indicate the group is still around and doing work.

http://www.voanews.com/english/archive/2...FTOKEN=61465346

According to a Discovery Channel program I saw 2+ years ago, as of 2001 the estimates were that we had only discovered a small percentage of the NEOs (near earth objects), and that current programs would take several decades to find and map them all. The upshot of that program was that without a lot more telescopes directed skyward searching for these things, we might only get a few days' warning - certainly not enough time to develop the technology to deflect or stop something.

The impact of Shoemaker-Levy on Jupiter proved it can and almost certainly will happen. The open question is when.


Frank2135

The general concensus seems to be that the President has the authority but that he would still need to turn to Congress for the funding. (I seem to recall a treaty that prohibits nukes in space. I doubt it would provide much of a constraint given the situation, but it might make testing problematic.) I don't believe for a minute a "black ops" account exists that is large enough to fund a project as huge as this.

The unsuitability of ballistic missiles to deliver the warheads is a good point. Am I wrong in assuming that NASA has and would use another type of rocket?

Some of the responses seem to suggest that trying to deflect an object with a nuclear weapon would be futile. But wouldn't that really depend on the size of the rock, the size and/or number of the nukes (after all, we've got thousands of 'em), the composition, and, maybe most importantly, the distance to intercept?

I think it makes sense to be prepared to do what we can do. It would be a shame if we were not ready to give a nuclear nudge to a 1/4 km wide comet that comes along because we got hung up trying to figure out the best way to shove a 5 km wide iron-core asteroid that isn't. By all means we should develop other methods but until then we should think about how best to use the tools we have.

And we definately need to get an early-warning system in place.

The big issue is not stopping the asteroid, its seeing in time to intercept it.
OK, a few facts:

1) TEOTWAWKI dinosaur killers (T-object) are not the main threat. They are easy to spot and deal with.
2) The real threat is nickle iron asteroids of 50 to 100m diameter. They are too small to see at any real distance and big enough to survive entry into the Earth's atmosphere. If one of them landed on a city it's goodbye London, Washington, New York etc.
3) The most powerful earth based radar has a maximum range of about 1 million miles (about 6 light seconds). It can only see asteroids of the size given above at about 1 1/2 light seconds.
1.5 L/sec is about the distance of the moon.

That means that you have less than a day at the sort of velocity's normally associated with interplanetary objects to spot it, calculate it's trajectory, launch and intercept it. You also have to "kill" it far enough away so as to prevent the E.M.P. pulse (Electromagnetic Pulse) for destroying ground based electronics. You also have the problem of fusing the Nuclear Demolition Device (sorry, sounds better than warhead)so as to ensure that the fireball reaches it's optimum diameter just as the asteroid reaches the same point. Too early and the fireball may be too diffuse. Too late and the asteriod may impact the N.D.D. before it can fuse. The differance may be as little (depending on the size of the yield)as a couple of milliseconds.

Also, contrary to received wisdom a T-object will cause far more harm intact than the same object would as fragments. If it has been shattered, a lot of it's mass will burn up on entry into the atmosphere. Despite Hollywood's love of drama, you would not launch only one device. You would launch as many as you possibly can. Sequence would be: Shoot, Look, Shoot. As needed. You also have the option of using the follow up shots to vapourise the remaining fragments.

We already have the means to deal with T-objects that are detected at interplanetary distances. All you need is accurate information with regards to it's trajectory and a fairly simple interceptor vehicle of the type used recently in NASA's asteriod impact mission. That would consist of a high impulse ion engine. As much fuel as possible and a depleted uranium rod, ball or bar on the front end. Idea is to hit the T-object at as high a velocity as possible. Mass x Velocity = Apparent Mass. In other words the faster it hit's, the harder it hits. Slows the T-object down by a few mm/sec. That is more than sufficent to generate a miss.

Agreed.



I'm not sure there is consensus on this.


Frank2135

I think that the biggest threat would be from the more likely impact site, the ocean. Even a small, dense object traveling at these speeds hitting the ocean could take out more cities than just one. Could take out entire contries if it hit the right spot.

We definately need a new system to detect the smaller rocks further out. I remember in the aftermath of Shoemaker-Levy there was much talk about building one, but as always when the images were no longer dominating the TV the talk died down. I hope the next wake-up call, when it comes, isn't too nasty.

Perhaps, perhaps not, it would weigh in at something around 500,000 to 1,000,000 tonnes. Depending on the impact velocity, you are talking a couple of megatons. A T-object is in the Gigaton or Tetraton range. A tsunami might result from a small object impacting off a coastal city but it wouldn't be widespread. Not enough energy involved.

A T-object however......
Thats bend over and kiss your...... goodbye/global extinction event time. For the whole planet.