On Volokh, the possibility of ‘AsteroidGate’ is discussed. Although the asteroid 2004 MN4 was originally suggested to have a 1 in 300 chance of hitting earth in 2029 (why worry? Everyone knows the earth is going to be destroyed long before then in 2012), it appears now that the true risk is closer to 1 in 250,000. I’m pretty comfortable with those odds myself — and even Dick Cheney’s one percent doctrine is clearly uncalled for, at least in the case of 2004 MN4.

However, a Wired article linked to on Volokh, Saving Earth From an Asteroid Will Take Diplomats, Not Heroes, brought up a few key points on why international law will have a big role to play in saving the world, should a big chunk of space debris ever head our way.

In the movie Armageddon, nuclear warheads are placed on an incoming asteroid to make it explode and miss earth. In real life, this never would have happened — nukes in space are clearly a violation of international law, and there is no “eminent extinction” exception provided for. In addition to the prohibitions contained in the Nuclear Test Ban Treaty, there is Article VI of the Space Treaty, which provides that:

States Parties to the Treaty undertake not to place in orbit around the Earth any objects carrying nuclear weapons or any other kinds of weapons of mass destruction, install such weapons on celestial bodies, or station such weapons in outer space in any other manner.

As AsteroidGate illustrates, it would be naive to assume that something as insignificant as the human race reenacting the dinosaurs’ extinction would be enough to cause mankind to join together to defeat a common threat. If, tomorrow, an asteroid were discovered that was a couple years away from impacting earth, I imagine the conversation would go something like this:

United States: Hey, UN, there’s this asteroid headed towards earth. Just to be on the safe side, we’re sending some nukes up into space to blast it to smithereens.
Rest of the World: Like hell you are. Do you really think we’re dumb enough to fall for the old “we’re all going to die if the U.S. doesn’t get to use nukes” routine again?
U.S.: No guys, I’m for serious. Here, check our facts. There is .2% chance that the earth will utterly perish in world ending explosion, and a 3% chance that it will only give us a glancing blow, only causing 75% of the human population to die off.
Rest of the World: You just made these numbers up. Let me guess, these figures come from the same research agency that found WMDs in Iraq? And besides, even if you didn’t make them up, our 3% odds with the asteroid are way better than the odds the earth would have once countries started launching nukes into orbit.
China: I think the U.S.’s idea sounds great! We’ve got some nukes we’ll send into space to help too, everyone cool with that?
U.S.: Oh, hmm, well this is a little bit awkward. Listen, China, thanks so much for the offer, but we were kind of thinking we’d be the only ones sending up nukes to kill the asteroid. You know what? Why don’t you just sit back and relax. Out of our deep feelings of generosity towards the UN, the United States will volunteer to cover all of the expenses of the Nukes-In-Space program.

In short, if an asteroid was discovered a few years away from hurtling into the earth, it’s a close call about which happen first, the international community deciding who and how would get to send up nuclear weapons, or the asteroid finally hitting us.

Nuclear weapons are not the only theoretical way to avert an asteroid impact, but there is no option that will not require extensive international coordination to implement. The B612 Foundation, for instance, proposes a long-term slow diversion of the asteroid:

Our preferred solution to deflecting an incoming near Earth asteroid (NEA), for reasons that are clarified below, is to rendezvous and “dock” with it at either its North or South Pole, realign the asteroid’s spin vector to a preferred direction and then push it (gently and for a long time) until we’ve changed its speed enough to miss the Earth.

But, as the Wired article above points out, this causes its own set of problems:

That’s a major geopolitical problem, Schweickart said, because it requires temporarily increasing the risk to one population — in the example above, Venezuela, or Russia — to eventually eliminate the risk for the entire Earth.

“It’s going to be slowly dragged across the Earth. That is a binary decision,” Schweickart said. “You don’t have the option of dragging it down through the Antarctic.”

Who gets to decide which way the asteroid is dragged away from an impact with Earth? The United Nations? The United States? Russia? Some independent body of astronomers and space agencies?

“What deflection technologies are OK and who says they are OK?” Schweickart asked. “Who accepts liability? How do you decide that it’s OK to endanger the people of Venezuela or the people of Kazakhstan?”

True, Siberia is in many ways an ideal place to risk an asteroid impact — they got hit by one last century, and it took a couple decades before anyone even noticed — but I do not expect that Russia would be too amiable to the suggestion. I suppose you could attempt some sort of economic solution, i.e., the countries that accept a small increased risk of being asteroided will not have to contribute to the cost of the asteroid diversion program, or maybe even receive payments from the countries not put at risk. Of course, this might very well be held up as an example of the developed countries, once again, putting the developing nations at risk to save their own hides.

-Susan