Even If We Can Stop a Dangerous Asteroid, Being Human May Mean We Don't Succeed

To err is human, and that saying doesn't magically become moot just because the stakes are high.

That was the message political and legal experts offered to scientists gathered at the International Academy of Astronautics' Planetary Defense Conference, held in College Park, Maryland, last week. The conference was dedicated to discussing planetary defense — the art of spotting and, if necessary, diverting asteroids that seem to be on track to hit Earth — from a range of perspectives, bringing together asteroid scientists, spacecraft engineers, disaster managers and, yes, political and legal experts.

Scientists and engineers know in theory what they could do if an asteroid threatens serious damage to any patch of Earth, depending on how much warning they have. They can send one or more large spacecraft up to block the asteroid's path and slow it enough that it misses its date with Earth. Or they can detonate a nuclear weapon near the asteroid's surface, vaporizing some of the rock and sending the remainder of the body in the opposite direction.

Related: A Fake Asteroid Headed to Earth Can Really Make You Think 

And assuming that they can get good-enough observations of the asteroid, they can do all the math to figure out when to knock it, with how much force, carried on which rockets, launching on what date. What could go wrong? A lot, it turns out!

Some of that room for error comes from the simple nature of spaceflight. In a scenario that conference attendees played out with a fictional asteroid, humanity launched six spacecraft to slow the asteroid down — and then things went wrong: three spacecraft failed to reach the space rock and one broke it into pieces, the smaller of which was still on track to hit Earth. 

The intervention saved the original at-risk city of Denver, but simply moved the disaster irrevocably to New York City. (Again, this was a hypothetical scenario. Scientists don't know of any large asteroids — more than 460 feet (140 meters) across — that could hit Earth in the foreseeable future.)

But spacecraft missions not always going according to plan is nothing new. What several of the speakers highlighted instead were the societal factors that could stymie or complicate any attempts to divert an asteroid.

First comes the question of who should be able to decide whether to try to divert an asteroid at all. The experts speaking at the conference were vehement that such a decision shouldn't be the purview of just one country.

"Just the prospect of having one country saving the whole world obviously carries a lot of geopolitical concerns, a lot of concerns of power," Petr Bohacek of Charles University in Prague, Czech Republic, said during a presentation. "As we know from many experiences in the past, good intentions themselves, they are not sources of legitimacy, they are not free of power, they are not free of national interests."

Related: This Scientist Is Creating Fictional Asteroids to Save Humanity from Armageddon

But there is no international body that fairly incorporates all the countries that could potentially be affected, Bohacek and others emphasized — even in the United Nations. The U.N. General Assembly can't make binding decisions and gives each country the same voice regardless of their population or risk. The U.N. Security Council includes only 15 countries and can be swayed by the five permanent members with veto power, and the U.N. Committee on the Peaceful Uses of Outer Space only includes spacefaring countries.

Let's assume that conundrum was ironed out — perhaps, as Cordula Steinkogler of the University of Vienna suggested, by creating far in advance an internationally agreed-upon procedure for handling planetary defense decisions. Steinkogler is a member of a legal committee assembled by the Space Mission Planning Advisory Group, an international group of experts focused on planetary defense.

The next challenge would be determining which country or countries will attempt the deflection, presumably from among the spacefaring nations at the time, whether or not those overlap at all with the countries at risk of impact. But because of the way legal regulations and international agreements are currently worded, presenters noted, those countries would have plenty of motivation to leave an asteroid alone.

Steinkogler noted that there are no legal obligations explicitly requiring any country to inform people about a hazardous asteroid or to take action about it. There are only general statements about a country's obligation to protect human life within its borders, she added.

And there are clauses that may discourage a country from taking action against an asteroid, even if it is predicted to crash within the same country's borders, David Koplow of Georgetown University Law Center, said during his presentation. In particular, the key risk here would come if the action not only failed to deflect the asteroid from hitting Earth, but moved the impact site into another country's territory. At that point, the country or countries behind the mission could have to pay the affected country for the asteroid's damage.

"If the harm occurs on the surface of the Earth … you are required to pay compensation, even if you have done nothing wrong, even if you've behaved according to the highest standards of technical capability," Koplow said. "Nonetheless, the concept is that space activities are hazardous or ultrahazardous, and therefore the harm should not fall on an innocent bystander if damage is inflicted on the surface of the Earth; the country responsible for doing that activity is liable, even if they've not behaved in any negligent or wrongful fashion."

But even if the world comes to an agreement here, too, there's one more knotty issue flagged by the legal and political experts. That comes from one of the tools that humanity could use to deflect an asteroid, nuclear explosive devices. Steinkogler said that the committee she was part of concluded that language within the Outer Space Treaty, a key treaty that has governed space exploration for decades, bans all use of nuclear devices, even those that aren't intended as weapons.

Even just talking about nuclear devices as a potential technique for averting an asteroid has international consequences, according to the presenters, since it could convey the impression that nuclear devices are a critical resource to protect citizens. That could easily undermine the principles of non-proliferation, which presume that non-nuclear countries can trust their safety without such devices.

All three of these problems — as so many facets of other global-scale threats — are complicated because there is no global process that is independent of individual countries. "[When it comes to] deciding about global issues, we do not have much of a good track record, whether it's climate change, whether it's other problems," Bohacek said. "The main concept upon which the international system is based is state sovereignty, and that's a concept from the 17th century.

"I'm not sure how many concepts from the 17th century you are using for your work, but making political decisions about planetary defense on this dinosaur form of decision-making might not be the best way to deal with that."

• Humanity Will Slam a Spacecraft into an Asteroid in a Few Years to Help Save Us All
• Photos: Asteroids in Deep Space
• Wow! Asteroid Ryugu's Rubbly Surface Pops in Best-Ever Photo

Email Meghan Bartels at mbartels@space.com or follow her @meghanbartels. Follow us on Twitter @Spacedotcom and on Facebook.