In the movies, the Americans stop the asteroids. As of this week that responsibility falls to the UN (sort of).
As a result of a vote by the General Assembly last week, the International Asteroid Warning Group will be conjured into existence as a place for countries around the world to share information about dangerous asteroids. Here’s Clara Moskowitz in Scientific American:
If astronomers detect an asteroid that poses a threat to Earth, the UN’s Committee on the Peaceful Uses of Outer Space will help coordinate a mission to launch a spacecraftto slam into the object and deflect it from its collision course.
[Former astronaut Ed] Lu and other members of the Association of Space Explorers (ASE) recommended these steps to the UN as a first step to address at the long-neglected problem of errant space rocks. “No government in the world today has explicitly assigned the responsibility for planetary protection to any of its agencies,” ASE member Rusty Schweickart, who flew on the Apollo 9 mission in 1969, said Friday at the American Museum of Natural History. “NASA does not have an explicit responsibility to deflect an asteroid, nor does any other space agency.” The ASE advocates that each nation delegate responsibility for dealing with a potential asteroid impact to an internal agency - before the event is upon us.
The Committee on the Peaceful Uses of Outer Space referred to above is a body that’s been around since 1959. It’s something of a relic of the Cold War, as it was set up in the aftermath of the Sputnik launch in 1958, and it will fall to this committee to coordinate our global space defence if an asteroid comes our way.
Something to consider here is that we don’t have a proven method of stopping an asteroid, so coordinating research into that kind of technology might be one of the committee’s first tasks. Possible methods proposed by scientists include explosions (obviously), deflection with a large object, ion beams, powerful lasers, and even converting it into a kind of rocky spaceship by attaching spaceship engines to it.
Even if governments aren’t totally on the ball when it comes to spotting asteroids, however, there are private organisations that are also watching the skies. Ed Lu (mentioned above) has flown on the space shuttle and carried out a mission aboard the International Space Station, and was one of those who recommended the creation of the International Asteroid Warning Group to the UN. He’s also the founder of the B612 Foundation, which is planning on launching its own asteroid-seeking space telescope (Sentinel) in 2017. B612, by the way, is the name of the asteroid that Antoine de Saint-Exupéry’s Little Prince lives on.
Scientific American quotes Lu as claiming that there are a hundred times more asteroids “out there” than we’ve found so far. Is that true? Probably.
According to Nasa, we’ve found 95 percent of asteroids that pose a danger to Earth that are bigger than 1km in diameter. That’s good - those are the ones that would cause mass extinctions (including our own). But we also know that it doesn’t take even a tenth of that to cause widespread destruction. The asteroid that caused the Tunguska event is estimated to have been at least 60m wide, while the Chelyabinsk meteor was probably no larger than 20 metres and injured nearly 2,000 people.
Nasa thinks that there are probably around 19,000 asteroids between 100 metres and 1km in size that post a risk to Earth, and millions more that are smaller even than that. We’ll be able to deflect asteroids (hopefully) if we have enough warning that they’re coming, and we’ll spot them further in advance the bigger they are. And while a civilisation-killing piece of deadly space rock isn’t quite as dramatic, the random chances of death from above on a smaller town, city, or village-like scale is still a rather worrying prospect.