Respected scientist-astronauts have been saying it for years: We need to prepare. But before the UN General Assembly approved new measures this month, no country had even been on the lookout for asteroids that might be on course to hit earth, Scientific American reports. As one Apollo astronaut, Rusty Schweickart, put it: "If we don't find it until a year out, make yourself a nice cocktail and go out and watch."
Planetary protection apparently isn't just a job for Bruce Willis. The threat is real. And, actually, "deep impact" has happened before.
In 1908, a meteorite exploded over a place called Tunguska in a remote part of Siberia. For decades no one was quite sure what flattened trees for miles around but caused no crater. Scientists later discovered the rock fell so fast (around 33,500 mph) and got so hot (44,500 degrees Fahrenheit) that it simply exploded several miles above the earth with the force of hundreds of atomic bombs.
Then in 1994, the same kind of thing happened again, only this time to our distant neighbor, Jupiter. A comet called Shoemaker-Levy 9 splashed into the planet's gaseous surface, leaving bright scars visible from earth.
And just this February, Russia got splattered again with space debris when meteorite bits rained down on Chelyabinsk, injuring more than 1,000. Divers found a 1,300-pound fragment at the bottom of a lake.
"We are literally living in a cosmic shooting gallery," the group B612 says on its website. It adds: "The probability of a 100 Megaton impact somewhere on earth each and every year is the same as the probability of an individual being killed in an automobile accident each year — about .01 percent."
B612 has been urging space agencies and the UN to develop some kind of plan to both observe an impending collision and divert it far enough in advance that we don't have to worry. A rock of just average size could wipe out a city.
On Friday, scientists from the Association of Space Explorers gave a talk at the American Museum of Natural History in New York City. "There are 100 times more asteroids out there than we have found. There are about 1 million asteroids large enough to destroy New York City or larger. Our challenge is to find these asteroids first before they find us," NASA astronaut Ed Lu, CEO of B612, told Scientific American.
Once we find one, there are a few options for what to do about it. The UN seems to be running on the general plan to fly something big into the asteroid years before it would reach us. A slight change in tragectory would send it off the collision course.
Another option: asteroid cannon. The Japanese space agency, JAXA, is doing reseach on asteroid composition and launching a space gun to fire a big metal bullet into a nearby asteroid.