NASA's Fireball Program Will Test if Asteroids Hit Earth as Randomly as We Think
We have no clear idea of whether or not any one place is more likely to get hit with extraterrestrial debris.
If it weren’t for NASA’s automated Fireball and Bolide Reports system, no one would have ever known about the asteroid. The rock in question broke the surface of the Atlantic Ocean in February after piercing the atmosphere with the force of 13,000 tons of TNT. It was traveling thousands of miles an hour. Had it hit a city, no one would have seen it coming.
If you give an astronomer an asteroid’s size, its angular velocity, and composition, he or she could give you a decent approximation of what would happen when the asteroid hits. Less clear is predicting where on earth impacts are most likely to occur. But there’s a good chance it’s wet. “Just over 70 percent of Earth’s surface is ocean, which means about 70 percent of the impactors will land in water,” says William Cooke, a small-object expert with the Meteoroid Environment Office at NASA’s Marshall Space Flight Center in Alabama.
This is true.
As a species that wants to survive for another couple hundred thousand years, we’ve become increasingly invested in tracking the asteroids in our solar system. Not because the frozen chunks of rock are particularly interesting on their own, but because they have the potential to become either meteors (the bright fireball flashes in the sky) or meteorites (the hunk of space rock that lands on Earth). If those are big enough, of course, they become extinction-level events. NASA keeps an eye on larger asteroids in the solar system, like the “big-ass meteor” that zipped by Monday morning. But where an object is likely to land is a bit of an astronomic crapshoot.
As far as we know, impact events aren’t more likely to land at, say, the equator than a pole. “No pattern discernible, as you can see from this plot released by NASA in November of 2014,” Cooke says. “Looks pretty random.”
Compounding the problem is that meteoric events, if they occur in isolated areas, go unreported. There are a few ways to spot meteors without human eyes or sensors, like seismometers, infrasound arrays, and satellite cameras. Cooke needs compound eyes to keep watch on the whole planet. But that’s just to get data, not to wring out a conclusion about when asteroids wind up hitting water or rock. There is simply no way to know that yet.
“We are just now beginning to establish networks that don’t rely on human feedback to extract information about fireballs,” Cooke says — NASA’s fireball program relies on cameras to spot unusually bright spots around the globe, for instance — “and the coverage is nowhere near what we need.”
When the program is up and running, data collection will improve significantly and we’ll be able to install “Beware of Falling Rocks” signs at appropriate locations.
