Forget YouTube; for one night and day we let’s pay attention to YU55.
Tonight, this “potentially harmful” asteroid will whiz within a whisker of the Earth – a mere 200,000 miles distant – at a speed of some 30,000 mph. The asteroid is some 400 m in diameter. For scale, NOAA readers of this blog might think of this object as having a diameter slightly greater than the length of the Herbert C. Hoover Building – the Department of Commerce headquarters, occupying an entire city block of downtown Washington, DC. As for that speed? It’s 30 times the muzzle velocity of a Glock 9mm.
2005 YU55 has its own Wikipedia entry. But it is just one of thousands of so-called Near-Earth objects which have been identified and are being tracked by NASA’s Near-Earth Object (NEO) Program. And that designation “potentially harmful?” It’s NASA-speak for the class of asteroids whose orbit and size (one kilometer, a little more than twice the size of YU55) pose a threat of collision with the Earth.
Suppose an asteroid that size were to strike? Just how bad would it be? For comparison, scientists estimate that the asteroid which struck Tunguska in Siberia in 1908 was maybe only 40-80 meters across, but that the explosion was maybe the equivalent of 10 megatons of TNT, about the energy released in the first hydrogen bomb test. That asteroid didn’t actually hit the Earth. Instead it exploded a few miles above the Earth’s surface, flattening the trees over a 1000 square mile area (ten times the area of Washington DC proper). [A tenth the size? But maybe 1/1000th the mass, and therefore 1/1000th the energy.] And that K-T meteor we might have to thank for getting rid of those pesky dinosaurs 65 million years ago and giving mammals a fighting chance? Maybe only 10-20 times larger in size — and 1000 times the energy.
NASA estimates that there are maybe 2000 objects in this class – and they’ve found more than 90% of them. As for that remaining 10%?
Let’s just say we wish NASA every success with their NEO program. At $5M/year. It seems like a bargain. And so do those programs developing the technological means to change the course or destroy asteroids that may some day pose a threat to mankind’s existence.
Of course those are government programs…and discretionary spending at that.