Last week's close approach of Asteroid 2007 TU24 had many people concerned. This was all for naught, however, as astronomers knew that it would not impact the Earth. Still, the internet was chock full of sensationalized videos of people being genuinely scared of this asteroid. On the other end of the spectrum (the logical end, I might add) was Phil Plait, of Bad Astronomy. His video settled it once and for all. So its obvious that Asteroid 2007 TU24 posed no danger to us. But what if it had? Now that the asteroid has passed, we can look back and think: "What did we learn?"
So what exactly did we learn? We should take this opportunity to think about the possible scenarios. The first scenario, which is what actually happened, is that the asteroid completely missed us by a long shot. This is easy to deal with; just enjoy the show it puts on as it zips by. But what if the asteroid had been on a collision course with Earth? What would we have done?
If Asteroid 2007 TU24 had been on a collision course, there would most likely not have been anything we could do. With size estimates ranging from 150 meters to 600 meters, the asteroid would most likely have impacted the surface. Although it pales greatly in comparison to the "dinosaur-killer", which was about 10 to 20 kilometers across, this asteroid could have done some real damage. This damage would most likely have been confined to one area, most likely a body of water. But if this one area were a city, it wouldn't be quite so insignificant any more.
Regardless of the size of the asteroid, the fact is that it was only discovered on October 11th, 2007, and made its close approach on January 29th, 2008. Thats only a "preparation time" of about 15 weeks! Certainly enough time to evacuate a city (if you knew where it would impact), but nowhere near long enough to prevent an impact. So how much time would we need? According to Tom Gehrels in The Scientific American Book of Astronomy,
"If we have only 5 years' notice, we can say good-bye to one another... If we have 10 years or so, our chances are still slim..."This rather grim view of the situation may or may not be accurate, but the fact remains that the required "preparation time" is far longer than 15 weeks.
So we must start searching more fervently, and attempt to catalog a larger percentage of the "big" near-Earth objects. Asteroid 2007 TU24 wasn't "big" by any means, but there are plenty of big ones out there. Currently, near-Earth object, or NEO, hunters are detecting a staggering amount of NEO's. In the above chart, you can see the total number of NEO's discovered by each of the major five sky surveys. As you can see, the Catalina Sky Survey is currently leading in NEO discovery, and Catalina was the program that discovered 2007 TU24.
In addition to improved and continued funding of prediction of asteroids, we also need more funding of protection from asteroids. Space-based defenses will be our front-line defense from large asteroids, if world governments start funding such things. There are all kinds of ideas floating around, but not so many solutions. Ideas can't stop asteroids. For once in a species' lifespan, we have to ability to avoid our own extinction, to avoid the fate of the dinosaurs. Shouldn't Asteroid 2007 TU24 have been the wake-up call?
UPDATE: Upon further investigation, I've found this page, which details NASA's NEO Program's efforts to nail down orbital data on Apophis, a very large asteroid to make a really close approach in 2029 and 2036. Below, you can see that they actually have a plan laid out to get the orbital data figured in time for a possible intercept. This is the kind of planning I can appreciate.
Images courtesy of NASA/JPL-Caltech, Arecibo/Greenbank/NASA/JPL-Caltech, and NASA/JPL NEO Program, respectively.