It’s Not the Impact You Think It Is

You may have heard (or seen in the news) about an asteroid that’s due to pass close to Earth on January 29 (next Tuesday). It’s called 2007 TU24, it’s about the size of the Sears Tower in Chicago, and it will flash past at a distance of about 537,000 kilometers. To put it in perspective, the Moon lies 383,180 kilometers away, so this thing isn’t getting as close to us as the Moon is.

This is a rare chance for astronomers to image a near-Earth asteroid and use instruments such as the Arecibo radio telescope to accurately measure its size, spin rate, and orbital speed.

Stuff like this passes near our planet rather frequently; after all, space is full of debris left over from the formation of the solar system, and not all of it has been swept up by planets, moons, and ring systems. That’s the beauty of having an evolving planetary system. Now that we have good instrumentation, we can study these pieces of debris and learn a variety of things: what they’re made of; and from their orbital measurements, we can figure out the larger picture of orbital dynamics. And, of course, we can learn more about how to spot these things and determine if (and very, very rarely when) they might pose a threat to the planet.

Now, there are a few whack jobs out there who are using this upcoming event to draw attention to themselves by making outrageous claims. It’s the usual huffing and puffing and uninformed bloviating about how NASA is hiding evidence that the rock is actually going to HIT Earth, yadda, yadda, yadda. And I have to wonder just how much physics these folks ever studied, or passed? And what part of “it’s farther away from us than the Moon is” didn’t they get?

I’ve calculated a few orbits in my time (and by the way, doing a general orbit calculation isn’t rocket science—kids in high-school math and physics probably cut their teeth on these things in middle school these days) and I’m here to tell you it’s not difficult. And what you learn tells you pretty quickly just how much chance there is an impact vs. a flyby.

Here’s how it works. You observe an object and plot its position. Then you do it again. And again. Pretty soon you have a line that, after you’ve got enough positions, allows you to plot the entire orbit pretty quickly. Once you do that, you can see where the object is going to be as it moves along in its orbit.

You can understand roughly how this works by watching cars on a road. After a while, assuming that the cars are going the same direction, not turning off on other roads, and they’re not whacking into each other, you will be able to “predict” that a car going a given speed down the road will be at Point B at a certain time, then Point C, and so on.

Now, the people at JPL whose job it is to calculate orbits have done a very refined job of plotting the orbit of 2007 TU24. And guess what? It’s not going to hit us. Physics and orbital mechanics tell us this.

There’s no hidden agenda. NASA isn’t hiding anything. It’s all in the physics and orbital mechanics. Even if NASA tried to suppress knowledge, the amateur astronomy community can often see these things and those folks can calculate orbits, too. It takes no esoteric knowledge, just the ability to apply the laws of orbital motion. And actually, if you can get hold of orbital elements (and they ARE freely available) YOU can plot an orbit. And you’ll see that the thing is going to miss Earth by a long shot.

So, let’s apply a little common sense here and use some science to understand these things. If somebody wants to believe hyperbole and self-serving claims of cover-ups and other malarkey, let’s be clear that it’s really about delusions of grandeur among those who are too lazy to do the math. And that’s fine (although silly). People can think or believe what they wish. But, wishing doesn’t make it so.

Uninformed ravings about coverups and plots and so on simply prove that the only impact we’ll see on Tuesday is that of lazy thinking. Perhaps we can use that kind of impact as a lever for more effective science education in our schools and less foolishness.

For more information on this event and the orbital calculations, check out the Near-Earth Object Program page at NASA.