Well, it looks like Mars isn’t going to get smacked at the end of this month after all. Astronomers are now giving the asteroid 2007 WD5 a 0.0 percent chance of hitting the planet, based on updated orbital information for the wandering bit of solar system debris. The best guess puts the asteroid on a close fly-by, passing about 7 Mars radii from the surface.Being the bloodthirsty lot we are, some of us at the AAS meeting last week were talking about how “cool” it would be if something DID smack into the surface of Mars, especially while we could watch it with orbiting spacecraft around Mars and the surface-bound rovers. I guess it’s the planetary science equivalent of being a pyromaniac (and watching things blow up).

Planetary Bod Mods

Impacts, which we don’t get to see happen very often, are one of the ways that solar system bodies are modified. Worlds can get smacked into, surfaces can be eroded by weather and other atmospheric processes (like rain and snow (and not just rain and snow made of water, mind you)), they can be paved over by volcanism, or they can be disturbed from below the surface (quakes and subsurface activity driven by internal heat).

Mars has been modified by all these processes over the billions of years it has existed. Take a good look at any picture of Mars, like the one below (taken by the Mars Global Surveyor on August 8, 2006), and you’ll see impact craters, or canyons, or the remains of what look like dry riverbeds tracing their way across the plains.

Every one of those surface features has a story to tell about some aspect of Mars history, and we’re just now decoding what they have to say. So, while I’d have loved to have seen the effect of an asteroid smackdown on Mars, I’m not too upset that it’s missing the planet. There’s plenty of “cool” stuff to study already!