If the asteroid does smash into Mars, it will probably hit near the equator close to where the rover Opportunity has been exploring the Martian plains since 2004. The robot is not in danger because it lies outside the impact zone.
If they can't even say it will hit (75 to one?) how can they possibly say the rover is outside the impact zone if it does? I mean, the odds are good that it is, since the 'zone' is currently larger than the entire planet, but come on.
Good point. I'd love someone to explain this.
You're thinking only of the spacial dimension. Think time as well. They know the plane of the orbit pretty well I would imagine, but can't quite tell if Mars will be there when the object crosses Mars' orbit. But if it is, I imagine they can tell where the uncertainly in the orbit would cut across Mars, in latitude anyway.
Just guessing, but here’s how I’d decipher that comment:
You’ve heard of confidence intervals in elementary statistics? Well, when we’re dealing with two or more dimensions, we speak of confidence ellipses or ellipsoids, not intervals.
So, with the data now available they are able to calculate a confidence ellipse, or window, through which the asteroid is likely to pass when it flies by Mars. About 1/75th of that ellipse intersects Mars’ surface and thus, with the data now available at least, it looks like there is a one in 75 chance of it impacting the surface.
But like I said, that’s a totally stat-centric guess. I’m not an astronomer and could be way off base!
Perhaps if there is any collision at all, it means that the asteroid has come under the influence of Mar’s gravity. That being the case, it will be attracted toward the center of the planet. In other words, glancing blows not possible? Bull’s eye or nothing?
Or do they know what side the rover is on and know that the other side will be facing the asteroid at moment of impact?
After all, we can be pretty sure which way the earth will be facing at midnight, local time, a hundred years out- i.e. away from the sun.
I know that for earth threatening objects, the probability of impact is calculated taking a draw from a population representing the supposed distribution of the orbital elements, propagating it and seeing whether or not it impacts the earth. This process is repeated literally millions and millions of times and the probability of impact is the relative frequency of hits.
If they applied similar techniques to this asteroid, they may have seen that the draws that result in an impact (and there would be a lot of them) are clustered around a certain area of Mars, let’s call it “the impact zone”. If none of them were anywhere near Rover, then they might, not altogether unreasonably, conclude that “Rover is outside the impact zone.”
What he said. Mars rotates on its axis, so (depending on the amount of ejecta and how far it gets flung of course) apparently the impact (should it occur) will be on the other side compared to the rover location. :’)
Thanks dayglored, El Gato, willyd, lentulusgracchus, Lonesome in Massachussets, and Rightwhale.
http://www.freerepublic.com/focus/f-news/1942591/posts?page=21#21
Oh, and to those who think so, NO, the atmosphere doesn’t protect the surface from all impacts. Stuff large enough to wipe out, say, Chicago, would zoom right through, burning its path through, perhaps in under one second.