How can the Mars asteroid hit "near the Opportunity rover"?

Question

I read in a news story that if this Mars-bound asteroid collides with the planet " it will do so near the location of its Opportunity rover, which has been exploring the Martian surface for three years."

I also read the chance it will hit the planet is 1/75. Here I see a contradiction -- if you can't predict it will even hit the planet, how can one say it will hit near the rover?

I'm guessing that all that can be predicted is that if an impact occurs it will be somewhere on the same side of the planet that Opportunity is on. I'd hardly call that "near."

Any other ideas?

EDIT--

Now I see how the possible impact zone can be long and narrow so it only covers a portion of the planet. I had assumed the cross section was circular.

How is it that one dimension can be more accurately know than the other?

Answer 1

The most recent information from JPL indicates that the potential window through which the asteroid will pass is a wide but shallow window which extends well on either side of the planet, but passes close to Opportunity's location on the planet. See the maps in the source below.

Answer 2

When an observatory says that there is a 1/75 chance that an asteroid hits the planet they are not sure that the impact will occur, like in this case. There are some uncertainties in the movement of the asteroid that don´t allow a precise prediction. This uncertainties will be reduced as more and more observations are made.

Answer 3

(EDIT) Oh, Geoff G got it. I'll go with that answer.

Here is what space.com says:

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.

So I guess there is an area that the asteroid can pass through, and 1/75 of that area intersects the planet, and the part of the planet where it intersects is near one rover.

Answer 4

if there is a 1/75 chance that the asteroid will hit mars then obviously there isnt a chance that it will land anywhere on the planet. picture 2 things, mars as a sphere, and the orbit of the comet as a large cylinder. since theres only a small chance they will hit imagine the 2 intersecting just barely. that area is where opportunity is.

Answer 5

it says that rover is far enough away from the impact zone. but i think that the dust coming off the impact might affect its solar shields.

Answer 6

one dimension can be more accurately calculated than another because range and range rate estimates are much harder to calculate than bearing estimates (as seen by a terrestrial observer), and since the moving object is not bore sighted to us (thankfully) its path estimates are not going to be circularly conical.

Answer 7

It does seem ridiculous for me too..
But this kind of subject interests me a lot so I will keep my eye on it.

Answer 8

look at jpl