Glenn at Instapundit points to a UPI story that says JPL thinks the odds of a 4,000 km flyby for 2007 W(M)D5 or less is 99.7%. If it's not going to hit Mars, that increases the chances that it will slingshot around Mars toward Earth. Odds are likely in the 1 in a million range or less, but what if it did? I wouldn't say "probably", but let's have some transplanetary musings!

No one is making any calculations to see how close to Phobos or Deimos it is coming?

That would be incredibly interesting and would probably make a manned Mars mission an improbable occurance for decades.

Dennis seems they've been looking into it. From Wikipedia:
"December 28, 2007: NASA scientists at the Near-Earth Object program office at JPL announced they had found 2007 WD5 in 3 precovery images from November 8, 2007. The refined orbit placed the odds of a Mars impact at 1-in-25. The uncertainty region was reduced from 1 million km to roughly 400,000 km.[2] The best fit trajectory had the asteroid passing within 21,000 km of Mars and only 16,000 km from the moon Deimos.[7]"

Also further down (part of the latest information):
"The best estimate is that the asteroid will pass about 26,000 km (0.00017AU)[10] from the planet's center (about 7 Mars radii from the surface)."
So I guess that makes it unlikely to break apart due to Mars' gravitational influence which could have been an interesting and educational experience as well.

Habitat Hermit:

Tidal breakup was unlikely for this object anyway. It's too small. If it's rock (or even solid ice) rather than a rubble pile, it's too strong as well, for tides to break it over a diameter of 200 metres or so.

Fletcher,

Actually, that raises an interesting point.

If it *is* a rubble pile, does that mean it could be tidally disrupted? I would think that would be an interesting observation...

How close to the surface of Mars would a fly-by need to be in order to shift the trajectory enough to make its orbit cross Earth's?

Assuming it's coming this way, how about a poll on where on Earth we'd like it to hit? ;-)

It misses Mars .. and we loose an opportunity to see what global catastrophe looks like.

Of course seeing that won't really change the public's mind about needing a species insurance policy against extinction ... but it might sway some people.

Odds are likely in the 1 in a million range or less, but what if it did?

Stock the basement and review business continuity plans at work.

...and we loose an opportunity...

Aaaarrrgghhhh...

Aaaarrrgghhhh...

Type in haste, repent at leisure. Sorry 'bout that.

2007 WD5 does make a couple of "close" approaches in 2084 (.111 AU )and 2088 (.094 AU). It will be interesting to see if these are effected. But I would be surprised if this close approach makes it a hazard to Earth.

Speaking of annoying word errors:

Effect (n) result, outcome

Affect (v) To influence, to change

"The medication being tested shows no adverse effects"

"The patient was not adversely affected by the procedure."

I'm not throwing stones here, my house is solid glass as well.

I guess I'm guilty of a fly-by night operation. Maybe the flyby should be closer.

Sam,
Its been a while since I took Orbital Mechanics but I think that if the Earth were several months behind its current position relative to Mars, rather than at opposition, then the odds of such an impact might be on the order of several tens of billions to one. With Mars and Earth at opposition, its virtually impossible. One in a million is vastly too likely.

Michael,

I think you're misreading Sam's question. He's not proposing an *immediate* Earth encounter post-Mars, but wondering if Mars will affect the object's orbit enough and in the right direction to increase the chances of an Earth encounter *in the future*.

Tom's references seem to indicate that the object is already an Earth-orbit crosser, or nearly so, so it's entirely possible that the Mars encounter could increase the probability of en Earth encounter.

Glenn,

Or it could equally reduce the chances. In any case it will be critical to track it after this close encounter so it doesn't become lost as a result.

lmg:

Pointless shoo-in. A certain lump of black rock in the Middle East has to be the favourite.

A certain lump of black rock in the Middle East

Given notions like this, I wonder if we could increase the odds by dubbing the asteroid "Iblis?"

McGehee, interesting idea. However, it might reinforce the idea in certain quarters that Western culture is inspired by Satan.

To remind those certain people of some of the less tolerant aspects of the heritage of the UK and USA both, and that those aspects might come back, I propose the name Mjolnir. Of course, the message would likely not be understood...