I was thinking of Shoemaker Levy 9 
which was once a single comet until it passed Jupiter and ended up looking like this. 
Which is probably exactly what they were thinking about when they decided to do the same thing in 'Armageddon.'
Edit: Come to think of it, I think the 'roid split up in 'Deep Impact' as well. But that might've been a direct result of an attempt to destroy it. Can't remember now. It's been too long.
Yes, it was. It was a comet though, 'Wolf-Biederman'. Part of the drama of the movie... lost a guy to an outgassing when the comet rotated out of 'night', and another guy got blinded by the sun due to not having his sheild down. They planted a nuke, blew it, and it made a chunk called 'Biederman'. That chunk, amazingly, was accelerated towards the earth, and was the size of Manhattan or something, and would impact the Earth several hours before 'Wolf' (the much bigger comet fragment left over) It would not cause an ELE, but it was definitely not going to be pretty. Wolf, though was still gonna cause an ELE.
Later in the movie, the Messiah was flown into a hole in the comet, nearer to it's heart (unlike the earlier nuke, which was a semi-near surface planting, but we're talking ice, so.. it should have made a slushy, but ice is really really hard in space) and the crew sacrificed the ship and themselves with a convenient second nuke they had on board, blowing up Wolf into so much crushed ice, mere hours, if not minutes, before impact. the remaning ice particles (and likely metals, sure) would individually slam into the atmosphere, but burn up and not make it to the ground... mostly.
And by far, the better of the two disaster asteroid/meteor/comet movies that year. Armageddon is the roughnecks in space silly movie, and with a meteor/asteroid. Oh sure, similarly fantastical (at this time), and much more over the top. Interesting note: It is likely that had not there been 'scout' meteors in both New York (lots of little ones) and Paris (a fairly big one) the monter one would not have been detected until it was amazingly late in the game. Please note that this is the likeliest scenario, no forewarning, much like the Russian meteor, we're not gonna know it's here until it's HERE
At least with a comet, you can see it coming a ways out, it can't help itself. Overall, Deep Impact was just so much more realistic in many ways, even if a bunch of hooey overall.
I liked it better because it was 'more correct', in a sort of fashion.
/Seriously? You're gonna put a nuke in the middle of the thing THAT CLOSE to earth and expect the halves to fly by?
//Riiight... And that's not the only thing, but it's enough.
///Entertaining enough though, I still enjoyed it, just recognize it's hokey silly.
