I think the speed of the object plays a factor. Christopher mentioned a shuttle traveling at "relativistic speed" could do that much damage.
Yes, that's right. Kinetic energy equals mass times velocity squared. So something traveling at, say, a thousand times the velocity of the Chicxulub asteroid would only need one millionth of the mass to do an equal amount of damage.
According to Edward Muller's Antimatter Calculator (http://www.edwardmuller.com/right17.htm
) the Chixulub asteroid energy was around 100,000,000 Megatons. According to this(http://www.1728.org/energy.htm
) a 12,500 pound object(the size of a twin otter air craft) traveling at 250,000 Kilometers a second would hit with a force equal to 42,348 Megatons.
so while I don't think a shuttle could do that kind of damage (then again we don't know how much a shuttle weights I plugged in weight of a large light aircraft) and while the energy is clearly less it worth remembering that the shuttle would hit with a force equal to 1000 times the large nuclear bomb ever tested.
Put another way a gram object would hit with a force equal to 7 kilotons or it would take a 2 gram object to hit with the force of the hiroshima bomb
Just to put it perspective