They made some assumptions out of necessity, but some of them are questionable. Since one of the shuttles lands on a field of "iron ferrite", they assume the entire asteroid is iron, with a density 7000 kg/m^3. However, it is implied in the movie that landing at that spot was particularly bad luck since there were other landing spots that weren't iron plates. The actual bulk density of most asteroids is between 1000 and 3000 kg/m^3. http://www.lpi.usra.edu/books/AsteroidsIII/pdf/3022.pdf Furthermore, "the size of Texas" was assumed to mean a sphere 1000km across. Saying a sphere is the same size as a two-dimensional object is meaningless, so it's tough to say how big the asteroid was meant to be. If we were trying to make the plotline work, we might say that the asteroid had the same surface area as Texas. That means a sphere with diameter ~300km, or a misshapen object (like most asteroids are) of significantly less mass than a 300km sphere. Not to diminish the value of this project for teaching physics, but in about 15 minutes of Googling I reduced their "9 orders of magnitude" claim to 7 orders of magnitude, even less if you take the low estimates on both density and diameter. Next step in making the plotline work (but it would require actual thought, so I'll leave it as an exercise for the reader) is to see if the movie indicates the asteroid is headed right at the center of Earth. If not, perhaps it would be necessary to split the asteroid into two equal hemispheres, but instead to push most of the asteroid off in the short direction, and a smaller piece of asteroid at a higher velocity in the opposite direction. Not sure how much that reduces the required kinetic energy (if at all), though.

I know the article claims "Calibration--a standard procedure used by all modelers in all fields, including finance--had rendered a perfect model seriously flawed." but obviously our climate models are simple enough that you can't just calibrate the parameters until it matches the data, right?

Correct me if I'm wrong, but I thought salting still helps in this case. If I use a 6-character password and the hash falls into the hands of the attacker, the attacker will be able to find a collision in at most 256^6 attempts. But if my password is salted first (and the attacker doesn't know the salt), the search space increases dramatically, does it not? Or is it assumed that if they have the hash they have the salt, too?

The centrifugal force would indeed keep the cable quite taut. So taut, in fact, that any known material (of sufficient length) would snap. The closest we can get to a strong enough material is currently produced in lengths of centimeters or so, and the longer you make it, the higher the probability that there's a fatal defect in it.