I suggest you make it possible to put all parameters as URL extensions, with a "Copy impact link" (or "share impact on Twitter") button once the asteroid is launched. This would allow visitors to copy and share impacts to their (least) favorite places.

Also those speed and impact angles values are a bit dry - why choose one over the other? Make the ranges more relevant e.g. typical interstellar visitor, Oort asteroid etc. Or simply propose ready-made impactors, such as Chicxulub dinosaur killer, Halley comet, Tunguska event, rocks from "The Moon is a harsh mistress" etc.

>18 feet across and weighs 14,360 pounds

For true Americans who reject colonial British units, that's 0.06 football fields and 30,952 Big Macs. For the rest of us, that's 5.5 meters and 6.5 metric tons.