The other amazing thing about all this is that it's pure experimentation. There's no risk, aside from costs, if something goes wrong with this experiment. [...]
Well, not entirely. First: they add extra fuel for the braking burn (or reduce amount of fuel available for ascent). Second: the legs will change the aerodynamic, and maybe other characteristics of the fuselage.
They did a braking burn before, so I assume 1. is already tested, but I wouldn't say that there is no risk.
And that's why it's so exiting!
3-football-field-long asteroid as it zips by us at nearly 50x the speed of commercial airliner
and you are doing sunday-newspaper pop-sci, or use actual units:
1000 feet long asteroid as it zips by us at nearly 27000 miles/h
and qualify for pop-sci column in illustrated weekly. Don't mix the conventions!