[diggernet]

I suppose that a last-instant firing is a plausible explanation, and would greatly reduce physical damage to the capsule. But then the talk of a "gentle" 3mph touchdown is conveniently ignoring the 16->13 deceleration a split second before. As you say, it's likely preferable to 15->0, but I suspect not a whole lot more pleasant to experience. The astronauts would probably not even notice the actual touchdown an instant later.

[phire]

The goal is to stretch out the deceleration. Instead of going from 16 to 0 instantly (probably more like 1/10th of a second when you count the capsule deforming), it's going from 16 to 0 over a much larger fraction of a second.

It's probably the difference between running full speed into a brick wall and running full speed into a large foam pad.

The foam pad decelerates you in less than a second, but it's a whole lot more comfortable than the brick wall.