Well, the NASA machine weighs about a ton, and would need a great deal more to slow it down; the atmospheric pressure on Mars is only about one percent (or is it less? I forget!) than Earth's, so the parachute alone wouldn't be enough. Extra airbags and rockets would have easily quadrupled B2's mass, along with all the knock-on problems: more fuel (and more mass) for the launch vehicle, less space for all the other Mars Express payloads ...

But full marks to NASA: everyone here is very happy for their success. It's not a competition -- except for governments and big businesses.

Steve