There's a problem with this idea -- as you decelerate out of orbit, in order to reduce the craft's velocity so the inflated-bag method will work, the craft's angle with respect to the surface naturally changes and becomes nearly vertical. This is unavoidable.<p>Remember the early Mars missions that used the inflated-bag method? They had to expend a lot of fuel to slow down enough to safely approach the surface, at which point the air-bag method was used (and worked). But this only reduced the amount of fuel required to get to the surface, it didn't significantly change that cost and burden.<p>Just do some numerical orbital simulations -- see what happens when you slowly reduce the velocity and altitude of a craft orbiting the moon so it is able to graze the surface. See what happens when you impact the surface at shallow angles. Hint: the craft's velocity is still extremely high and the air bags have to absorb too much energy -- they will self-destruct.<p>In a hypothetical approach to a perfectly smooth plains area (the moon has plenty of those), in which there are no altitude irregularities and the craft can approach at nearly orbital speed and impact the surface at a very shallow angle, the craft would begin to roll along the surface at such a high velocity that the centripetal forces would tear the craft apart.<p>Speaking as a former NASA Space Shuttle engineer.