<blockquote><font class="small">In reply to:</font><hr /><p>But looking at the photo, there is one thing that still doesn't jive for me. There is no crater under the LEM. The engine was running up until touchdown right ? So why no dust has been displaced ? <p><hr /></p></p></blockquote><br /><br />Basically, it *was* displaced -- just not the way you're expecting.<br /><br />The top layer of dust is very light, but get down a little ways and it's packed so hard it's practically solid. The astronauts actually had a tough time planting the flag because of that. With the engine throttled waaaaay back for landing, it easily blew the loose dust away from the surface, but didn't really make much of an impression on the hard-packed stuff beneath. You can actually see the dust being blown away in a radial pattern if you watch the footage of the landings.<br /><br />So the answer is twofold -- the engine was not on full blast at touchdown, but throttled back gently during the course of the final descent to cushion their touchdown, and no crater is visible because while it was easy to blow away the dust, digging into the packed regolith would've taken a lot more power. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em> -- The Tenth Doctor, "Blink"</font></p> </div>